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CAMDEN POWER STATION 6,6kV SWITCHGEAR 6,6kV SWITCHGEAR REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Title: Camden AHP Medium Voltage Switchgear Requirements Document Identifier: Camden Power Station 383-CAHP-AAAC-D00132-1 HBS / Functional Location): *BCA, *BCG Area of Applicability: Electrical Plant Functional Area: Operating, Common plant, Electrical reticulation Revision: 0 Total Pages: 47 Next Review Date: TBA Disclosure Classification: Controlled disclosure Compiled by Supported by Functional Responsibility Authorized by J. A. Moolman MP Ngubo P Rakeketsi T Railo Snr Consultant Elec Lead Engineer EPI - Discipline Elec CoE Power Stations GTE- Electrical Design Application CoE Manager Manager GTE- Electrical Design Application CoE GTE- Electrical Design Application CoE Date: Date: Date: Date: REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 1 CAMDEN POWER STATION 6,6kV SWITCHGEAR CAMDEN POWER STATION 6,6kV SWITCHGEAR REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Index Table of Contents 1 General .............................................................................................................. 5 1.1 SCOPE 5 1.2 EQUIPMENT TO BE SUPPLIED AND INSTALLED 5 1.3 APPLICABILITY 6 REFERENCES 6 1.4 2 3 4 Normal and Special Service Conditions .......................................................... 6 Definitions and Abbreviations .......................................................................... 6 Ratings and Operating Conditions .................................................................. 7 4.1 PANEL RATINGS 7 4.2 RATINGS - SWITCHING DEVICES 7 4.3 RATED VOLTAGE 7 4.3.1 4.3.2 4.3.3 4.3.4 System normal power supply conditions ................................................ 7 Circuit Breaker Auxiliary Coils ................................................................ 8 Harmonic Voltage Distortion .................................................................. 8 System abnormal power supply conditions ............................................ 8 4.4 RATED INSULATION LEVEL 9 4.5 RATED FREQUENCY LEVEL 9 4.6 RATED NORMAL CURRENT AND TEMPERATURE RISE 9 4.7 RATED SHORT-TIME WITHSTAND CURRENT 10 4.8 RATED PEAK WITHSTAND CURRENT 10 4.9 RATED DURATION OF SHORT CIRCUIT 10 4.10 RATED SUPPLY VOLTAGE OF CLOSING AND OPENING DEVICES AND OF AUXILIARY AND CONTROL CIRCUITS 10 4.11 RATED SUPPLY FREQUENCY OF CLOSING AND OPENING DEVICES AND OF AUXILIARY CIRCUIT 10 5 Design and Construction ................................................................................ 10 5.1 SWITCHGEAR AND CONTROLGEAR 5.1.1 5.1.2 11 General ................................................................................................ 11 Operating Service Requirements ......................................................... 11 REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 2 CAMDEN POWER STATION 6,6kV SWITCHGEAR 5.1.3 5.1.4 5.1.5 5.1.6 5.1.7 5.2 Internal Arc Classification .................................................................... 12 Segregation of Compartments ............................................................. 13 Power Cable Entry and termination ..................................................... 19 Earthing ............................................................................................... 21 SPECIAL CONSIDERATION FOR INTERNAL ARC PROOF DESIGN 21 PROTECTION 5.2.1 5.3 22 General ................................................................................................ 22 INTELLIGENT ELECTRONIC DEVICES 5.3.1 5.3.2 5.3.3 5.3.4 5.3.5 5.3.6 5.3.7 5.4 ARC DETECTION SYSTEM 5.4.1 5.4.2 5.4.3 5.4.4 5.5 PROTECTION SCHEMES ARC PROTECTION SCHEME CIRCUIT BREAKERS 33 General ................................................................................................ 33 Inter-changeability ............................................................................... 33 Circuit-breaker truck connections ........................................................ 33 Shutters ............................................................................................... 34 Mechanisms ........................................................................................ 34 Tripping Devices .................................................................................. 35 Indicating Devices................................................................................ 35 Auxiliary Contacts ................................................................................ 35 Control Connector................................................................................ 36 Insulation Level .................................................................................... 36 EARTHING DEVICES 5.8.1 5.8.2 30 General ................................................................................................ 30 Current Detection Methods .................................................................. 30 Circuit Breaker Failure Protection ........................................................ 31 Busbar Chamber Protection................................................................. 31 Protection of Circuit Breaker Compartment ......................................... 31 Protection of Cable Termination Compartments .................................. 31 Buszone Protection Scheme ................................................................ 32 DC Fail Function .................................................................................. 32 5.7.1 5.7.2 5.7.3 5.7.4 5.7.5 5.7.6 5.7.7 5.7.8 5.7.9 5.7.10 5.8 27 Motor Protection Scheme (Motors ≥ 1 MW) ......................................... 27 MV Interconnector Protection Scheme ................................................ 28 Transformer Feeder Protection Scheme (Transformer < 10 MVA) ...... 29 MV Incomer Protection ........................................................................ 29 5.6.1 5.6.2 5.6.3 5.6.4 5.6.5 5.6.6 5.6.7 5.6.8 5.7 26 Protection Relays................................................................................. 26 Light Sensors....................................................................................... 26 Monitoring ............................................................................................ 26 Auxiliary Relays ................................................................................... 26 5.5.1 5.5.2 5.5.3 5.5.4 5.6 22 Design and Construction...................................................................... 22 Functions ............................................................................................. 23 Software .............................................................................................. 24 Analogue Voltage and Current Inputs .................................................. 24 Output Contacts ................................................................................... 24 Testing of Devices ............................................................................... 25 Buszone Protection Relay .................................................................... 25 36 General ................................................................................................ 36 Busbar Earthing Devices ..................................................................... 37 REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 3 CAMDEN POWER STATION 6,6kV SWITCHGEAR 5.8.3 5.9 Cable Earthing Device ......................................................................... 37 ACCESSORIES 5.9.1 5.9.2 5.9.3 5.9.4 5.9.5 5.10 38 Current Transformers .......................................................................... 38 Voltage Transformer ............................................................................ 38 Indicating and Measurement Instruments ............................................ 39 Selector Switches ................................................................................ 39 Cable Live Indicators ........................................................................... 40 TERMINALS 5.10.1 5.10.2 5.10.3 5.10.4 40 Material and Construction .................................................................... 40 Mounting .............................................................................................. 40 Types ................................................................................................... 40 Wiring and Cable Lugs ........................................................................ 40 5.11 LABELS 41 5.12 NAMEPLATES 41 5.13 SWITCHGEAR INTERLOCKING SYSTEMS 42 TESTING AND DOCUMENTATION OF TEST REPORTS 43 5.14 5.14.1 Type Test ............................................................................................ 43 5.14.2 3.9.2 Routine Tests.............................................................................. 43 5.14.3 Special Tests ....................................................................................... 43 5.15 MAINTENANCE AND OPERATION 44 5.15.1 Maintenance and Operating Tools ....................................................... 44 5.15.2 Maintenance and Operating Instructions.............................................. 45 5.16 DOCUMENTATION 45 5.16.1 Language ............................................................................................ 45 5.16.2 Type Test Reports ............................................................................... 45 5.17 MANUALS AND DRAWINGS 45 5.18 PACKAGING, TRANSPORTATION AND HANDLING 46 REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 4 CAMDEN POWER STATION 6,6kV SWITCHGEAR 1 GENERAL 1.1 Scope a. This requirements specification provides for the manufacture, testing before despatch, supply, delivery to site, off-loading, erection, site testing and commissioning and handover after commissioning to the power station. b. Each panel is completed with all the necessary connections, interconnecting wiring, fuses, supporting steelwork, hold down bolts, guards, labels and accessories to make a complete functional assemble in the case of a complete switchboard and in the case of additional panels to be connected to existing 6,6kV boards as per this this specifications. c. The specifications define the requirements for: - Specific design and specifications of the switchgear, - Safety of personnel and equipment with regards to the use of this switchgear, - Specific design and technical, operation of the switchgear, - Maintenance and return to service of the switchgear. d. If the Contractor cannot supply the equipment offered in Schedule B at the time of delivery the next bigger size of equipment that is available is supplied at no extra cost to the Employer. e. The switchgear is of the withdrawable type, internal arc classified (IAC) of the modular design with air-insulated busbars for the use on 3-phase systems rated at 50Hz. f. 1.2 Components used in the switchgear are designed, manufactured, installed and tested in accordance with the manufacturer’s specifications and requirements with these specifications supplementary. Equipment to be supplied and installed a. 6,6kV Ash Water Return Plant Boards 1 & 2 - Install two (2) 6,6kV Boards consisting out of six (6) panels each, to be installed inside the Ash Water Return Pumphouse near the Ash Water Return Dam. Each board are equipped with busbar compartment, circuit breaker compartment and cable compartment internal arc protection. The protection is in compliance with Eskom Standard 240-56357424, MV and LV Switchgear Protection Standard. b. 6,6kV Station Boards 3 & 4 - Install one 6,6kV, 630A, complete panel, equipped with a 6,6kV, 630A circuit breaker on 6,6kV Station Board 3. The panel shall be equipped with busbar compartment, circuit breaker compartment and cable compartment internal arc protection. The protection is in compliance with Eskom Standard 24056357424, MV and LV Switchgear Protection Standard. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 5 CAMDEN POWER STATION 6,6kV SWITCHGEAR - Install one 6,6kV, 630A, complete panel, equipped with a 6,6kV, 630A circuit breaker on 6,6kV Station Board 4. The panel shall be equipped with busbar compartment, circuit breaker compartment and cable compartment internal arc protection. The protection is in compliance with Eskom Standard 24056357424, MV and LV Switchgear Protection Standard. c. 6,6kV Sub-Station Boards 1, 2, 3 & 4 – ABB Uniflex Type - Replace all eight Ash Pump Motor 6,6kV VC’s on 6,6kV Sub-Station Boards 1, 2, 3 & 4 with 630A, SF6 VCB’s including the protection relays (Eskom Standard 240-56357424, MV and LV Switchgear Protection Standard) and internal arc protection as for circuit breaker panels. The 6,6kV panels of the ash pumps will remain in its current position. - Replace all eight Sluice Pump Motor 6,6kV VC’s on 6,6kV Sub-Station Boards 1, 2, 3 & 4 with 630A, SF6 VCB’s including the protection relays (Eskom Standard 240-56357424, MV and LV Switchgear Protection Standard) and internal arc protection as for circuit breaker panels. The 6,6kV panels of the ash pumps will remain in its current position. d. 6,6kV Sub-Station Boards 1, 2, 3 & 4 – ABB Uniflex Type - 1.3 Install one x 630A, 6,6kV panel on each of 6,6kV substation boards 1, 2, 3 & 4 to supply the 6,6/0.4kV Aeration Transformers 1, 2, 3 & 4 to be installed on Units 1 to 8 ash hoppers. Applicability This specification is applicable to the 6,6kV switchgear and controlgear at Camden Power Station. 1.4 References References are discussed under the Works Information, Section 2 of this enquiry document. 2 NORMAL AND SPECIAL SERVICE CONDITIONS The switchgear is to be used as per the Schedule A of these specifications. 3 DEFINITIONS AND ABBREVIATIONS IEC – International Electrical Commission SANS – South African National Standards NPS – Negative Phase Sequence PPS – Positive Phase Sequence ZPS – Zero Phase Sequence THD – Total Harmonic Distortion REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 6 CAMDEN POWER STATION 6,6kV SWITCHGEAR 4 RATINGS AND OPERATING CONDITIONS 4.1 Panel Ratings a. The switchgear and control gear ratings and operating conditions, its auxiliary equipment is in accordance with SANS 62271-200, the stipulations of Eskom requirements and standards as provided in Schedule A. b. Thermal ratings are as per these stipulations of this document and its attachments. Panels are fully type and routine tested at the specified ratings. c. The motor starting currents and number of starts per hour as specified are taken into account when the temperature rise limits are verified or tested. 4.2 Ratings - Switching Devices a. The circuit breakers are rated for the continuously carrying the circuit breaker current rating as specified in Schedules A & B at the specified altitude for an ambient temperature of 40°C. b. The circuit breakers are rated for all the current ratings of the circuit breaker in the service position within the fully assembled and functional unit. c. The circuit-breakers shall be capable of interrupting, making, latching against and able to withstand the specified fault duties at the maximum specified voltage. d. The circuit-breaker shall be classified as Class E2 in accordance with SANS 62271-100 without reclosing. Auto-reclosing is not required. e. The circuit-breaker shall be classified as Class M2 in accordance with SANS 62271-100. f. Earthing devices shall be classified as Class E2 in accordance with SANS 62271-102, as a minimum. g. Earthing devices shall be capable of enduring a minimum of 2000 mechanical operations. h. The short-circuit withstand current rating and insulation level of an earthing device shall match that of the panel. The duration for the test will be 3 seconds. i. 4.3 The connection between the earthing device and the panel earth bar shall be designed to withstand the panel short-circuit withstand rating for same duration. Rated Voltage The rated voltage is in accordance with SANS 62271-200, this specification and the values as per Schedule A. 4.3.1 System normal power supply conditions The extremes of these parameters can occur simultaneously: Voltage ± 5% Voltage imbalance NNPS voltage up to 0.02 of nominal PPS voltage ZPS voltage component can 1% of the PPS REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 7 CAMDEN POWER STATION 6,6kV SWITCHGEAR be up to 4.3.2 Circuit Breaker Auxiliary Coils - Shunt-closing release – Between 85% and 110% - Shunt-opening release – Between 85% and 110% - Under-voltage release – below 35% of the rated voltage 4.3.3 Harmonic Voltage Distortion a. The harmonic distortion of the supply voltage under normal operation is as follows: - The Total Harmonic Distortion (THD) of the voltage can be up to 5% of the fundamental component. - The voltage waveform can contain harmonic components up to the 100th harmonic. - The amplitude of any individual component can be up to 1% of the fundamental component. 4.3.4 System abnormal power supply conditions The following are typical operating characteristics which can occur on auxiliary supplies. 4.3.4.1 Power supply abnormal operating characteristics a. The supply voltage frequency can reach limits of up to 52,5 Hz and fall as low as 47,5 Hz. This condition can last for up to six hours. b. The amplitude and duration of temporary abnormal voltage operating characteristics which can occur on the power supply are as follows: 4.3.4.2 Short duration abnormal conditions a. Short duration under voltage conditions arise either due to a loss of supply or the supply voltage being depressed due to a short circuit on the network. 4.3.4.3 Loss of power supply a. When the supply is disconnected, the supply voltage either drops rapidly to 0% of nominal value or is sustained at low amplitude at a reduced frequency because of back generation of electrical drives. b. The initial voltage amplitude during these conditions are less than 80% of the nominal value and decay with a time constant of up to 1,5 seconds. c. The time duration from loss of supply until supply restoration is between 1 second and 1,5 seconds. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 8 CAMDEN POWER STATION 6,6kV SWITCHGEAR 4.3.4.4 Short circuits a. Depression of supply voltage due to short circuits can result in voltages as low as 0% of nominal value. The duration of the drop can be up to 1 second. 4.3.4.5 - Overvoltage’s a. Over-voltages with a amplitude of 110% of nominal value can occur for up to 10 seconds. 4.3.4.6 Medium duration power supply deviations a. Voltage depressions of medium duration can be caused by the switching of load such as induction motors. b. The supply voltage can fall as low as 75% of nominal value and the duration of this depression can be up to 10 seconds. c. An alternative source of this abnormal condition is when power swings occur after a severe disturbance on the network. d. The supply voltage amplitude oscillates at a frequency between 0,2 and 2 Hz. e. In this case the voltage can fall as low as 65% of nominal and can rise up to 110% of nominal during a swing. f. The voltage does not fall below 70% for longer than 0,5 seconds. However, these oscillations, or repeated abnormal voltage conditions, can continue for up to 60 seconds. 4.3.4.7 Long duration power supply deviations a. Long duration abnormal supply voltage conditions usually originate from operating the plant at its limits. b. The supply voltage can be up to 110% of nominal value and can drop as low as 90% of normal value. The duration of such abnormal conditions is up to 6 hours. 4.4 Rated Insulation level The rated insulation level is in accordance with SANS 62271-200, this specification and the values as per Schedule A. 4.5 Rated Frequency level The rated frequency level is in accordance with IEC 62271-200, this specification and the values as per Schedule A. 4.6 Rated Normal Current and Temperature Rise The rated normal current and temperature rise is in accordance with SANS 62271-200, this specification and the values as per Schedule A. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 9 CAMDEN POWER STATION 6,6kV SWITCHGEAR 4.7 Rated Short-time Withstand Current The rated voltage is in accordance with SANS 62271-200, this specification and the values as per Schedule A. 4.8 Rated Peak Withstand Current The rated peak voltage withstand current is in accordance with SANS 62271200, this specification and the values as per Schedule A. 4.9 Rated Duration of Short Circuit The rated duration of short circuit is in accordance with SANS 62271-200, this specification and the values as per Schedule A. 4.10 Rated Supply Voltage of Closing and Opening Devices and of Auxiliary and Control Circuits The rated supply voltage of closing and opening devices and of auxiliary and control circuits are in accordance with SANS 62271-200, this specification and the values as per Schedule A. 4.11 Rated Supply Frequency of Closing and Opening Devices and of Auxiliary Circuit The rated supply frequency of closing and opening devices and of auxiliary circuit is in accordance with SANS 62271-200, this specification and the values as per Schedule A. 5 DESIGN AND CONSTRUCTION a. The new boards, replacement of VC’s with SF6 VCB’s and additional panels are of the indoor type, trunk type circuit breaker, being able to be removed from the breaker compartment by means of a trolley (Withdrawable) and internal arc classified AFLR for 1 second in accordance with the requirements of SANS 62271-200. b. The switchboards are of the modular design to allow for air insulation and the subsequent addition of identical panels. The design allows for human safety and as little as possible time to RTS in the case of an internal arc fault. c. The new switchgear and controlgear are of the behind-closed-door operation. d. Circuit breaker trolleys are supplied with the boards to allow for the removal of circuit breakers with regards to maintenance and isolation activities. e. The switchgear and controlgear are clearly marked as per this specification with the ratings to which the equipment has been type tested. Ratings shall be displayed as per SANS IEC 62271-1, section 5.10. f. CT labels are displayed in the LV compartment and inside the cable compartments. g. Oil filled circuit breakers, voltage transformers are not acceptable due to the risks and dangers attacked to oil filled medium voltage equipment. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 10 CAMDEN POWER STATION 6,6kV SWITCHGEAR 5.1 Switchgear and Controlgear 5.1.1 General a. The new 6,6kV Ash Water Return Plant Boards 1 & 2, the additional Uniflex 6,6kV panels are of the metal-enclosed type switchgear and control gear, of a proven design and fully type tested. The design of the switchgear and controlgear complies with the requirements of this specification and the following: - Schedule A – attached to Annexure 1. The contractor completes schedule B of the attachment to Annexure A. - Schedule C – attached to Annexure 2. Type-testing requirements. - Schedule D – Attached to Annexure 3. Maintenance requirements. - Schedule E – attached to Annexure 4. Design requirements as per the switchgear schedules. b. The switchgear is rated at 25kA, therefor no exhaust duct or arc absorber will be required. c. All moving parts in the switchgear and switchgear panels haves a maintenance interval of a minimum of 1 year or 5000 operations. Of particular concern are the busbar shutters and other moving parts during racking in and out of the switchgear. d. Panels are designed to contain internal arcing faults and to direct arcs and gasses arising from these up and away from the operator. e. Additional safety measures provided by the Contractor are noted in Schedule B. f. Circuit breakers and contactors are mounted in the switchboard with the same type of finishing. g. All access doors and covers to live compartments are padlockable. h. Multi-tier mounting of switchgear is not permissible. i. 5.1.2 On the new 6,6kV Ash Water Plant Boards 1 & 2, all incomer and interconnector circuits (Panel, panel covers and panel doors) are powder coated “RED”. Operating Service Requirements Compliance with the power stations operating philosophy and conditions is the minimum requirement. The requirements of 32-846 “Operating regulations for high voltage systems” are mandatory. In addition to the requirements, the following normal and abnormal conditions apply during which all the safety requirements of the Internal Arc Classified (IAC) switchgear and controlgear are met: REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 11 CAMDEN POWER STATION 6,6kV SWITCHGEAR a. All substations are unmanned, but access to the substations is being carried out at regular intervals for inspection purposes, operating and fault finding. b. Nobody is allowed on switchgear that is energised. c. A fault can occur during the operating which includes the removal of trunk type switchgear from the disconnected, earthed or test position to the connected position or vice versa. d. An earth can be applied to a live circuit. e. A low voltage compartment fault finding actions can be performed with the switchgear and controlgear in the live state. f. Voltage transformers can be racked out with the switchboard in the live state. g. A cable can be terminated in an isolated cable compartment with the switchboard being alive (Includes busbars and adjacent circuits). 5.1.3 Internal Arc Classification a. The 6,6kV switchgear, vacuum circuit breakers and controlgear are designed to confine the internal arc for fault currents as specified in Schedule A attached to Annexure 1. b. The design of the new boards is such that all direct arcs and gasses arising from these faults are guided upward away from personnel. Care in the design is taken to prevent the gases from exiting on the sides of the end panels of the boards. c. Each power compartment is able to withstand and contain the internal fault arc and shall release the pressure upwards, without the arc spreading or pressure released into any other power compartment. d. Each functional unit is designed to contain the arc without spreading it to any other functional unit. e. The design of the switchgear and controlgear is safe at the front, on the sides and at the back to enable operating while the switchgear is in operation. f. Internal arc type testing in the circuit breaker and busbar compartment ar carried out, with the low voltage compartment door open. This reason being to enable safe fault finding, operating and maintenance access to the low voltage compartment while the circuit breaker and busbar compartments are alive. Due to the internal arc classification and for maintenance purposes, no voltage transformers or earthing switches are installed within the pressure relief area on top of any functional unit. g. Where cable terminations are protruding the floor, a fire seal with a rating 2 hour are maintained. The seal is at least 50mm thick. h. For switchgear and controlgear with circuit breakers supplied from two independent supplies, the design prevents an internal arc to spread from one side of the circuit breaker connecting arms to the other side of the REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 12 CAMDEN POWER STATION 6,6kV SWITCHGEAR circuit breaker connecting arms (circuit breaker in service position but open position and both sides of the circuit breaker alive from two independent supplies). If the design does not comply with this requirement it shall be highlighted in the deviation schedule. 5.1.4 i. The designation of the IAC classification in terms of SANS 62271-200 is AFLR and the test current is equal to the busbar short circuit current specified in Schedule A attached to Annexure 1 and the internal arc duration for any internal arc is 1 second. j. If arc eliminator technology is available, it can be offered. Segregation of Compartments 5.1.4.1 General The following is the minimum with regards to segregation of compartments: a. Circuit breakers (Withdrawable or not). b. Main busbars. c. Low voltage compartment including low voltage cabling. d. Power cable termination compartment (Including earth switch and cable VT). e. Busbar earthing g device compartment. f. Busbar VT compartment. 5.1.4.2 Low Voltage Compartments a. The low voltage compartments are located in the front top section of the functional unit. b. The design of the LV compartment are such that it will house all the protection, control and monitoring functionalities as specified in this specification. c. The HMI (Human Man Interface) are located on the compartment door and all other facilities are accessible from the front of the panel. d. The compartment door has a swing frame design and is adequately supported by means hinges. e. The LV compartment doors design allows for control/protection cabling from the top or bottom of the panel. 5.1.4.3 Power Cable Compartment a. The power cable termination and cable current transformer are accessible from the cable compartment. b. The design of the compartment is such that the power cable terminations and current transformers can be easily disconnected/removed/replaced with the busbars in the energised state. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 13 CAMDEN POWER STATION 6,6kV SWITCHGEAR c. The power cable compartment complies with SANS 876 and provides for three-core cable terminations. d. The stipulations of ORHVS 32-846 are taken into account when the cable compartment is designed. e. The design is such that a fault/flash-over in this compartment shall not damage to rear power cable compartment or rear power cable compartment cover. 5.1.4.4 Main Busbar Compartment a. The main busbar compartment houses the main busbars and the busbar support structures. b. The main busbar compartment is only accessible if the provisions of OHVRS 32-846 are met. 5.1.4.5 Circuit Breaker Compartment a. Each panel is equipped with a circuit breaker compartment to house the circuit breaker. b. The design of the circuit breaker compartment is such that only circuit breaker with the same ratings can be interchanged into a circuit breaker compartment. c. Circuit breakers are of the withdrawable type and the circuit breaker compartments are designed to cater for this requirement. d. Circuit breaker compartments are operator-accessible as per interlocking requirements. 5.1.4.6 Busbar Earth Device Compartment a. The busbar earthing device compartments are special-accessible compartments that requires the switchgear board to be isolated from all points of supply and castle key system are required to release the busbar earth before the busbar earth can be applied. The isolation requirements of ORHVS 32-846 and GGR 992 are mandatory. b. The design of the busbar earth is mechanically sound and rigid, of the fixed type and with all indications and limit switches to indicate the position of the busbar earth. c. The busbar earthing device is in the same panel as the busbar VT. d. The busbar earth is operated from the front of the panel. e. The lockout system that is installed is such that the incomer circuit breakers cannot be engaged without the busbar earth in the “OFF” position. f. Withdrawable busbar earth is not acceptable. 5.1.4.7 VT Compartments (Busbar and Cable) a. VT’s are of the withdrawable type. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 14 CAMDEN POWER STATION 6,6kV SWITCHGEAR b. The VT’s are housed in it’s own panel/compartment. c. Access to the VT’s whilst in the energised position are not possible. d. The switchboard must be isolated to remove the busbar VT. This must be incorporated in the design of the switchboard. e. The cable VT’s cannot be accessed without isolating the circuit to which the cable VT is connected. This must be incorporated in the design of the switchboard. 5.1.4.8 Service Continuity Classification The loss of service category for the new switchboards is LSC2B in accordance with the requirements of SANS 62271-200. 5.1.4.9 Partition Class a. Partition class of the new switchboards is class PM as per SANS 62271-200. b. The circuit breaker compartments are equipped with busbar and cable shutters that will close when the circuit breaker is withdrawn and open when the circuit breaker is racked in. 5.1.4.10 Special labelling for Internal Arc Proof Switchboards a. Functional units (Switchboards) are so designed that the blow (Due to internal fault) will be to the top of the functional unit to satisfy IAC requirements, then the switchboards are equipped with labels to provide warning messages to persons working on the panels/switchboards. b. The following labels are displayed: - “DO NOT CLIMB ON THE SWITCHGEAR WHEN ENERGISED”. The labels are installed on the rear and sides of the switchboards. The amount of labels is dependent on the length of the panel and approval from the employer about the amount of signs is obtained. - “DO NOT STEP ON PRESSURE RELIEF FLAPS”. This sign is displayed on every functional unit of the switchboard on top of the flap. c. Warning labels are red lettering on a white background. d. The size of the signs is such that it can be clearly seen when a person is standing in the upright position. 5.1.4.11 Cooling a. The use of forced cooling is not allowed. b. Cooling of the switchgear is natural dispersion through the switchgear metal structure. 5.1.4.12 Degree of protection a. Minimum required degree of protection for the functional units is IP41. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 15 CAMDEN POWER STATION 6,6kV SWITCHGEAR b. Minimum required degree of protection for the external housing units is IP3XB. 5.1.4.13 Panel Fasteners, Doors and covers a. Fasteners used in the functional units are the same material and construction that was used in the Type Tested panels. No deviations. b. When a fastener is also a locking mechanism, provisions are made for a padlock with dimensions as per Eskom drawing 0.00-002839. c. If lift off covers is part of the design with regards to the cable compartment, it is designed such that a mechanical interlock will prevent the cover from being removed. The caver can only be removed when a cable earth is applied. d. All circuit breaker compartment or VT compartment doors are equipped with a front window that is part of the type testing for internal arc compliance. The window is part of the type and routine test certificates and seal tightly to prevent moisture and dust ingress. e. All cable compartments covers other that those housing a cable VT is fitted with bolted covers. f. Empty compartments in busbar extension dummy panels are fitted with bolted covers. g. Where doors are fitted on empty compartments, the doors are padlockable. 5.1.4.14 Corrosion Protection a. Steelwork shall be corrosion protected in accordance with the specification 240-75655504, Corrosion Protection Standard for new Indoor and Outdoor Eskom Equipment Components, Materials and Structures from Steel Standard. b. The colour of the final coating shall be in accordance with SANS 1091. 5.1.4.15 Colour Coding a. Colour coding of the new boards is Local B32, Imported RAL 2000. b. The incomer circuits and the switchboard interconnectors are coded “RED”. 5.1.4.16 Busbars and Connections a. The main busbars compartment and connections inside the busbar compartment are of the air insulated type and the clearances do not compromise the specified voltage withstand levels. b. Busbars and connections are covered up with insulating shrouding. c. The busbars are supplied as per the type tested arrangement, including any additional insulation shrouding that were used. d. Cables are not allowed to be used for busbars or busbar connections inside the circuit breaker, voltage transformer or inside busbar compartments. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 16 CAMDEN POWER STATION 6,6kV SWITCHGEAR e. All busbars are marked in such a way that they are easily identifiable as to the phase or pole they are connected to when covers are removed. The phase identification marking material is not easily removable. f. It is recommended to use heat shrink tube for marking however, the material used for marking the busbars is subject to Eskom acceptance. g. Busbar connections are made with at least two bolts and the overlap is sufficient to ensure ample mechanical strength and joint conductivity and is having the same electrical characteristics as the main busbar. The busbar connections match those of the type tested panel. h. Silver tinted or tinted copper joint interfaces are preferred for connections on busbars. i. The busbar compartments and where possible busbar connections are sealed to avoid ingress of contaminants that might degrade the connection. j. Design information relating to the type tested and routine tested busbar components is made available during tenders to clarify the materials, manufacturing method, design and manufacturing location for these components. 5.1.4.17 Spouts, Bushings and Insulators a. Moulded type bushings and spouts are used as connections between circuit breaker and busbars (Cable side and Main busbars side). b. The permissible levels of partial discharge are in accordance with SANS 62271 – 200. c. All type and routine test documentation is made available during tenders to clarify the materials used, manufacturing method, design and manufacturing locations for these components. 5.1.4.18 Insulating Materials a. The insulation material are identical (Same material characteristics and size) to the material used during voltage withstand and temperature rise type testing. b. Insulating materials can be used in areas where the insulation level criteria cannot be met with air as an insulating medium. c. Where insulation on busbars is required, it is of the heat shrink type and correct size with non-static characteristics. d. Where insulating barriers are required, the material used is of a non-static type. e. Where covers on main power connections are used, they are of the correct size, easily removable and of robust insulating materials to allow ease of inspection and maintenance. f. Clamping covers with robust insulating bolts and nuts are preferred as to not disturb the busbar connection when the busbars are inspected. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 17 CAMDEN POWER STATION 6,6kV SWITCHGEAR 5.1.4.19 Auxiliary Wiring a. The wiring, terminals, lugs, identification and installation shall be in accordance with 0.00-10341, Sheets 1 to 4 and the requirements of this specification. b. All current transformer circuits are wired with PVC 7 strand 4mm² (or multi strand 2,5mm²) copper wire. The control and voltage transformer circuits are wired such that the voltage drop does not exceed 1,5% under any conditions. c. CT and VT wiring shall be coloured as per the phase - red, white, blue and black (neutral). d. CT wiring: Wiring between the current transformer and the low voltage compartment terminals shall be coloured as per the phases – red, white, blue and black (neutral) with wire numbers. e. VT wiring: Wiring between the voltage transformer and the first fuse shall be coloured as per the phases. After the first fuse the AC wiring shall be all black with wire numbers. f. Bus wiring associated with control and voltage transformer circuits is sized to ensure that voltage limits specified in Schedule A and the current carrying capacity are not exceeded during the most onerous duty cycle. g. Alphanumeric ferrule codes are provided on all wire ends shown on the standard current transformer and voltage transformer circuits and on all bus wires. All LV wiring is done as per drawing 0.00-10341, Sheets 3 & 4. h. Bus wiring is terminated on one side of the terminals only. The wiring from the left panel is the rear lug and that from the right panel the front lug. This leaves one side of the terminals free for individual panel use only. If more than two wires are required to be connected on the bus wiring side of the terminal, an extra set of terminals is placed next to the first two, with bridge pieces to provide connection points. i. Ferrules with wire identification numbers read from left to right (the right way up) on vertical terminal strips and from top to bottom in all other cases (refer to drawing 0.00-10341, Sheets 3 & 4). The wire numbering rules as stated in of NRS 003 are not applicable. j. Stripping of insulation is done in such a way that conductors are not damaged. The stripping tool is of the type that permits the length of the strip to be pre-set. k. The crimping tool does not release the termination during normal operating until the crimp is correctly formed. l. All wire ends are terminated using crimp type lugs as detailed on drawing 0.0010341, Sheets 3 & 4. Not more than two conductors are connected to any single side of a terminal. m. For control wiring each wire tail is of sufficient length to reach the allocated equipment plus an additional length of 50mm to facilitate changes in wiring. The slack appears as close as possible to the component in the form of a loop. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 18 CAMDEN POWER STATION 6,6kV SWITCHGEAR n. Wiring presents a neat appearance and is braced and placed in PVC trunking to prevent vibration and the possibility of forces being exerted on termination arrangements. Where only a few wires have to be braced (excluding panel doors) ‘wash line’ supports are used, no stick on plastic bracing supports is allowed. o. Wires to plant and material on swing doors are so arranged as to give a twisting motion and not a bending motion to wires. p. Wiring passing from the control panel to the control cable compartment does not pass through live compartments. The totally enclosed metal duct is easily accessible and metal ducts passing over the top of the cable/busbar compartment must have removable top (not side) covers. q. Wires passing through holes in compartments are protected by means of neoprene grommets. Bevelling of sheet steel is not acceptable as a substitute. r. Wiring which are passing through a live compartment ie cable, busbar etc; are totally enclosed within a metal duct. Where this wiring is connected to current transformers adequate protection is provided. Protection for CT and VT wiring are discussed with the employer and approval is obtained from the employer. s. Control wire sheaths are coloured as follows: - Black for AC circuits - Grey for DC circuits - CT and VT wiring are coloured as per the phase - red, white, blue and black (neutral). After the first fuse the AC wiring is all black. Dielectric (insulation withstand) test of all wiring is conducted using 2,5kV to earth for 60 seconds. - 5.1.5 Power Cable Entry and termination 5.1.5.1 Power Cable Termination a. The cable compartments are adequately sized to allow for termination in air. b. The distance between cable termination points and adjacent structures within the compartment shall be in accordance with SANS 876. c. Provision shall be made to allow for the termination of multiple cables per phase. It is required to always provide one termination flag per cable to be terminated. d. Allowance shall be made inside the cable compartment to install the termination kits for XLPE MV cables of the same voltage rating as the panel, unless otherwise specified. e. All cable fixing bolts and cable lug fixing holes are provided. This arrangement, together with that for fixing the cable lug to the busbar dropper tail, is clarified with the Employer prior to proceeding with manufacture. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 19 CAMDEN POWER STATION 6,6kV SWITCHGEAR f. Provision is made for terminating all 6,6kV cables using heat shrink terminations. Cable lug fixing holes are provided as per drawing 0.00/10341, sheets 1 & 2. Heat shrink termination kits and cable lugs do not form part of this contract. This arrangement, together with that for fixing the cable lugs to the busbar dropper tails, is discussed with the cabling contractor prior to proceeding with manufacture. This arrangement is to the Employer’s acceptance. g. The distance from the gland plate or floor to the terminal points is adequate to allow crossing of cable cores for correct phase sequencing. h. With three core MV cables, adequate depth in the cable termination compartment is provided to allow for tandem cable entry rather than side-byside entry. i. Provision is made to allow for the bolting of cable lugs of multiple cables to adequately spread termination points with no more than two cables bolting to one point i.e. one on the front and one on the back of the termination bar. j. Earthing of cable core screens and wire armouring to the earth bar is provided for. 5.1.5.2 Gland Plates a. Gland plates are of adequately thickness, cover the total area in the bottom of the panel, and are mechanically sound and rigid for the cable size. b. The gland plates are adequately bolted to provide a mechanical sound and rigid installation. c. If single core cables are used, the gland plates are manufactured from aluminium. d. Number of gland plates for medium voltage cables is required as clarified with the Employer prior to proceeding with manufacture. 5.1.5.3 Cable Entry Arrangements a. Cable entries are in accordance with the minimum requirements as per the SANS 876: distance from terminal centre line to gland plate or cable clamp (if applicable). b. Any through wall plates or gland plates mounted between the bushing centre line and cable clamps, are a minimum distance of 800mm from the bushing centre line to the through wall plate or gland plate to allow for standard Eskom three core cable terminations, unless otherwise specified. c. The provisions of Eskom document 240-56227573, Air-Insulated Withdrawable AC Metal-Enclosed Switchgear and Control Gear for Rated Voltages above 1kV up to and including 52kV Standard, Section 5.1.15.3 applies. 5.1.5.4 Vermin and Fire Proofing of Cable Compartment and LV Compartment a. All cable termination compartments are designed to be sealed off with a 2 hour fire retardant material of at least 50mm thick at floor level, after the REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 20 CAMDEN POWER STATION 6,6kV SWITCHGEAR cables have been installed, to ensure the IAC integrity of the cable compartment is maintained. b. The space provided beneath the switchgear panel in the trench or cable rack allows for the installation of fire retardant material, to the extent that during an internal arc in the cable compartment, no pressure release or any smoke or heat to the front of the panel, the rear of the panel, into the cable trench, onto the cable rack or tunnel or any adjacent compartments and functional units will be possible.. 5.1.6 Earthing a. Holes in the switchgear panels provided for connecting the station earth to the switchboard earthing bar inside the switchgear panels. b. The switchboard earth bar does not protrude the side walls of the outside last panel. c. Provision is made for the switchboard earth bar to be connected to the station earth mat at least at both ends of the board. d. If the switchboard exceeds 15m in length, it is connected to the station earth in at least three places. e. The earth bar is adequately sized to carry the total fault current of the switchboard. For any earth bar, it is required to provide 25mm wide earth bar with a suitable thickness calculated to provide an equivalent fault current carrying capacity of at least 200A/mm2. f. 5.1.7 All doors and covers shall be earthed to ensure that the touch potential does not exceed the safe values as specified in the SANS 10142, Part 1 & 2 and OHS Act 85 of 1993. SPECIAL CONSIDERATION FOR INTERNAL ARC PROOF DESIGN a. Pressure relief flaps in a power compartment are designed such that the gasses are not directed to any other compartment during an internal arc fault. b. Each functional unit contains the arc without spreading it to any other functional unit. c. Due to the internal arc classification and for maintenance purposes, no VTs or earthing devices are installed within the pressure relief area on top of any functional unit. d. All switchboards with a fault rating of 31.5kA and above are equipped and type tested with exhausting ducts to channel the hot gasses generated by internal arc fault to the outside of the substation. All applicable type test and routine test reports and type test videos are provided during tender evaluations. e. The design of switchboard with a fault rating below 31.5kA allows for venting to the inside of the substation switchgear room subject to Eskom’s acceptance. In such a case, proof of type test reports and type test videos are submitted for Eskom tender evaluations. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 21 CAMDEN POWER STATION 6,6kV SWITCHGEAR f. Substations with soft ceilings and/or windows, venting is directed to the outside of the substation via the exhausting duct. g. IAC requirements are upheld while working in the low voltage compartment. Hence, the channels or conduits between the power compartments and the low voltage compartments are sealed accordingly and type tested with the LV compartment door removed. 5.2 Protection 5.2.1 General a. The contractor designs the protection system in conjunction with these stipulations, specifications and submits to Eskom for approval. b. The standard circuit design facilitates the integration of signals from the CT’s and VT’s and the interface with circuit breakers to perform various functions such as protection, control, alarm and monitoring. c. The IED that can perform at least control, indication and protection functionalities is used. d. The IED is also linked to the circuit breakers and earth switches for intertripping and interlocking functions where required. e. The control circuit is protected as per proven Eskom practice. The Contractor ensures that there is adequate co-ordination grading between the mcb’s in the control circuit and also the feeder from the DC supply. 5.3 Intelligent Electronic Devices 5.3.1 Design and Construction a. Protection schemes for all the power circuits (i.e. incomers, feeders and others) consist of IEDs constructed as a 19 inch rack mountable unit or according to Contractor's standard arrangement. No terminals are provided on the 19 inch rack. Where required, the tails are suitably ferruled with a minimum length of two meters. b. All IEDs are equipped with screen or display facility to allow for human interface. The contents are clearly visible from a distance of 2m and at an angle of 30° from either side. This display is of the Liquid Crystal Display (LCD) with anti-glare and non-blinking properties. The IED’s display makes it possible for the mimic of the circuit protected by the device to be illustrated on the display. The mimic shows as a minimum the status of circuit breakers (ON or OFF), status of earth switches, position of circuit breaker (connected or disconnected) and electrical parameters (voltage, current, power, etc.) for a particular circuit. The mimic should also display an interlock on a device if present. c. Provision is made for the local control of the breakers to be performed from the associated IED using an integrated control pad for local test purposes during maintenance only. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 22 CAMDEN POWER STATION 6,6kV SWITCHGEAR d. LED’s are required for indication of the operation of the alarm and protection functions within the IED and are an integral part of the device. The allocation of the LED’s to the different functionality is configurable to allow for flexibility during the engineering phase. e. Split face IED’s, whereby the digital display is mounted on the door of the LV compartment and connected to the main processing unit by means of fibre optic cable, are preferred. f. The devices are equipped with ports to allow for access to information via a communication link. These ports have the capacity that matches the data transfer requirements for the associated communication bus. g. A label stating the firmware version is fixed to all IED’s. Information regarding the estimated data retention time of the storage medium used in the IED’s is provided to the Employer. 5.3.2 Functions a. The protection, control, indication and data capturing functionalities are provided by the IED’s. All functions, settings and internal logic are programmable through the IED software and a personal computer (PC), except where otherwise stated. b. The Contractor specifies and gives written details of protection functionalities that are inherently part of their IED’s but are not required by the performance specification. c. A single IED is able to provide all the required main and back-up protection functions for the scheme in question as a minimum. The control and indication functions are also incorporated in the IED’s. d. The integration of the auxiliary functions such as the DC Fail and Trip Circuit Supervision (TCS) functions within the device is preferred. The IED’s have a self-monitoring function of both integral hardware and software that is done on a continuous basis. Any fault or irregularity is immediately alarmed to an output contact. e. The random switching of the DC auxiliary supplies at high rate does not affect the functionality of the IED. Where required, the internal battery requirements for numerical IED’s (i.e. battery lifetime, type of battery etc.) is stated on a label attached to the front of the numerical device. f. Unless otherwise specified, all IED’s are provided with manual-reset operation indicators for each function of the IED. These do not operate until the IED’s have operated. Resetting is accomplished without opening the case. g. The IED’s have disturbance or event recording and data logging capability with the integral storage media. The information stored in the IED is accessible via the communication port. Information regarding the estimated data retention time of storage medium of the IEDs is provided to the Employer. h. All IED’s have the capability to perform control, indication or monitoring, interlocking and data transfer functions via a communication bus. The IED’s communication capability complies with IEC 61850 standard. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 23 CAMDEN POWER STATION 6,6kV SWITCHGEAR 5.3.3 Software a. Software installed on the IED’s for event or disturbance recordings, data logging, settings and marshalling or configuration is accessible via a dedicated communication link using engineering tools. This software allows information to be downloaded in COMTRADE format in accordance with IEEE C37.111-1991. All software required to perform the marshalling and settings of the IED’s is contained in one package. b. The Contractor supplies evidence, on request, in the form of reports from a mutually acceptable third party that an adequate formal specification for the software has been produced. The specification is based on a requirement document and comprehensive risk analysis. The software is formally verified to ensure that it matches its specification. c. All software purchased on any contract and subsequent software upgrades supports the latest Microsoft Windows operating system. The Contractor informs the Employer of any and all new releases. The latest software version is always compatible with the installed base of IED’s, which originally were compatible with the previous version of software that was compatible with the previous Microsoft Windows operating system. For example, if the existing software is only compatible with Windows 95, it is upgraded to Windows 7 (the latest Microsoft supported operating system). d. All software and firmware are backward and forward compatible (i.e. the software for this contract is such that all future versions of software will be compatible with the installed base of IED’s). 5.3.4 Analogue Voltage and Current Inputs a. The current inputs of the devices are rated at 1A. b. Where required, the voltage inputs are rated at 110V AC, unless otherwise stated. c. The IED is also provided with the digital inputs for the control and indication functions as determined by the schemes. d. The configuration of the inputs is programmable. The minimum number of inputs required is provided in the C&I Interface Signals for MV Switchgear. 5.3.5 Output Contacts a. All output contacts of the IED’s have self-resetting capabilities, except for those linked to master trip and lockout functions, which have manual-reset capabilities. b. Each protection scheme has at least two output contacts for tripping. c. The IED is also provided with the digital outputs for the control and indication functions as determined by the schemes. d. The configuration of the device’s outputs is programmable. The minimum number of outputs required is provided in the C&I Interface Signals for MV Switchgear. Where required, some of the trip, alarm and indication outputs are channelled via the communication ports. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 24 CAMDEN POWER STATION 6,6kV SWITCHGEAR e. DC Fail and under voltage protection functions are facilitated by normally closed contacts. All other relays have normally open contacts. 5.3.6 Testing of Devices a. The protection devices are subjected to routine and type tests which cover at least the tests recommended in standard 32-333. The program of routine and type tests is submitted to the Project Manager for acceptance. b. Unless otherwise specified, all IED’s are provided with suitable test facilities for VT and CT circuits to enable tests carried out on the IED’s while in position inside the panel without disconnecting any wiring or links. Test facilities are provided in accordance with standard 240-56358929, Standard for Electronic Protection and Fault Monitoring Equipment for Power Systems. c. Two copies of all test certificates are submitted to the Employer for acceptance on completion of the tests. 5.3.7 Buszone Protection Relay a. The latest Eskom approved relay list applies and is adhered to with the selection of the relay types. b. Bus zone protection is implemented by utilising a numerical differential relay. These devices comply with the requirements of 240-56358929, Standard for Electronic Protection and Fault Monitoring Equipment for Power Systems as a minimum. c. Only a low impedance scheme is acceptable. The Contractor provides details of the CT requirements. CT selection methodology is required to be submitted to the employer for acceptance. d. All devices are fitted with contacts which are self-resetting with exception of the tripping function. e. The devices are provided with hand-reset operation indicators for each of the functions. The indicators do not operate until the relays have closed their contacts. Re-setting is accomplished without opening the case. f. The protection schemes are provided with suitable test facilities to enable tests to be carried out on the device while in position on the panel without disconnecting any wiring. g. The bus zone protection equipment is housed in separate panels designed to accommodate 482.6mm (19 inch) type racks or the Contractor’s standard arrangement. The panels are constructed in accordance with Eskom Standard number 240-56358929, Standard for Electronic Protection and Fault Monitoring Equipment for Power Systems. h. Auxiliary power for the bus zone protection device will be provided by the Employer at 220VDC nominal voltage rating from an external DC power supply system. The AC power supply for the cubicle lighting will also be provided by the Employer. i. DC line filters are installed in the bus zone system such that it protects the electronic components against voltage spikes. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 25 CAMDEN POWER STATION 6,6kV SWITCHGEAR 5.4 Arc Detection System 5.4.1 Protection Relays a. The arc protection function is provided by a device that accepts both light and current signals as input. These signals are detected simultaneously to initiate a trip and alarm. b. The arc protection relay performs the high speed tripping of the supply circuit breaker in the event of an arc fault when the current exceeds a pre-set reference value. The device have a maximum sensor detection function pulse delay time of less than 5ms and subsequently issues a breaker trip pulse in a time of less than 10ms from fault inception. The total (including breaker and arcing time) fault clearance time required is less than 100ms from fault inception. c. All devices are fitted with contacts which are self-resetting with exception of the tripping function. d. DC line filters are installed in the arc detection system such that they protect the electronic components against voltage spikes. 5.4.2 Light Sensors a. Arc detection is performed with light sensitive type elements located in the respective switchgear chambers (including segregated busbars between panels). The elements are installed in such a way that they completely cover the space to be protected. b. The light sensors are not triggered by external light sources such as camera flashes or welding arcs. c. The sensor has the degree of protection to operate within the boards’ internal environmental conditions. 5.4.3 Monitoring a. The internal arc protection system has a self-diagnostic (self-monitoring) function that prevents the relays from operating if a system (i.e. devices and sensors) fault is detected. It clearly indicates by means of an alarm indicator the fault and the location thereof. b. The system gives an indication of the fault location (i.e. which compartment faulted) locally at the switchgear panel through an IED and remotely on the dedicated engineering station. c. The power supply modules are continuously monitored and should provide an alarm in the event of failure. 5.4.4 Auxiliary Relays a. Where required, the auxiliary relays are provided with the desired trip or indication function with the operation time of less than 50ms. The auxiliary relays must comply with the requirements of 240-56358929, Standard for Electronic Protection and Fault Monitoring Equipment for Power Systems. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 26 CAMDEN POWER STATION 6,6kV SWITCHGEAR b. Unless otherwise specified, all the relays are provided with manual-reset operation indicator/s for the dedicated function. The indicator/s does not operate until the relay has operated. Resetting is accomplished without opening the case. c. Each relay has at least two output contacts for tripping and two output contacts for external alarms. 5.5 Protection Schemes 5.5.1 Motor Protection Scheme (Motors ≥ 1 MW) a. Protection scheme is provided for all feeders to the MV motors with power rating larger or equal to 1MW. Each scheme includes the following functions: - motor differential protection, - three-phase thermal overload protection, - three-phase definite time overcurrent protection, - three-phase IDMTL overcurrent protection, - definite time earth fault element, - IDMTL earth fault protection. - negative phase sequence protection, - three phase undervoltage protection, - motor stall protection element. b. In addition, the schemes have binary Input/output (I/O) facilities as well as analogue outputs. These input facilities are for external trip and close signals and to enable thermistors to decrease the tripping time of the overload elements. The trip outputs are latched. c. The protection elements have setting ranges. The characteristic curves of IDMTL overcurrent and earth fault protection elements conform to IEC standards. d. Thermal overload protection monitors the current flowing into the motor. Based on these currents, it models the temperature inside the motor. e. Negative phase sequence protection function is made available in the motor protection scheme. This function protects the motor against overheating caused by induced double frequency currents. The negative phase protection has an inverse and a definite time characteristics. f. Motor stall protection function is available in the motor protection scheme. This function is preferably an overcurrent protection element set below the locked rotor current and a time delay set to the stall capability time of the motor. The time delay is adjustable over the range. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 27 CAMDEN POWER STATION 6,6kV SWITCHGEAR g. Three-phase definite time undervoltage protection function is made available in the motor protection scheme. This function does not operate for the loss of a single-phase VT supply but only operates for the loss of all three phases after a predetermined period. The undervoltage protection function trips the motors for a sustained under voltage condition. The protection elements are energized from voltage transformers with secondary of 110V phase-to-phase and 63.5V phase-to-neutral. The elements are adjustable to operate in the voltage ranges and have drop-off/pick-up ratios greater than 95%. Setting adjustment is preferably continuously variable, but if adjusted in steps, these do not exceed 10%. The time delay is adjustable over the range. h. Other functions required in the motor protection scheme such as current interlock, long starting time, etc. are indicated in. i. 5.5.2 The Contractor provides output analogue signals (i.e. current and power) from the IED’s. The Contractor provides separate measurement modules (i.e. transducers) for both current and power. Alternatively, the measurement modules are provided as an integral part of the protection IED in accordance with 240-56535964, Generation MV and LV Protection Philosophy for Eskom Power Stations. The Contractor also provides in the Rates Price Schedule both the take out price for having separate measurement modules, as well as the price for transducers provided as an integral part of the IED. MV Interconnector Protection Scheme a. Interconnector protection schemes include the following functions: - line differential protection, - three-phase definite time overcurrent protection, - three-phase IDMTL overcurrent protection, - definite time earth fault protection, and - IDMTL earth fault protection. b. The overcurrent and earth fault elements (i.e. IDMTL or definite time) are set as main protection for the interconnector and back-up protection for downstream circuits. c. The Contractor specifies and supplies the fibre optic or pilot wire cables, which are suitable for the cable differential protection, to be installed by the Employer. Fibre optic links are preferred for differential protection application. d. A synchronism check facility is provided for the changing of power supplies on a MV board, which is feeding from different sources. The synchronism check facility measures the three phase voltage quantities from the cable and busbar VT’s. Once the three voltages are the same, in phase, magnitude, phase rotation and frequency, a closing signal is issued to the breaker of the normal supply and an open to the alternative supply after a period not exceeding 100ms. This is done to ensure the make-before-break operation. Different set parameters are required. e. A typical switching or operating procedure for the power transfer is as follows: Close the unit supply breaker (with unit supply cable VT alive) to energize the REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 28 CAMDEN POWER STATION 6,6kV SWITCHGEAR busbar (busbar VT dead and station supply breaker opened with station supply breaker cable VT dead). Vice versa is also applicable. This is a ‘Live line’, dead bus charge. f. The protection elements have setting ranges. The characteristic curves of IDMTL overcurrent and earth fault protection elements conform to IEC standards. g. The Contractor provides output analogue signals (i.e. current and voltage) from the IED’s. These measurement modules are an integral part of the protection IED in accordance with 240-56535964, Generation MV and LV Protection Philosophy for Eskom Power Stations. The Contractor also provides a takeout price for having separate measurement modules (i.e. transducers) in the Rates Price Schedule. 5.5.3 Transformer Feeder Protection Scheme (Transformer < 10 MVA) a. Protection scheme for the feeders of the transformer with the power rating smaller than 10MVA includes the following functions: - three-phase definite time overcurrent protection, - three-phase IDMTL overcurrent protection, - definite time earth fault protection, and - IDMTL earth fault protection. b. The IDMTL overcurrent and earth fault are set as main protection for the transformer / feeder and back-up protection for downstream circuits. c. In addition, the IED’s have binary input facilities. These input facilities cater for external alarm and trip signals such as Buchholz, winding temperature, oil temperature and pressure relief protection. A minimum of eight binary inputs are required. d. The protection elements have setting ranges. The characteristic curves of IDMTL overcurrent and earth fault protection elements conform to IEC standards. e. The Contractor provides output analogue signals (i.e. current) from the IED’s. These measurement modules are an integral part of the protection IED in accordance with 240-56535964, Generation MV and LV Protection Philosophy for Eskom Power Stations. The Contractor also provides a takeout price for having separate measurement modules (i.e. transducers) in the Rates Price Schedule. 5.5.4 MV Incomer Protection a. Incomer protection scheme have the following functions: - three-phase definite time undervoltage protection, - three-phase definite time overcurrent protection, - three-phase IDMTL overcurrent protection, REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 29 CAMDEN POWER STATION 6,6kV SWITCHGEAR - definite time earth fault protection, - IDMTL earth fault protection. b. The overcurrent and earth fault protection is utilised to provide the required current input for the arc detection interlock and also act as back-up protection for downstream circuits. c. A synchronism check facility is provided for the changing of power supplies on a MV board, which is feeding from different sources. The synchronism check facility measures the three phase voltage quantities from the cable and busbar VTs. Once the three voltages are the same in phase, magnitude, phase rotation and frequency, a closing signal is issued to the breaker of the normal supply and an open to the alternative supply after a period not exceeding 100ms. This is done to ensure the make-before-break operation. Different set parameters are required. d. A typical switching or operating procedure for the power transfer is as follows: Close the unit supply breaker (with unit supply cable VT alive) to energize the busbar (busbar VT dead and station supply breaker opened with station supply breaker cable VT dead). Vice versa is also applicable. This is a ‘Live line’, dead bus charge. e. In addition, the IED’s have binary input and output facilities in accordance with the scheme requirements for external trip signals. f. The protection elements have setting ranges. The characteristic curves of IDMTL overcurrent and earth fault protection elements conform to IEC standards. g. The Contractor provides output analogue signals (i.e. current and voltage) from the IED’s. These measurement modules are an integral part of the protection IED in accordance with 240-56535964, Generation MV and LV Protection Philosophy for Eskom Power Stations. The Contractor also provides a takeout price for having separate measurement modules (i.e. transducers) in the Rates Price Schedule. 5.6 Arc Protection Scheme 5.6.1 General a. The system protects the segregated breaker, busbar and cable chamber respectively in the case of an internal arc fault for air insulated MV switchgear. b. The main protection device is mounted on the board incomer panels with the auxiliary devices in different panels as required. 5.6.2 Current Detection Methods a. A three-phase CT connection from the board incomer or upstream feeder overcurrent and/or earth fault function is provided together with an arc sensing device (two-out-of-two measuring criteria). The current rating of the input to the device is 1A. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 30 CAMDEN POWER STATION 6,6kV SWITCHGEAR b. An overcurrent or earth fault signal is activated once the current on any one phase exceeds the reference values. This function has the capability to capture and display the three phase currents that caused the protection operation. The system is able to provide arc protection with low fault currents as well (i.e. smaller than 4kA fault current). c. Detection of overcurrent conditions is implemented to increase the stability of the detection system under normal conditions. This feature ensures that the system does not act on incidents where light is emitted without the existence of excessive current in the circuit concerned. 5.6.3 Circuit Breaker Failure Protection a. The circuit breaker failure protection facility is provided by the arc protection system to trip the upstream feeder circuit breaker in case of an incomer breaker failure. b. A time delay of 100ms is allowed for the main circuit breaker to operate before the breaker fail protection operates the upstream circuit breaker. c. The total tripping time does not exceed the switchgear internal arc test time, Tt (as defined in SANS 62271-200). 5.6.4 Busbar Chamber Protection a. The function of this application is to detect and clear internal arc faults in the busbar chamber on a particular board. When any of the light sensors on the board detect an arc together with an overcurrent or earth fault current on the incomer feeder, it trips the incomer feeder, bus section breaker and all the feeder circuit breakers of the relevant zone. b. The internal arc detection devices are applied to overlap in the bus section chamber, thus tripping only the faulty zone for an internal arc fault in the bus section chamber. 5.6.5 Protection of Circuit Breaker Compartment a. The function of this application is to detect and clear internal arc faults in the circuit breaker chamber. b. Where multiple tripping is required the arc sensing devices detect an arc together with an overcurrent or earth fault current from the incomer feeder, it trips the incomer feeder, bus section breaker and all the feeder circuit breakers of the relevant zone. 5.6.6 Protection of Cable Termination Compartments 5.6.6.1 Feeders a. The function of this application is to detect and clear internal arc faults in the feeder cable chamber. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 31 CAMDEN POWER STATION 6,6kV SWITCHGEAR b. Where multiple tripping is required the arc sensing devices detect an arc together with an over current or earth fault current from the incomer feeder it trips the incomer feeder, bus section breaker and all the feeder circuit breakers of the relevant zone. 5.6.6.2 Incomers a. The function of this application is to detect and clear internal arc faults in the incomer cable chamber. b. Where multiple tripping is required the arc sensing devices detect an arc together with an over current from the upstream feeder it trips the upstream feeder circuit breaker. 5.6.7 Buszone Protection Scheme a. The bus zone protection scheme is designed to protect the breaker, busbar and cable chamber respectively in the case of a three phase bolted fault for air insulated MV switchgear. The protection scheme is based on basic operation principles of low impedance differential current measuring system. b. The function of the bus zone protection system is to perform fast clearance of phase to phase and phase to earth faults. The supply breaker and all feeder breakers are tripped in the event of a fault and current exceeding a pre-set reference value. c. A check feature such as integral circuit supervision is included to prevent tripping of bus-zone protection if any of the current transformer circuits become disconnected during normal load conditions. Alarm contacts operate under these conditions to initiate a remote alarm. d. A testing system, consisting of current isolation and measuring facilities at the input from each current transformer, and facilities for short-circuiting the current transformer circuits, when they are isolated from the protection system, is included. e. The detailed system description (i.e. specification, layouts and circuit diagrams) and test procedures for the bus-zone protection system is provided in the tender documents. f. The Project Manager may request the Contractor to check whether the bus zone protection is stable under external fault conditions. g. The protection CT core is fed onto standard switchgear terminals and then to the CT test block and protection device measuring elements with overlapping of the bus section CT cores. h. The boards requiring single or double zone tripping. 5.6.8 DC Fail Function a. DC Fail function is provided to monitor the DC supplies of all the protection schemes at the last supply point. This functionality can either be incorporated in the IED, if a separate power supply is available, or a dedicated auxiliary relay. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 32 CAMDEN POWER STATION 6,6kV SWITCHGEAR b. The function allows for operating on loss of DC voltage. Alarm output signal is also transmitted to the DCS system and indicated on the IED, if separate suppliers are used. 5.7 Circuit Breakers 5.7.1 General a. Circuit-breakers are of the triple-pole withdrawal type with visible indication of the circuit breaker state, which is mechanically interlocked with the circuitbreaker. b. The arc-quenching medium and/or insulation are of the type as specified. c. No oil circuit breakers are acceptable. d. Withdrawable circuit breakers are housed in a circuit-breaker compartment of the panel. The design is of the behind close door design. e. Emergency operating of the circuit-breaker complies with the behind close door design. f. Total current interruption (break) time as defined in SANS 62271-100 is not greater than the time duration specified, under all operating conditions. g. Where circuit-breakers are used, the power connecting arms are fully insulated. Bare copper as connecting arms are not acceptable. h. Where bus-zone protection is required, the bus-section circuit-breaker design shall allow for the installation of current transformers on each side of the bussection circuit- breaker. i. Where vacuum interrupters/SF6 are used in the circuit-breaker design, only the type tested vacuum interrupter design or product specific code as per the type test report designation shall be offered during tender evaluation. j. Circuit breakers are provided as per the scope of work of these specifications. 5.7.2 Inter-changeability a. Circuit breakers with the same current rating, type and auxiliary contact configuration are interchangeable. b. It is not possible to interchange a circuit breaker with a lower current rating into a compartment with a higher current rating. 5.7.3 Circuit-breaker truck connections a. Where the auxiliary connections between the circuit-breaker truck or trolley and the circuit breaker compartment are made by means of flexible connections, these are contained in a flexible conduit. b. If metallic conduit is provided, this shall be covered by an approved insulating material, however non-metallic robust flexible conduit is preferred. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 33 CAMDEN POWER STATION 6,6kV SWITCHGEAR c. A means is provided to retain the flexible connection out of the path of the circuit-breaker when the truck or trolley is inserted into and removed from the circuit breaker compartment. 5.7.4 Shutters a. Automatically-operated shutters are provided so that on racking out the circuit-breaker, these shutters cover the busbar and circuit spouts automatically and fully to prevent inadvertent contact with live busbars and circuits. b. Circuit spouts shutters are arranged to operate independently from the busbar spout shutters. c. These shutters are capable of being padlocked in the open and closed position. d. Shutters operate without lubrication and are constructed in such a manner as to ensure fail-safe operation. e. Shutter endurance and reliability is proven by type testing to the number of operations as specified in Schedule A attached to Annexure 1. f. Busbar spout shutters are colour coded red and labelled with the word “BUSBAR” in black letters at least 50mm high. g. Circuit spout shutters are coloured yellow and labelled with the word “CIRCUIT” in black letters at least 50mm high. h. Shutters are of robust, rigid and durable design and is capable of the lasting the live of the switchgear. i. 5.7.5 Busbar and circuit shutters operate smoothly without the aid of lubricants. Mechanisms a. Mechanisms as per SANS 62271-1, SANS 62271-100, SANS 62271-102 and SANS 62271-200 are provided. b. All conventional circuit-breakers and actuator circuit-breakers electricallyoperated closing devices including mechanism charging motors are suitable for operation at any voltage between 85% and 110% of nominal control voltage measured at the terminals of the device. c. The circuit-breaker closes correctly when an electrical closing pulse of 100ms duration is applied to the closing coil. d. The total power drawn by the closing coil, excluding closing solenoids, does not exceed 1200VA per circuit-breaker. e. All operating coils of solenoid coil contactors are continuously rated, and the contacts are rated for a short duration in accordance with the current drawn for the operating time. f. A normally-closed auxiliary contact is to be wired in series with the closing coil REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 34 CAMDEN POWER STATION 6,6kV SWITCHGEAR 5.7.6 Tripping Devices a. All conventional circuit-breakers and actuator circuit-breakers electric tripping devices are of the shunt type, suitable for operating at any voltage between 85% and 110% of the rated control voltage measured at the device terminals. b. Two normally-open auxiliary contacts in parallel are included per tripping circuit in series with the trip coil. c. Circuit-breakers design makes provision for the installation of a second tripping coil as per the voltage specified. This second trip coil forms an integral part of the design of the circuit-breaker complete with interlocking. d. Circuit-breakers design makes provision for the installation of an under voltage release coil as per the voltage specified. e. This under voltage release coil forms an integral part of the design of the circuit-breaker complete with interlocking operating below 35% of nominal voltage. 5.7.7 Indicating Devices a. A positive driven mechanical indicating device to show whether the circuitbreaker is open or closed is provided. The devices are labelled as follows: - ON or I - white lettering on a red background - OFF or O - white lettering on a green background b. Lettering size shall not be less than 10mm, are easily readable and cannot be removed unless force is applied. c. The method of securing the labels is as per the requirements of this specification. d. Where the circuit-breaker position is not visible from the front of the panel, a positive driven mechanical indicator is provided to indicate whether the circuit-breaker is in the service or disconnected position, or state the position of the integral-connected disconnectors, whichever is applicable. e. All mechanical indicators shall be clearly visible from the front of the panel and are type tested for the number of operations of the operating device to prove the reliability of the indicating mechanism. 5.7.8 Auxiliary Contacts a. Auxiliary contacts of the circuit breaker are readily accessible and the preference is contacts with a pronounced wiping action. b. Sufficient auxiliary contacts are provided as per the schematic drawings and the requirements for spare contacts. c. The spare contacts are easily convertible from normally open to normally closed and vice versa and are wired to the outgoing control terminals. d. Auxiliary contacts positively follow the action of the main contacts. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 35 CAMDEN POWER STATION 6,6kV SWITCHGEAR e. Suitable arrangements are made to ensure that circuit-breaker auxiliary contacts only signal the change of state when the circuit-breaker is in the service and disconnected position. f. 5.7.9 Where insufficient contacts are available, a continuously rated slave relay are provided but is used for indication circuits only. Control Connector a. Control connectors are of the multi-pin design with removable pins for male and female connectors. b. Where connectors are of the off load design, this implies that the control circuit are designed to take into consideration easy isolation of all supplies to the circuit-breaker to connect or disconnect the control connector off load. c. Control connectors have the facility to be coded to differentiate between different circuit-breaker types, ratings and functions or protection schemes for the same rated circuit-breakers. 5.7.10 Insulation Level a. The insulation level of all circuit-breakers, busbars, busbar connections and any other related components are in accordance with the values specified. b. The use of insulation material barriers for phase segregation to increase the insulation level are not acceptable if not type tested. Documented proof is supplied to the employer. c. No insulation material are used that may lead to material ageing and degradation for the insulation levels specified over time, or may lead to partial discharge of the panel due to ageing or possible dust collection. d. Where insulating materials are part of the integral design of the switchgear, the life expectancy is guaranteed by means of testing where applicable and material data sheets for the prescribed installation conditions. 5.8 Earthing Devices 5.8.1 General a. The switchgear design includes busbar and cable earthing devices as an integral part of the associated functional unit/switchgear board. b. Earthing devices are an earthing switch function except for cases where the circuit-breaker is used as the earthing making device. c. All earthing devices are operated from the front and outside of the panel. No other method allowed. d. Provisions are made for a mechanism that enables padlocking in both the “ON” and “OFF” positions to inhibit operation of the earthing devices. e. Interlocks are provided in accordance with SANS 62271-200. f. Earthing of cables or busbars via the enclosure and supporting structures are be acceptable. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 36 CAMDEN POWER STATION 6,6kV SWITCHGEAR g. The earthing device position indicator is visible from the front of the panel. A positive driven mechanical indicating device to show whether the earthing device is open or closed is provided. h. Earthing devices are of sound and robust design. 5.8.2 Busbar Earthing Devices a. Busbar earthing devices are provided for the main busbars of the switchgear boards. b. Busbar earthing devices are used to provide connection between all three phases of the main busbars and main earth bar through isolating bushings where applicable. c. The busbar earthing device may not be mounted in the busbar compartment. d. It is not possible to connect the main busbars to earth if the main busbars are alive. Provisions are made to accommodate this requirement. e. A positive driven mechanical indicating device to show whether the main busbar earth is applied or not is provided. The devices are labelled as follows: f. ON or I - white lettering on a red background OFF or O - white lettering on a green background Lettering size shall not be less than 10mm, are easily readable and cannot be removed unless force is applied. g. The method of securing the labels is as per the requirements of this specification. 5.8.3 Cable Earthing Device a. Cable earthing switches are provided for all incoming and feeder, motor drive and transformer circuit panels. b. Interlocking is required for the cable earthing device to be applied before the cable compartment door or cover can be opened. c. Interlocking is also be provided for utilizing the cable live indication system (VDS) to prevent closing of the earthing switch onto live cables. d. Cable earthing devices are connected between all three phases of the cable terminals and main earth bar. e. A positive driven mechanical indicating device to show whether the cable earth is applied or not is provided. The devices are labelled as follows: f. - ON or I - white lettering on a red background - OFF or O - white lettering on a green background Lettering size shall not be less than 10mm, are easily readable and cannot be removed unless force is applied. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 37 CAMDEN POWER STATION 6,6kV SWITCHGEAR g. The method of securing the labels is as per the requirements of this specification. 5.9 ACCESSORIES 5.9.1 Current Transformers a. Each functional unit is equipped with current transformers. b. Current transformers comply with SANS 61869-2. c. Current transformers are installed inside the associated functional unit such that they are easily accessible and removable. Their mounting arrangements are such that it does not interfere with the cable connecting arrangements. d. The short-time withstand current rating of current transformers are not be less than that of the associated circuit-breaker. e. Secondary windings of current transformers are earthed at one point only. f. Each group of current transformers (i.e. protection, metering etc.) are earthed to the earth bar using isolating links. The isolating links is not be removable from the terminal. g. All current transformers are of air-cooled design and the cooling is through natural flow of air. h. Additional rating plates made of a durable material are provided with markings as per SANS 61869-2. i. The securing of the name plates is rigid and sound. Glue is not acceptable as a medium to secure the nameplates. j. The information on the additional rating plates is duplicated from that appearing on each current transformer and is located within the low voltage compartment in a position giving easy visibility and on the inside of the cable compartment. k. The phase colour with which each current transformer is associated appears beneath each rating plate. 5.9.2 Voltage Transformer a. VT’s comply with SANS 61869-3. b. VT’s are of the resin encapsulated type and air-cooled design. The cooling is through natural flow of air. c. VT’s are of the single-phase design, where applicable for motor starter panels. d. Busbar connected VT’s panels are of the withdrawable type and cable VT’s are of the fixed type. No primary fuses are required for fixed type cable VT’s. e. VT’s are interchangeable for individual phases. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 38 CAMDEN POWER STATION 6,6kV SWITCHGEAR f. The primary side of busbar connected VT panels are connected to the busbars via adequately rated HRC fuses. It is not possible to gain access to these HRC fuses with the VT in the service position. g. The busbar connected VT is of the plug-in type and arranged such that it can be isolated and removed without affecting the associated circuits. h. When VT’s are withdrawn, the spouts are closable by means of automatic shutters. The shutters shall have padlocking facilities. i. Provision are made to enable locking of the busbar connected VT in the “service” position. j. All VT’s are star primary and star secondary connected. earthed at both the primary and secondary star points. The VT’s are k. The circuit on the secondary side of the VT is protected with the use of either fuses or mcb’s. l. The protection devices are mounted on the VT in order to include the wiring from the VT to the LV compartment in the protected circuit. m. The secondary fuses of the cable VT is easily accessible without any danger of having to work in a live chamber. No fuses or mcb’s are fitted in a phasecircuit that is connected to earth. n. The VT is connected to the earth bar by means of isolating links. isolating links are removable from the terminal by use of a tool. The o. The links are accessible and safe to remove with the VT racked out. 5.9.3 Indicating and Measurement Instruments a. All instruments are of the flush-mounting industrial type in accordance with IEC 60051 for indicating instruments of Class 1.5 category. b. Instrument test blocks/terminals are provided on the front of the relevant low voltage compartment to facilitate connecting of external instruments in the various current and voltage transformers secondary circuits. c. Test blocks/terminals have terminal strips and links for performing the various short-circuiting and bridging functions. d. Test blocks/terminals have removable covers, which are secured in position. e. The type of test block that will be used are approved by the employer. f. Transducers shall conform to IEC 60688. g. Transducers are of the type approved by the employer and are available on the market for the lifetime of the switchgear. 5.9.4 Selector Switches a. Selector switch are of the pistol-grip type. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 39 CAMDEN POWER STATION 6,6kV SWITCHGEAR b. The selector switches complies with 240-56358929. 5.9.5 Cable Live Indicators a. Cable live indicators are installed on all outgoing and incoming cable and transformer circuits. b. Cable live indicators comply with SANS 61243-5. c. Cable live indicators are of the fixed type. 5.10 Terminals 5.10.1 Material and Construction Terminals are in accordance with 240-56358929, of the types as shown on drawing 0.00-10341 Sheet 1 and 0.00-10341 Sheet 3 and adhering to the limitations as indicated on the drawing. 5.10.2 Mounting Rail mounted terminal blocks comply with the requirements for the dimensions of mounting rails in accordance with 240-56358929. 5.10.3 Types a. The terminal types are selected for voltage and current rating application in accordance with Eskom document/drawing 240-56358929. b. Instrument test blocks or terminals are provided in the relevant low voltage compartment to facilitate connecting of external instruments in the various current and voltage transformer secondary circuits. c. The test block or terminals are accessible from the front of the terminal without opening the low voltage compartment door. d. Test blocks and terminals have terminal strips and links for performing the various short-circuiting and bridging functions. e. Test blocks and terminals are equipped removable covers, which are secured in position. 5.10.4 Wiring and Cable Lugs a. Control wiring lugs and their application with different types of terminals are in accordance with 240-56358929 and as detailed on Drawing 0.00-10341 Sheets 1 to 4. b. Crimping on of power lugs are in accordance with BS 4579. c. Crimping tools specifications. are re-calibrated according to their manufacturer’s d. The crimped area shall be equal to the conductor square area. e. With the lug in position, no bare copper are visible after the crimp. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 40 CAMDEN POWER STATION 6,6kV SWITCHGEAR f. Wiring presents a neat and professional appearance. 5.11 Labels a. All labels are in accordance with labelling specifications found in 0.00-10343 Sheets 1 and 2. b. Labels are inscribed in English. c. The content of the label shall be provided by Eskom following the relevant plant codification standard. 5.12 Nameplates a. Each switchboard is provided with a nameplate which complies with the specifications found in 0.00-10343 Sheets 1 and 2. b. The nameplate covers the following: - Manufacturer. - Date of manufacture. - Fault level of the board’s main busbars. - IP rating of the board. - Rating of the main busbars. I - Rated voltage Ur - Rated lightning impulse withstand voltage 2) Up - Rated switching impulse withstand voltage 2) Us - Rated power-frequency withstand voltage2) Ud - Rated normal current Ir - Rated short-time withstand current Ik - Rated peak withstand current Ip - Rated frequency fr - Rated duration of short circuit tk - Rated auxiliary voltage Ua - Rated filling pressure (density) for insulation pre (ρ re) - Rated filling pressure (density) for operation prm ( ρrm) - Alarm pressure (density) for insulation pae (ρae) - Alarm pressure (density) for operation pam (ρam) - Minimum functional pressure (density) for insulation pme (ρme) - Minimum functional pressure (density) for operation pmm (ρmm) kA c. The nameplates are secured on the incomer circuit of each board. d. The securing of the nameplates are done in such a way that force must be applied to remove the nameplate. e. Glue is not an acceptable method of securing the nameplates. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 41 CAMDEN POWER STATION 6,6kV SWITCHGEAR 5.13 SWITCHGEAR INTERLOCKING SYSTEMS Mechanical interlocks are provided for the withdrawable circuit-breakers to ensure that: a. The circuit-breaker can only be engaged and disengaged to/from the service position when the circuit-breaker main contacts are fully open. b. The circuit-breaker can only be operated when it is in the service, or disconnected/withdrawn position. c. The circuit-breaker compartment front door is trapped in the close position and cannot be removed/opened when the circuit-breaker is in the service position and during racking of the circuit-breaker. d. Integral earth switches, if fitted, cannot be closed unless the circuit-breaker is in the disconnected position and cable VDS indication is dead. e. Busbar selection in a switchboard, if applicable, is only possible when the circuit-breaker is open. f. For flexible auxiliary connections, the multi-pin connector must be engaged and the control supply switched on to enable the circuit-breaker to be placed in the service position. g. Circuit-breakers cannot be closed or racked into service position unless the cable earth switch is in the open position. h. Busbar earthing is only possible when all busbar supply, board interconnecting circuit-breakers and circuit-breakers of transformer feeders are in the disconnected position. i. With the circuit-breaker in the disconnected position and the circuit-breaker compartment door open the circuit-breaker cannot be moved from the disconnected position to the service position. j. The cable compartment door can only be open if the earth switch is in the earthed position (i.e. earth switch applied). k. The requirements for non-mechanical interlocks shall conform to required operating philosophy presented by Eskom, defined schematic drawings and SANS 62271-200. l. Where blocking magnets are used as part of the system interlocking, the rating of the blocking magnets shall be continuously rated and shall comply with the control voltage rating and variations. m. Where electrical system interlocking is preferred, the details shall be specified by Eskom. n. Where castle keys are used, the provisions of these specifications are taking preference. - The design of the castle key system are such that the incomer circuit breaker, the interconnector circuit breakers of both boards and the transformer circuits that are in a RM circuit must be isolated before a busbar earth can be applied. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 42 CAMDEN POWER STATION 6,6kV SWITCHGEAR 5.14 Testing and Documentation of Test Reports 5.14.1 Type Test a. Only type tested functional units are acceptable for use in this project. The type tests are carried out on all types of functional units in accordance with SANS 62271-200. b. The electrical components affecting the performance of the functional unit shall be type tested in accordance with the relevant parts of SANS 62271 and other applicable standards. The components shall be tested to be in compliance with Eskom specification. c. CT’s shall be type tested in accordance with SANS 61869-2. d. VT’s shall be type tested in accordance with SANS 61869-3. e. Cable live indicators are type tested in accordance with SANS 61243-5. f. The tested functional unit and associated components are a credible representation of the equipment under consideration. g. Type test authorities for switchgear and controlgear are accredited in accordance with ISO 17025. h. All type tests are supplied to Camden Power Station to be verified and accepted by Camden Power Station before manufacturing can start. i. It is the manufacturer and supplier responsibility to submit all type test reports for the specific switchgear types and ratings offered. j. If the offered product is not 100% the same for the design, material, manufacturing method and manufacturing location as was type tested, the switchgear will not be accepted. 5.14.2 3.9.2 Routine Tests a. Routine tests are performed on each of the functional units and associated components. b. Routine tests are conducted in a reputable testing facility that is acceptable to Camden PowerStation. c. Switchgear and controlgear are tested in accordance with the relevant parts of SANS 62271. d. CT’s shall be tested in accordance with SANS 61869-2. e. VT’s shall be tested in accordance with SANS 61869-3. f. All the other components forming part of the functional unit are tested in accordance with the applicable standards to prove functionality and compliance with the relevant Eskom specifications. 5.14.3 Special Tests REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 43 CAMDEN POWER STATION 6,6kV SWITCHGEAR The following special tests shall be performed on all types of switchgear designs: 5.14.3.1 Mechanical Impact Test The mechanical impact test is carried out on all types of functional units in accordance with SANS 62271-200. 5.14.3.2 Partial Discharge Test a. The partial discharge tests are carried out on all types of functional units in accordance with SANS 62271-200. b. Internal Arc Compliance with LV compartment door in the open position. c. The internal arc tests are carried out in accordance with SANS 62271-200 with the LV compartment door open. d. The duration of the internal arc test shall be 1 second. e. The tests are carried out on all power compartments, which are busbar, circuit-breaker and cable compartment. f. Type test authorities used to perform special tests are accredited in accordance with ISO 17025. g. All special tests compliance are verified and accepted by Camden Power Station. h. For prototype panels, full range of the required routine tests are conducted and witnessed by Eskom. 5.15 MAINTENANCE AND OPERATION 5.15.1 Maintenance and Operating Tools a. Any special tools or keys that may be required for maintenance, operating or for adjustments are provided. b. Handling equipment or trolleys are provided to facilitate the removal of the mid-mount withdrawable devices from the panel. c. The trolleys are of mechanical sound and robust design, equipped with guards or guard rails to prevent the circuit breaker from damage when the circuit breaker is withdrawn. d. The trolley wheels are able to take up the full loading of the circuit breaker and of durable material. e. Two trolleys are supplied with each board. f. Special tools such as cable earth handles, racking in/out handles and panel keys; the employer requires 3 for each board. g. A tool cabinet is supplied with each board which will house the special tools. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 44 CAMDEN POWER STATION 6,6kV SWITCHGEAR 5.15.2 Maintenance and Operating Instructions a. The works instructions or procedures are provided to the employer by the original equipment manufacturer (OEM) detailing descriptions of the maintenance and operating work in accordance with BS 6626 and SANS 62271-1. b. The procedures cover the requirements for maintenance and operating of the equipment over the design life. c. It is required during tenders to develop and submit to Eskom a failure mode effect and criticality analysis (FMECA) to identify all maintenance requirements and end of life criteria for the panel types offered. 5.16 DOCUMENTATION 5.16.1 Language All documentation, including reports, manuals, etc. are in the English language. 5.16.2 Type Test Reports a. Type test documentation represents the design of the functional unit with respect to the configuration, type and rating. b. The information to be included in type test reports is in accordance with SANS 62271-200. c. The report of the type tested functional unit and associated components reflect the equipment under consideration. d. The type test report provided in full, containing all records of the tests conducted as well as the drawings. e. Softcopies are provided for all type test documentation. 5.17 Manuals and Drawings a. The technical, training, maintenance and operating manuals are provided for each type (e.g. for different ratings, voltage levels etc.) of a functional unit. b. Technical manuals include all technical data, information on the switchgear construction as well as the technical data and leaflets of each individual component used in the switchgear provided and are subject orientated of the plant installed. c. Where generic manuals are provided, an addendum is provided indicating the applicable project specific components. d. Manuals and drawings are of a good quality and shall cover the following as a minimum: - Technical descriptions of the equipment and component parts - General arrangement drawings REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 45 CAMDEN POWER STATION 6,6kV SWITCHGEAR - Installation instructions with drawings or pictures - Operating and maintenance instructions for all components - Detailed parts lists (accompanied by exploded view type drawings clearly detailing the part and uniquely identifying it) - Spare part ordering instructions e. Any special instructions pertaining to storage as spare parts or as shelf life are included in the maintenance manual. f. All drawings requested for component location, dismantling and re-assembly for maintenance are included in the maintenance manual. g. All special tools required for operating and maintenance of the equipment are presented in a form of a schedule in the operating and maintenance manual, respectively. h. The content of the training manual shall be based on the content of the technical, operating and maintenance manuals. 5.18 PACKAGING, TRANSPORTATION AND HANDLING a. The functional units are suitable for handling and removal by providing mechanisms for crane hooks. b. The functional unit is suitable for handling and removal by providing mechanisms to avoid damage to the functional unit. c. During transportation the electrical components are packaged in such a way that damage is prevented. d. Components of the functional unit that are transported separately are marked accordingly and shall be easily identifiable. REQUIREMENTS FOR THE WORKS SUPPLIED BY THE CONTRACTOR Page 46