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EVENT LOGGER Contd.. Process of Data Down Load Data Down Load to Station Monitoring System EVENT LOGGER Contd.. Data Down Load for ABB make Relay INDACTIC 425 EVENT LOGGER Contd.. Data Down Load for Siemens make Relay 7SA522--series DISTURBANCE RECORDER What is Disturbance Recorder? Why is it required for Sub-Station? Functions of disturbance Recorder Records the sequential data events. Provides the status of power systems Pre and post fault data of parameters Information of the disturbances Analysis of values in wave form or vectorial form . DISTURBANCE RECORDER Contd… Basic Principle of Disturbance recorder: Initiation of Digital or Analog pulse due to disturbance Sampling of the pulse for data acquisition. Buffer is used to distinguish the pre and post fault condition of disturbance Time stamped for correct sequence DI signal filter is used for correct memory storage Data becomes ready for communicable DISTURBANCE RECORDER Contd… DISTURBANCE RECORDER Contd… Application and Settings of Disturbance recorder: Setting through HMI or PC Selection of Binary Inputs and logical out puts for the relay action. Application for Trip Analysis and event analysis. Selection of Electrical Equipments for correct action . FAULT LOCATOR What is Fault Locator? Why is it required for Sub-Station? Functions of fault Locator Records the fault data . Pre and post fault data of parameters Locates and indicates the distance of fault occurrence. SUB STATION OPERATIONAL CONCEPTS Equi-Potential Concept: Synchronization Charging: Parallel Network Charging Power flow Calculation Parallel Operation of Transformer Interlock Scheme MF for Indicating meters: Under frequency Load Shedding Concept System Islanding Pole Discrepancy concept LBB Concept Auto reclose Concept Concepts on Ground OPERATIONAL CONCEPTS Equi-Potential Concept: Operation for Change to Transfer Bus Equi-potential Concept 89A B A A B C 52L D A B C 52T 52B B PT1 C 52L D PT2 Parallel Operation for Bus Change Over 89A B A A B C 52L D B PT1 C 52T C 52L 52B D B PT2 OPERATIONAL CONCEPTS Contd.. Synchronization Charging PT1 29M 25 52L 29L 29T PT2 OPERATIONAL CONCEPTS Contd.. Power flow Calculation Thumb rule Current = (600 x MVA)/ KV Actual rule Current = (577 x MVA) / KV OPERATIONAL CONCEPTS Contd.. Parallel Operation of Transformer CONDITIONS FOR PARALLEL OPERATION Same vector group. ,Same voltage ratio Same frequency, Same polarity Same phase rotation LOAD SHARING For two Transformers PA = P (QA.ZB) / (ZA.QB + ZB.QA), PB = P (QB.ZA) / (ZA.QB + ZB.QA) For 3 Transformers PA = P (QA.ZB ZC) / , P (QC.ZA.ZB) / PB = P (QB.ZC ZA) / , Pc = Where = (QA.ZB ZC + QB.ZC ZA + QC.ZA.ZB) Parallel Operation of Transformer Concepts on Contacts and Position of Switch N I 1 3 5 T 2 4 6 7 8 9 10 Inter lock Concept: Applications for CBs, isolators and earth switches Can be electrical , mechanical or electromechanical or combined Circuit Breaker:- Not allowed to operate if adjacent isolators are in operation Isolators No operation on power current or interconnection of different voltage system. No operation when CB in series in close , adjacent Earth switch on close condition Making or breaking of paralleling circuits is permitted Earth Switch Earth switches may only be operated if the isolators on both sides are open. Only an open CB is not enough DIFFERENT BUS ARRANGEMENT.. L1 29M B1 52B1 B2 52B2 52L 29L Single Bus System Ring Bus System 29M 52L 29M1 29M1 52B 29MB2 52B 29M2 29L 29T 29MB1 29T1 29 L1 22 B 52 L 29 L2 Main and Transfer Bus Two Bus System 29MA 52A 29LA 29TA 52T 29TB 29LB 52B 29MB Two Bus and Transfer System One and Half System Arrangement for Main and Transfer Bus Scheme All Bay 29 T Open 29E T 29M1 29M 52L 29T I/L 52B 52B 29L N I 29E 29T 29T1 52B 52L OPERATIONAL CONCEPTS Contd.. MF for Indicating meters Example1 :- Meter data CTR=-/1, PTR=11KV/110 Line CTR=400/1, PTR=33KV/110, So MF=1200 Example2:- Meter data CTR=-/5, PTR=-/110 Line CTR=400/1, PTR=11KV/110, So MF=200000 OPERATIONAL CONCEPTS Contd.. Under Frequency Load Shedding Load Load Load Load Load Load Load Load Load Load OPERATIONAL CONCEPTS Contd.. System Islanding Scheme Load Load Load Load Load Load Load Load Load Pole Discrepancy Concepts Applicable to the Individual pole operated Breaker. A B C A B C LBB Concepts 89A B 52L A B C 52L D A D B A B C 52T PT1 C 52L D PT2 Auto reclose Concept . Auto reclosing principles SETTING CRITERIA Dead Time Auto- reclosing requires a dead time which exceeds the deionising time Time required for the de-ionising of the fault path depends on:- arcing time, fault duration, wind conditions, circuit voltage, capacitive coupling to adjacent conductors, etc. Single phase dead time of 1.0 sec is recommended for both 400kV and 220kV system. Minimum Dead Time (IEEE) System Voltage kV 23 46 69 115 132 230 345 400 500 Minimum deionization time [ms] Based on Field Based on and Operating Laboratory Experience Tests 110 180 120 200 130 210 150 230 160 240 210 280 260 340 280 370 330 420 SETTING CRITERIA Reclaim Time The time during which a new start of the auto-reclosing equipment is blocked. If reclosing shot has been carried out and the line is energized and a new fault occurs before the reclaim time has elapsed, the auto-reclosing equipment is blocked and a signal for definite tripping of the breaker is obtained. After the reclaim time has elapsed, the auto-reclosing equipment returns to the starting position and a new reclosing sequence can occur. The reclaim time must not be set to such a low value that the intended operating cycle of the breaker is exceeded, when two faults incidents occur close together. If the breaker is closed manually, the auto reclosing equipment is blocked and cannot start again until the reclaim time has elapsed. For the breaker to be used for auto-reclosing, it is essential that it has the operating mechanism and breaking capacity necessary for it to be able to perform the auto-reclosing sequences required. The recommended operating cycle at 400kV and 220kV is as per the IEC standard. Reclaim time of 25 sec is recommended Concept on Ground in the system Gound fault in Unground system VR V R1 VR V RY V RY1 V BR N N V Y1 VB V YB VY VY C C C A 120° N A A N N 82° 60° G G B Full Ground Fault on Phase B B B No Ground Fault 50% Ground Fault on Phase B Meaning of Equipment Codes 89:52:86:67:21:30:51:95:99:81:- 89:- Isolator/ Air Break Switch 52:- Circuit Breaker 86:0 Master Relay 67:- Directional O/C Relay 21:- Distance Protection Relay 30:- Annunciation Relay 51:- Non- Directional O/C Relay 95:- Supervision Relay 99:- Over Flux Relay 81:- Frequency Relay Meaning of The Drawing Fig-A Fig-A. 1.89A can be operated when Breaker is OPEN 2.Isolator 89B can be operated when Breaker and Earth Switch are open. Explain the Protections provided to the Transformer Non- Directional Back Up Relay, Temp. Relay Current Balance Relay, Differential Relay, REF Relay, Under Voltage, Over Voltage, Voltage/Frequenc y Relay Positioning of Equipments 220 KV system LA Parallel ( Line – Earth) CVT Parallel ( Line – Earth) WAVE TRAP Series CT Series EARTH SWITCH Parallel ( Line – Earth) LINE ISO Series CB Series BUS ISOLATOR Series CT ratio Calculation I12 R1 = I22 R2 I2/I1 = (R1/R2) 1/2 I2= 200x 2/1.732 I2=231 S1 200/1 S2 Abbreviation of Terms 1. MCOV 2. NDC 3. ONAN MCOV= Maximum Continuous Operating Voltage NDC:- Nominal Discharge Current ONAN= Oil Natural Air Natural 4. HSV HSV= Highest System Voltage 5. BIL BIL= Basic Insulation Level 6. ALF 7. IEC 8. ISF 9. IS 10. TOV ALF= Accuracy Limiting Factor IEC= International Electro technical Commission IS= Indian Standard ISF= Instrument Safety Factor TOV= Temporary Over Voltage CT Connection on secondary Which Connection of CT Secondary is correct. S1 S2 R S1 Fig-1 S2 R S4 S3 S3 Fig-2 Answer Fig-1 S4 Explain the operations for Main Bus-1 Maintenance Work, considering the safety aspects in mind 89A B A A B C 52L 52B D B A B C 52T PT1 C 52L D PT2 Calculate MF of the meter One MWh Meter has data CTR=-/1, PTR=33KV/110 With Line CTR=400/1, Line PTR=33KV/110, Meter reading Advance is 20000. Calculate Million Unit energy Consumed. MF of MWh meter is 400x20000= 8,000000 Mwh So Million Unit Consumed= 8,000000x1000 unit= 8,000 Million Unit Situation for AC source mixed 1St 55th 110th -Ve + Ve +ve Terminal of 1st Cell, got connected to the phase of 1 ph AC source , What will happen to the Status of Bulb glowing L A THEORY –A B Bulb A will glow brighter and flicker may be fused Delta Connection Load and One Terminal is Earthed Draw the Vector diagram Vr R Vry Vry Vbr Vbr Y Vby B Vb Vy Vby Questions for discussion 1. What is the difference between earthing and neutral 2. Why Wave Trap is connected in Rph and Bph but not in Yph 3. Why “MW Meter” shows both +ve and –Ve reading ( i.e. Export and Import) while current (Ammeter) only shows one side reading 4. Why single break Isolator is preferable to double break isolator 5. Why auto transformer ratings are generally rated with ratio less than 2, but two windings transformer are rated more than 2 6. When two transformers are operating in different tap position is there any chance of operation of E/F or REF relay in any of the transformer 7. Why O/C relays are connected to R & B Phase but E/F relay is connected to Y Phase 8. What will happen to a CT of a feeder if its secondary was opened when feeder is idle charged and drawing no load 9. Why it is not advisable to use AR scheme for Gang operated breaker system 10. Does it need to provide Wave trap on each phase of the transmission line at the sub-station Questions for discussion 11. Why the use of combined instrument transformer is not gaining popularity in India. 12. Why the spring-spring mechanism is gaining popularity in Breaker Technology 13. Which circuit is important for supervision of breaker trip coil status?(Pre-close supervision, post-close supervision) 14 Why DC Voltage is preferable for the protection and control circuit in System Network 15. What are the reasons for variation of voltage due to increase of load in the system 16. Most of the Power transformers are of Y connected, why not ∆ connected 17. We know that Voltage is directly proportional to frequency, but sometimes voltage decreases but not the frequencies why? 18. In case of 3ph, 4wire system, and the neutral is disconnected. Why the meter showing the value above 350volts in 2 phases? 19. Why REF protection is not considered as 100% protection to the equipment winding 20. Why PT of different rating is used [110V /√3 and 110V] Questions for discussion 21. Why PS class core is best suitable for the application to Differential Relay 22. Can performance of REF relay be reduced if its residual current circuit is obtained in series with E/F relay in the scheme 23. Which protection is better, either REF protection or Differential protection for Transformer 24. Why REF relay is grouped under high impedance relay? 25. What is the significance of INTER position for a NIT switch on a feeder bay control panel. 26. Why Guard terminal is used during the measurement of IR value of electrical equipment. 27. Explain the concept for which the IR value at 30 sec becomes more than the IR value at 15 sec, for good insulator system. 28.Can the Magnetic Balance Test be considered as a signature test for transformer fault diagnosis? 29. Draw 3 Over current + E/F Relay circuit and 2 O/C + 1 E/F Relay circuit Develop REF circuit for a 3 winding Transformer Auto reclose Concept Ground fault in Un grounded System. VR V R1 VR V RY V RY1 V BR N N V Y1 VB V YB VY VY