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STUDY IN ELECTROMECHANICAL RELAYS RELIABILITY Javier Pablos Abelairas CERN TE-MPE-TM 3rd OCTOBER 2013 Outline CERN Introduction to relays Scope of the study The test bench Results Conclusions [11] TE-MPE-TM 3rd OCTOBER 2013 2 Outline CERN Introduction to relays Scope of the study The test bench Results Conclusions [11] TE-MPE-TM 3rd OCTOBER 2013 3 Relay: What is it? CERN It is an electrically operated switch that opens or closes a circuit. A very useful electrical component : • to control a high-power circuit by a low-power signal. • In circuits where several circuits must be controlled by one signal. Complete electrical isolation between control and controlled circuit Widely used electronic component in safety systems. Protective relays can prevent equipment damage by detecting electrical abnormalities, including overcurrent, undercurrent, overloads and reverse currents. At CERN there are more than 64000 protective relays in the machine TE-MPE-TM 3rd OCTOBER 2013 4 Relay: History CERN Invented in 1835 by the American scientist Joseph Henry. Developed to improve his version of the electrical telegraph, developed earlier in 1831. Relays were also used as a constructive part of some early calculators and computers. Samuel Morse used Henry's relay device to carry morsecode signals over long kilometres of wire. In 1878 the American company Western-Electric used electric relays designed by Edison in telephone systems. TE-MPE-TM 3rd OCTOBER 2013 5 Relays: Applications CERN Widely used electronic component in applications within different fields: • Telecommunications: − Antenna switches for UMTS − GSM base stations − Radio base Stations • Data communications: − Embedded modem data access arrangement − PC modem discrete DAA circuits − Radio base Stations • Industrial: − Industrial control systems − Remote monitoring − Ground isolation − Speed controls • Security Systems: − Alarm switches − Sensor switches − Safety Gate TE-MPE-TM 3rd OCTOBER 2013 6 Relays: Manufacturers CERN TE-MPE-TM 3rd OCTOBER 2013 7 Relays: Classification CERN Control Safety Relay With a contact Mechanical Relay Without a contact Hybrid Semi-Conductor Relay Mechanical and semi-conductor Relay (SSR (Solid State Relays)) The contact opens and shuts mechanically The output part is a semi-conductor and does not open and shut mechanically. TE-MPE-TM 3rd OCTOBER 2013 8 Relays: SSR vs EMR CERN Solid State Relay (SSR): electronic switching device in which the load current is conducted by semiconductors instead of mechanical contacts. The output semiconductor device (SCR, TRIAC, or transistor) is optically-coupled to a LED light source inside the relay. Electromechanical Relay (EMR): electrically operated switches that complete or interrupt a circuit by physically moving contacts mechanically. TE-MPE-TM 3rd OCTOBER 2013 9 Relays: SSR vs EMR CERN ADVANTAGES Solid State Relay SSR Electromechanical Relay EMR - Smaller size - Cheaper - Long operation life - Input and output circuit are electrically isolated - Low switching time (fast) - Lower contact resistance - Quiet operation (no acoustic noise) - Lower contact capacitance (good for HF circuits) - Electromagnetic noise resistance and low electrical interference generation. - No heat sink required - No contact arcing or bouncing. - Tend to fail in an open state - ‘Zero-cross’ circuitry for AC loads - Single input / multiple output capability. Control of several circuits - No moving parts to wear out which means it is shock and vibration resistant, improving system reliability. - Consume less power - Low input power consumption reducing heat dissipation requirements . TE-MPE-TM 3rd OCTOBER 2013 - High resistance to EMI and overvoltages - Available in extremely high voltage and current ratings 10 Relays: SSR vs EMR CERN ADVANTAGES Solid State Relay SSR Electromechanical Relay EMR - Smaller size - Cheaper - Long operation life - Input and output circuit are electrically isolated - Low switching time (fast) - Lower contact resistance - Quiet Operation (no acoustic noise) - Lower contact capacitance (good for HF circuits) - Electromagnetic noise resistance and low electrical interference generation. - No heat sink required - No contact arcing or bouncing. - Tend to fail in an open state - ‘Zero-cross’ circuitry for AC loads - Single input / multiple output capability. Control of several circuits - No moving parts to wear out meaning shock and vibration resistant, improving system reliability. - Consume less power - Low input power consumption reducing heat dissipation requirements . TE-MPE-TM 3rd OCTOBER 2013 - High resistance to EMI and overvoltages - Available in extremely high voltage and current ratings 11 Relays: EMR CERN Principle of operation: • When energized an electric current passes through the coil generating a magnetic field. • The magnetic field activates the armature towards the iron yoke. • The armature produces the movement of the contact that either makes or breaks a connection with a fixed contact • When de-energized the armature is placed back into its initial position by a spring or by gravity TE-MPE-TM 3rd OCTOBER 2013 12 Relays: Safety Relays CERN • Type of relay with forcibly guided contacts, i.e., contacts that are mechanically linked together. • Impossible that NO (normally open) and NC (normally closed) contacts could be closed at the same time. • Used in applications where safety is a requirement. • Ensure the safety function even if contacts are welded together. • Requirement of EN 50205 Standard • So called Class A Safety Relays • Mark on the nameplate TE-MPE-TM 3rd OCTOBER 2013 13 Relays: Parameters CERN Ambient Operating Temperature: Temperature measured directly in the vicinity of the relay. The maximum allowed value may not be exceeded, otherwise there is a chance for relay failure. Ambient temperature range according to IEC 61810-1 Maximum Switching frequency: Maximum switching frequency which satisfies the mechanical or electrical life under repeated operations by applying a pulse train at the rated voltage to the operating coil. Electronic symbol: COIL SPECIFICATIONS: • Coil Current: Current drawn by the coil for generating the magnetic pull force. At the moment of switching the coil on, the current is higher than in continuous use. • Coil Resistance: Electrical resistance of the coil at reference temperature. It varies with temperature. • Nominal Coil Operate Voltage: The voltage required in order to make the relay operate. • Dropout / release voltage: Voltage applied to the coil below which all the contacts of an operating relay must revert to non-operating position. TE-MPE-TM 3rd OCTOBER 2013 14 Relays: Parameters CERN Mechanical Endurance (Mechanical Life): Number of switching operations without contact load during which the relay remains within the specified characteristics. Electrical Endurance (Electrical Life): Number of switching operations until failure of a relay under defined conditions of load and of ambient influences. The reference value specified for the endurance applies to a resistive load. At lower contact loads a substantially longer electrical life is achieved. CONTACT SPECIFICATIONS: • Number of contacts • Contact Resistance: Electrical resistance between the relay terminals of a closed contact circuit, measured with nominal current and voltage. • Maximum Carrying Current: Maximum current which, after closing or prior to opening, the contacts can safely pass without being subject to temperature rise in excess of their design limit. • Maximum Switching Current: Maximum current that can safely be switched by the contacts. TE-MPE-TM 3rd OCTOBER 2013 15 Relays: Parameters CERN Contact forms: Different types of contact arrangements Form Description Short Description NARM designator Make Contact Form A NO SPST-NO Break Contact Form B NC SPST-NC Changeover Contact Form C CO SPDT Double make on armature Form U SPST-NO DM Double brake on armature Form V SPST-NC DB Double make contact Form X SPST-NO DM Double brake contact Form Y SPST-NC DB Double brake, Double make contact Form Z SPDT-NC-NO DBDM Triple make contact Form 3 TE-MPE-TM 3rd OCTOBER 2013 Circuit Symbol 16 Relays: Parameters CERN Contact material: Major influence on the performance of a relay affecting maximum inrush current, maximum switching current, contact resistance, etc. together with contact reliability and electrical life. Good electrical and thermal conductivity. Exhibits low contact resistance, but low r esistance against aggressive atmosphere. Easily Fine Grain Silver develops a sulphide film in a sulphide atmosphere. The addition of 0.15% Ni gives the alloy a greater mechanical stability reducing welding AgNi 0.15 and contact wear. Universally applicable in medium and low load range, especially in DC circuits, ≥ 12V, 10 mA Silver-Nickel AgNi10 Contact Material Surface Finish Used for switching loads in the rage of >100mA. High resistance to contact wear and low welding tendency. Slightly higher contact resistance than AgNi0.15. Mainly used in DC switching particularly in automotive applications where high inrush current occur e.g. when switching lamps. Silver-Cadmium- Very high resistance to contact wear and welding. Good thermal and mechanical stability. Particularly suited for switching inductive or high oxide current loads like motors, heating resistors, solenoids etc. High contact resistance and sulphide films form easily. AgCdO Silver-Tin-Oxide AgSnO2 Higher melting point and higher thermal stability than AgCdO and therefore greater resistance to welding. Also contact erosion rate is lower because any arc spreads to the outside of the contact preventing creation of a local hot spot and potential weld. High contact life, minimum material migration. It is mainly used for circuits with high requirements to make and break currents, DC and AC coils, like fluorescent light loads. Palladium Copper PdCu Greater hardness, low contact wear and stable contact resistance. Good corrosion and sulphidation resistance. Very low material migration compared to other contact materials. Expensive. Mainly used for Flasher applications in Automobiles. Tungsten W Highest melting point, high wear resistance with heavy loads, little transfer of material, best suited for breaking heavy inductive loads. Not recommended. Used as pre-contact in circuits with highest make and break loads ≥ 60V, 1A Rh plating (rhodium) Combines perfect corrosion resistance and hardness. As plated contacts, used for relatively light loads. In an organic gas atmosphere, care is required as polymers may develop. Therefore, it is used in hermetic sealed relays (reed relays, etc.). Expensive. Au clad (gold clad) Gold with its excellent corrosion resistance is pressure welded onto a base metal. Special characteristics are uniform thickness and the nonexistence of pinholes. Greatly effective especially for low level loads under relatively adverse atmospheres. Tungsten W The purpose is to protect the contact base metal during storage of the switch or device with built-in switch. However, a certain degree of contact stability can be obtained even when switching loads. TE-MPE-TM 3rd OCTOBER 2013 17 Relays: Parameters CERN Contact material: Major influence on the performance of a relay affecting maximum inrush current, maximum switching current, contact resistance, etc. together with contact reliability and electrical life. Good electrical and thermal conductivity. Exhibits low contact resistance, but low r esistance against aggressive atmosphere. Easily Fine Grain Silver develops a sulphide film in a sulphide atmosphere. The addition of 0.15% Ni gives the alloy a greater mechanical stability reducing welding AgNi 0.15 and contact wear. Universally applicable in medium and low load range, especially in DC circuits, ≥ 12V, 10 mA Silver-Nickel AgNi10 Contact Material Surface Finish Used for switching loads in the rage of >100mA. High resistance to contact wear and low welding tendency. Slightly higher contact resistance than AgNi0.15. Mainly used in DC switching particularly in automotive applications where high inrush current occur e.g. when switching lamps. Silver-Cadmium- Very high resistance to contact wear and welding. Good thermal and mechanical stability. Particularly suited for switching inductive or high oxide current loads like motors, heating resistors, solenoids etc. High contact resistance and sulphide films form easily. AgCdO Silver-Tin-Oxide AgSnO2 Higher melting point and higher thermal stability than AgCdO and therefore greater resistance to welding. Also contact erosion rate is lower because any arc spreads to the outside of the contact preventing creation of a local hot spot and potential weld. High contact life, minimum material migration. It is mainly used for circuits with high requirements to make and break currents, DC and AC coils, like fluorescent light loads. Palladium Copper PdCu Greater hardness, low contact wear and stable contact resistance. Good corrosion and sulphidation resistance. Very low material migration compared to other contact materials. Expensive. Mainly used for Flasher applications in Automobiles. Tungsten W Highest melting point, high wear resistance with heavy loads, little transfer of material, best suited for breaking heavy inductive loads. Not recommended. Used as pre-contact in circuits with highest make and break loads ≥ 60V, 1A Rh plating (rhodium) Combines perfect corrosion resistance and hardness. As plated contacts, used for relatively light loads. In an organic gas atmosphere, care is required as polymers may develop. Therefore, it is used in hermetic sealed relays (reed relays, etc.). Expensive. Au clad (gold clad) Gold with its excellent corrosion resistance is pressure welded onto a base metal. Special characteristics are uniform thickness and the nonexistence of pinholes. Greatly effective especially for low level loads under relatively adverse atmospheres. Tungsten W The purpose is to protect the contact base metal during storage of the switch or device with built-in switch. However, a certain degree of contact stability can be obtained even when switching loads. TE-MPE-TM 3rd OCTOBER 2013 18 Relays: Parameters CERN Relay Cycles (dynamic response): Due to the self-induction of the coil and the inertia of the parts to be moved, on activating a relay the operations do not take place suddenly: Operate time: Time from the initial application of power to the coil until the closure of the normally open contacts (excluding bounce time). • Bounce Time: Time interval between the first and final closing of a contact, caused by a mechanical shock process in contact movement (contact bounce) • Release Time / Reset Time: The time from the initial removal of power from the coil until the re-closure of the normally closed contacts. Excluding bounce time. • Transit time / Transfer Time: The movement time of the armature after opening of the one contact set (e.g. NC) before closing of the other (e.g. NO). Coil supply • Contact current 1 t Operate Time NO Contact 0 1 0 t Release Time Transit Time NC Contact Bounce Time t 1 0 CO Contact t 1 TE-MPE-TM 3rd OCTOBER 2013 19 Relays: Failures CERN Relays can fail for a variety of reasons: accidents, manufacturing defects or simply because they have reached the end of their life. Failure Mode Relative Probability Failure to trip 55% Spurious trip 26% Short 19% Most common failure mechanism: • Contamination of contacts with oxides or deposits: − Metallic: causes short conditions due to contact welding. − Non-metallic (gas): causes open circuits when material is periodically deposited. • Mechanical wear of internal switching elements (contact migration, contact pitting) • Other: Open and shorted coils, loose resiliency of the spring. Failures in the system due to safety relays: contact bounce, arcing interference with nearby electrical instruments and sensors… TE-MPE-TM 3rd OCTOBER 2013 20 Outline CERN Introduction to relays Scope of the study The test bench Results Conclusions [11] TE-MPE-TM 3rd OCTOBER 2013 21 Scope CERN Design of a remote power cycle option for the upgraded protection units DQLPU and DQGPU type B. DQLPU (Local Protection Units): Integrate the protection electronics and DAQ systems for the LHC main magnet protection. • • DQLPU DQLPU type A: MB protection, 1232 units. DQLPU type B: MQ protection, 392 units. DQGPU DQGPU type B (Global Protection Units): In charge of the protection of the Individually Powered Dipole (IPD) and the Individually Powered Quadrupole (IPQ). Future upgrades of the beam interlock system or any other protection system since they are intended to reliably monitor the signals from safety devices and switch off quickly in an emergency. TE-MPE-TM 3rd OCTOBER 2013 22 Relays in QPS CERN Crate Description Power cycle Interlock DQHDS trigger DQLPU type A MB protection Relay Relay Relay DQLPU type B MQ protection Not yet implemented Relay Relay DQLPU type S Symmetric quench and bus-bars Relay Relay / PhotoMOS Relay DQGPU type A Corrector magnets Relay (external) PhotoMOS N/A DQGPU type B Insertion region magnets (IPD, IPQ) Not implemented PhotoMOS PhotoMOS DQGPU type C Inner triplets Not implemented PhotoMOS PhotoMOS DQGPU type D HTS current leads Relay (external) PhotoMOS N/A TE-MPE-TM 3rd OCTOBER 2013 23 Outline CERN Introduction to relays Scope of the study The test bench Results Conclusions [11] TE-MPE-TM 3rd OCTOBER 2013 24 Test Bench Setup CERN • Parameter under study: mechanical endurance, contact bouncing, operate time and release time. • 3 sets of relays depending on whether they have 5V, 12V or 24V nominal coil voltage. • Relays with different contact configuration 1, 2, 4, 6, 8 poles. NI PCI-6014 Acquisition Board 16 analog Input (8 differential) 2 analog output 8 digital I / O NI CB-68LP Connector Block Relay Board 5V TE-MPE-TM 3rd OCTOBER 2013 25 Test Bench Setup CERN • Same control signal energizes all the relays so it is possible to compare different response times between relays • One output signal per relay • Schema of the electronic control circuit of a single relay of 2 poles Logic circuit gathers all the signals from the contacts. TE-MPE-TM 3rd OCTOBER 2013 26 Test Bench Setup: 5V Relays CERN Relay 11 PANASONIC Relay 12 FINDER Relay 13 SCHRACK Relay 14 SCHRACK 1 CO 1 NO 1 CO 1 NO AgSnO2 AgCdO AgSnO2 AgSnO2, gold plated 5V 5V 5V 5V Minimum Operating Voltage 3.5V 3.9V 3.5V 5V Release Voltage 0.5V 0.5V 0.25V 0.25V Coil Resistance 69.4 ± 10% Ω 125 147 ± 10% Ω 147 ± 10% Ω Dimensions L x W x H (mm) 22x16x19.9 20x10x10.7 28x5x18.5 28x5x18.5 Ambient Operating Temperature (-40) to 85oC (-40) to 85oC (-40) to 85oC (-40) to 85oC 12 6.4 6 6 Mechanical Endurance 107 operations 107 operations 107 operations 107 operations Max. Switching Current 5A 6A 6A 6A Operate / Release Time 10 / 10 ms 6 / 2 ms 12 / 5 ms 5 / 2.5 ms Brand Image Number of contacts Contact Material Rated Voltage Weight (g) TE-MPE-TM 3rd OCTOBER 2013 27 Test Bench Setup: 12V Relays CERN Relay 5 Relay 6 Relay 7 Relay 8 Relay 9 Relay 10 ELESTA RELAYS FINDER DOLD PANASONIC SCHRACK FINDER Number of contacts 4 (3NO + 1NC) 2 CO 6 (3NO + 3NC) 8 (4NO + 4NC) 6 (3NO + 3NC) 1 CO Contact Material AgSnO2 + 0.2μm Au AgSnO2 AgNi10 + 0.2μm Au Au-flashed AgSnO2 AgSnO2 + 0.2μm Au AgSnO2 Rated Voltage 12V 12V 12V 12V 12V 12V Minimum Operating Voltage 9V 9V 8.4V 9V 9V 9V Release Voltage 1.2V 1.2V 1.2V 1.8V 1.2V 1.2V Coil Resistance 140 ± 10% Ω 205 Ω 180 ± 10% Ω 288 ± 10% Ω 180 ± 10% Ω 400 Ω Dimensions L x W x H (mm) 36.1x12.5x29.1 29x12.4x30 41.5x14.5x33.2 53.3x33x19 55x16.5x19.8 19x15.5x20 Ambient Operating Temperature (-40) to 70oC (-40) to 70oC (-40) to 85oC (-40) to 70oC (-25) to 70oC (-40) to 85oC Weight (g) 25 20 38 47 30 10 Mechanical Endurance 107 operations 107 operations 5 x 107 operations 107 operations 107 operations 107 operations Max. Switching Current 8A 8A 8A 6A 8A 10A Operate / Release Time 8 / 4 ms 10 / 4 ms 20 / 6 ms 30 / 15 ms 11 / 3 ms 9 / 3 ms Brand Image TE-MPE-TM 3rd OCTOBER 2013 28 Test Bench Setup: 24V Relays CERN Relay 1 Relay 2 Relay 3 Relay 4 SCHRACK HENGSTLER OMROM HENGSTLER Number of contacts 4 (3NO + 1NC) 4 (2NO + 2NC) 6 (3NO + 3NC) 6 (4NO + 2NC) Contact Material AgSnO2 AgNi + 0.2μm Au Rated Voltage 24V 24V 24V 24V Minimum Operating Voltage 18V 18.1V 18V 15.5V Release Voltage 2.4V 4.3V 2.4V 3V Coil Resistance 720 ± 10 Ω 1020 ± 8 Ω 1152 480 ± 8 Ω Dimensions L x W x H (mm) 40x13x19.5 44.6x12.5x30 40x13x27.5 57.8x20.5x48.6 Ambient Operating Temperature (-25) to 70oC (-25) to 80oC (-20) to 70oC (-25) to 80oC Weight (g) 30 31 25 115 Mechanical Endurance 107 operations 107 operations 107 operations 107 operations Max. Switching Current 8A 8A 6A 10A Operate / Release Time 12 / 20 ms 15 / 8 ms 20 / 20 ms 17 / 7 ms Brand Image TE-MPE-TM 3rd OCTOBER 2013 AgCdO 29 CERN Test Bench Setup: Power Supply 12V 24V TE-MPE-TM 3rd OCTOBER 2013 30 Test Bench Setup CERN TE-MPE-TM 3rd OCTOBER 2013 31 Tests CERN Three different tests were executed: 1. Operate the relays to occurs their mechanical endurance to observe whether breakdown Test duration: 24 days/lot Operation frequency: 5 Hz Resolution: 1ms Number of cycles ≈ 10x106 2. Operate the relays once every 15 days to simulate a power cycle scenario. Test duration: 6 months Number of operations = 12 3. The relays were energized for 1 day (voltage applied to the coil) and afterwards operated normally for 1 day Test duration: 14 days Operation frequency: 1 Hz Number of operations ≈ 86000/day TE-MPE-TM 3rd OCTOBER 2013 32 Outline CERN Introduction to relays Scope of the study The test bench Results Conclusions [11] TE-MPE-TM 3rd OCTOBER 2013 33 CERN Results: Relay Reliability Reliability: Ability of a system or component to fulfil a certain function under stated conditions for a specified period of time. Relays do not age until switched. Reliability may be expressed as the number of switch cycles before wear-out rather than the more traditional failure rates (MTBF/MTTF). TE-MPE-TM 3rd OCTOBER 2013 34 Results: Test 1 CERN TEST 1 [11] TE-MPE-TM 3rd OCTOBER 2013 35 CERN Results: Response Times Test 1 Operate Time ∙∙∙∙∙∙∙∙∙ Release Time- TE-MPE-TM 3rd OCTOBER 2013 36 Results: Response Times Test 1 CERN • No relay breakdowns after 10x106 operations. • There is a mild rising trend in the response time of the relay over time. • Most of the relays didn’t meet the datasheet specifications provided by manufacturers. Relay Voltage Contacts Operate Time (Mean/ SD / Datasheet) Relase Time (Mean / SD / Datasheet) PANASONIC 5V 1 (CO) 5.55ms / 0.07ms / 10ms 7ms / 0.15ms / 10ms FINDER 5V 1 (NO) 5.44ms / 0.1ms / 6ms 7.97ms / 0.19ms / 2ms SCHRACK 5V 1 (CO) 4.61ms / 0.1ms / 12ms 5.2ms / 0.22ms / 5ms SCHRACK 5V 1 (NO) 5.58ms / 0.11ms / 5ms 4.78ms / 0.09ms / 2.5ms ELESTA RELAYS 12V 4 (3NO/1NC) 9.41ms / 0.15ms / 8ms 7.6ms / 0.1ms / 4ms FINDER 12V 2 (CO) 11.25ms / 0.48ms / 10ms 9.11ms / 0.3ms / 4ms DOLD 12V 6 (3NO/3NC) 16.87ms / 0.67ms / 20ms 11.43ms / 0.32ms / 6ms PANASONIC 12V 8 (4NO/4NC) 14.87ms / 0.79ms / 30ms 15.59ms / 0.31ms / 15ms SCHRACK 12V 6 (3NO/3NC) 15.66ms / 0.86ms / 11ms 6.99ms / 0.34ms / 3ms FINDER 12V 1 (CO) 14.75ms / 0.6ms / 9m 12.69ms / 0.36ms / 3ms SCHRACK 24V 4 (3NO/1NC) 9.72ms / 0.45ms / 20ms 11.5ms / 0.33ms / 12ms HENGSTLER 24V 4 (2NO/1NC) 14.4ms / 0.33ms / 15ms 12.18ms / 0.40ms / 8ms OMROM 24V 6 (3NO/3NC) 12.01ms / 0.65ms / 20ms 8 ms / 0.23ms / 20ms HENGSTLER 24V 6 (4NO/2NC) 21.78ms / 0.45ms / 17ms 18.94ms / 0.46ms / 7ms TE-MPE-TM 3rd OCTOBER 2013 37 Results: Contact Bouncing Test 1 CERN Contact bounce or chatter is a common problem with mechanical components since they are made of metals which exhibit spring-like behaviour. The use of ‘de-bouncing’ circuits eradicates this undesirable behaviour. Relay1 Voltage Contacts Operate time Bounces Percentage (over 10x106) PANASONIC 5V 1 (CO) 5.55ms 0 0 FINDER 5V 1 (NO) 5.44ms 0 0 SCHRACK 5V 1 (CO) 4.61ms 0 0 SCHRACK 5V 1 (NO) 5.58ms 0 0 ELESTA RELAYS 12V 4 (3NO/1NC) 9.41ms 13 ≈0 FINDER 12V 2 (CO) 11.25ms 47 ≈0 DOLD 12V 6 (3NO/3NC) 16.87ms 114356 1.14 PANASONIC 12V 8 (4NO/4NC) 14.87ms 45365 0.45 SCHRACK 12V 6 (3NO/3NC) 15.66ms 0 0 FINDER 12V 1 (CO) 14.75ms 456 0.004 SCHRACK 24V 4 (3NO/1NC) 9.72ms 0 0 HENGSTLER 24V 4 (2NO/1NC) 14.4ms 23 ≈0 OMROM 24V 6 (3NO/3NC) 12.01ms 34678 0.34 HENGSTLER 24V 6 (4NO/2NC) 21.78ms 69841 0.69 TE-MPE-TM 3rd OCTOBER 2013 38 Results: Test 2 CERN TEST 2 [11] TE-MPE-TM 3rd OCTOBER 2013 39 CERN Results: Response Times Test 2 Operate Time ∙∙∙∙∙∙∙∙∙ Release Time- TE-MPE-TM 3rd OCTOBER 2013 40 Results: Response Times Test 2 CERN The results show that after a period of time without being active, the operate time of the relay is slightly longer while the release time keeps mostly the same. Relay1 Voltage Contacts Operate Time (Mean / Mean Test 1) Relase Time (Mean / Mean Test 1) PANASONIC 5V 1 (CO) 5.7ms / 5.55ms 6.89ms / 7ms FINDER 5V 1 (NO) 5.57ms / 5.44ms 7.82ms / 7.97ms SCHRACK 5V 1 (CO) 4.77ms / 4.61ms 5.15ms / 5.2ms SCHRACK 5V 1 (NO) 5.56ms / 5.58ms 4.74ms / 4.78ms ELESTA RELAYS 12V 4 (3NO/1NC) 9.54ms / 9.41ms 7.61 ms / 7.6ms FINDER 12V 2 (CO) 11.63ms / 11.25ms 9.17 ms / 9.11ms DOLD 12V 6 (3NO/3NC) 17.32ms / 16.87ms 11.45 ms / 11.43ms PANASONIC 12V 8 (4NO/4NC) 15.07ms / 14.87ms 15.51ms / 15.59ms SCHRACK 12V 6 (3NO/3NC) 16.51ms / 15.66ms 7.01ms / 6.99ms FINDER 12V 1 (CO) 14.72ms / 14.75ms 12.68ms / 12.69ms SCHRACK 24V 4 (3NO/1NC) 10.25 ms / 9.72ms 11.56ms / 11.5ms HENGSTLER 24V 4 (2NO/1NC) 14.58ms / 14.4ms 12.26ms / 12.18ms OMROM 24V 6 (3NO/3NC) 12.69ms / 12.01ms 7.93 ms / 8ms HENGSTLER 24V 6 (4NO/2NC) 21.91ms / 21.78ms 18.64ms / 18.94ms TE-MPE-TM 3rd OCTOBER 2013 41 Results: Test 3 CERN TEST 3 [11] TE-MPE-TM 3rd OCTOBER 2013 42 CERN Results: Response Times Test 3 Operate Time ∙∙∙∙∙∙∙∙∙ Release Time- TE-MPE-TM 3rd OCTOBER 2013 43 Results: Response Times Test 3 CERN Following a day left in an energized state, the first release time of each relay was longer than the rest. Relay1 Voltage Contacts First Release Time Operate Time (Mean / Mean Test 1) Release Time (Mean / Mean Test 1) PANASONIC 5V 1 (CO) 7.54ms 5.61ms / 5.55ms 7.06ms / 7ms FINDER 5V 1 (NO) 8.96ms 5.46ms / 5.44ms 7.97ms / 7.97ms SCHRACK 5V 1 (CO) 5.55ms 4.64ms / 4.61ms 5.22ms / 5.2ms SCHRACK 5V 1 (NO) 5.19ms 5.55ms / 5.58ms 4.82ms / 4.78ms ELESTA RELAYS 12V 4 (3NO/1NC) 7.99ms 9.43ms / 9.41ms 7.66 ms / 7.6ms FINDER 12V 2 (CO) 9.58ms 11.29ms / 11.25ms 9.17 ms / 9.11ms DOLD 12V 6 (3NO/3NC) 12.02ms 16.84ms / 16.87ms 11.52 ms / 11.43ms PANASONIC 12V 8 (4NO/4NC) 15.83ms 14.97ms / 14.87ms 15.56ms / 15.59ms SCHRACK 12V 6 (3NO/3NC) 7.72ms 15.60ms / 15.66ms 7.23ms / 6.99ms FINDER 12V 1 (CO) 12.91ms 14.80ms / 14.75ms 12.63ms / 12.69ms SCHRACK 24V 4 (3NO/1NC) 11.95ms 10. 07 ms / 9.72ms 11.69ms / 11.5ms HENGSTLER 24V 4 (2NO/1NC) 12.78ms 14.4ms / 14.4ms 12.23ms / 12.18ms OMROM 24V 6 (3NO/3NC) 8.44ms 12.23ms / 12.01ms 7.93 ms / 8ms HENGSTLER 24V 6 (4NO/2NC) 19.54ms 21.80ms / 21.78ms 18.76ms / 18.94ms TE-MPE-TM 3rd OCTOBER 2013 44 Outline CERN Introduction to relays Scope of the study The test bench Results Conclusions [11] TE-MPE-TM 3rd OCTOBER 2013 45 Conclusions CERN The most important factor affecting relay reliability is the system in which the relay will be placed. The selection of the right dimensions, contact material, number of poles, switching capacity for inrush currents and other features is crucial for its performance and reliability. The most common relay failure is: failure to trip which should be taken into account when defining the safety system. There is a direct relation between the length of the contacts and the time response of the relay. Bouncing is more notable in relays with longer contacts. Relays from SCHRACK manufacturer had an excellent behaviour in terms of time response and bouncing. DOLD and PANASONIC safety relays showed the worst performance. The more contacts driven by the armature, the higher response time. No relay breakdown occurred even after exceeding the mechanical endurance specification. Relay dynamic response worsens with the number of operations. After a period of inactivity, the operate time is slightly longer. After being energized for a long period of time, the release time is longer. TE-MPE-TM 3rd OCTOBER 2013 46 End CERN THANKS FOR YOUR ATTENTION [11] TE-MPE-TM 3rd OCTOBER 2013 47