Power system protection

Types of tests in power system according to IEEE Std C37.233-2009: 1.Application certification type tests in the factory or laboratory: The objective of application certification type tests (also known as functional tests) is to verify the engineering design and performance of the system and its components through simulation of the full range of expected operating conditions. These cases can be in the form of playback of simulation results or realtime interactive testing. Typically, the developers run such type tests only on a first production sample if more than one is to be built. In the case of playback of simulated cases, the tests rely on power system or apparatus modeling, simulation, and tools to demonstrate the security and dependability of the scheme before shipping to the site. Features include comprehensive modeling of the application, standardized test cases, large variety of test cases to exercise design, and simulation of communications and environmental challenges of a field installation. The test personnel document the test cases and results in some detail. For a specialized protection system or critical application, representatives of the end user may witness some or all of the type testing process to learn the system and gain confidence. In general, component devices of a system under test have been or should be type-tested according to relevant standards for the physical and electrical environment. For example, protective relays are tested according to specified revisions of IEEE Std C37.90TM as well as IEEE Std C37.90.1TM, IEEE Std C37.90.2TM, and IEEE Std C37.90.3TM; such test results are documented separately. These welldefined product type tests are not discussed further in this document. 2. Commissioning tests (at installation site) : The objectives are to determine whether equipment was damaged or changed during shipping and field installation, to ensure that equipment is installed and wired properly, to verify that installers entered appropriate settings and option selections, and to observe interaction with the power apparatus. The test focus shifts from verification of design to verification that the system is working as designed. The commissioning test objectives are as follows: a)Install and integrate the system components with the site current transformers (CTs), voltage transformer (VTs), sensors, communications systems, wiring, and auxiliary power supplies. b)To verify that factory-supplied connections are correct and complete. c)To ensure each component performs in accordance with vendor specifications and type testing for that component. d)Test interactions, and overall system performance, with a sampling of test cases across the spectrum of possibilities but not a comprehensive suite as is used for factory type tests. e)Test the overall scheme by simulating power system events that cannot be generated on demand, using techniques described in this guide. Examples include transient simulation, tests for abnormal conditions, end-to-end testing, and functional testing of applications using IEC 61850. f)Operate other power apparatus or secondary control systems in the vicinity to show that the system is secure and/or dependable in the face of spurious environmental influences or communications traffic. g)Verify proper mapping and operation of the protective device with other data/control systems to which it is interconnected. 3.Periodic maintenance tests The objective is to detect in-service failures of components, wiring, interfaces, communications, or unwanted changes of setting or configuration. a)Assume the design requires no additional verification. b)Test for correctness of wiring or switching configuration that could conceivably have been changed by maintenance elsewhere in the substation, including polarity or phase rotation, and instrument transformer or other interface grounding/earthing.

Circuit breaker and contactor test 1. OBJECTIVE: To verify the physical condition and electrical characteristics of CB/ contactors. 2. TEST INSTRUMENTS REQUIRED: Insulation tester Micro ohmmeter CB timing test kit HV test kit 3. TEST PROCEDURE: 3.1. MECHANICAL CHECKS AND VISUAL INSPECTION: • Inspect for physical damage/ defects. • Check nameplate information for correctness. • Check tightness for all bolted connections. • Check the transport lock is removed for breaker/ contactor. • Check racking mechanism for alignment and smoothness operation. • Check operation of all mechanical interlocks. • Check correct breaker/contactor position indication. • Check for correct spring status indication. • For SF6 breakers check the correct gas pressure. • Check the manual operation of breaker/contactor. 3.2. INSULATION RESISTANCE TEST: The test voltage shall be between phase to earth and across the poles. - Each phase to earth (or body). - Across the pole for each phase. The applied test voltage limits shall be as per table 4.1. 10.3.3. CONTACT RESISTANCE TEST: This test is to confirm the resistance of the main contacts. Inject 100A DC current through the main contact by keeping CB closed. The voltage drop across the contact is measured and resistance is calculated. In many instruments resistance will be a direct reading. Limits: The obtained values shall be compared with factory test reports or manufacturer claimed values could be taken as reference. 3.4. CB TIMING TEST: This test is to verify the open and closing time of CB contacts. The test connection circuit is shown in Fig. Measure the closing time and tripping time with timing test kit that will measure and record the time and timing diagram. Limits: The obtained close/ open time shall be compared with manufacturer reference values or factory test results. 3.5. REDUCED VOLTAGE TEST: This test is to confirm the operation of closing coil and opening coil at reduced voltage applied. Apply reduce voltage of 80% of rated voltage for closing coil and 60% of rated voltage for trip coil and operation shall be noticed. Limits: Operation shall be observed without fail. 3.6. HIGH VOLTAGE TEST: This test shall be performed as per section of hight voltage test , i explained that before this publication. 3.7. APPLICABLE STANDARD: IEC 60056: High voltage AC circuit breakers.

Transformer protection 64R and mechanical protection of transformer as binary input , ABB relay REF542+

or b) below: a) Test for 5min with phase-to-phase voltage of the system applied between the conductor and the metallic screen b) Test for 24 hours with the normal operating voltage Uo of the system. Note: Normally cables have three voltages specified: i.e. Uo\U\Um Where Uo=rated Phase to earth/screen voltage U= rated Phase to phase voltage Um=rated maximum Phase to phase voltage -For cables used for solidly earthed system screen current for the earth fault will be high but cable Uo rating is low i.e. Uo=U/1.732 -For cables used for resistance earthed system screen current will be low for earth fault but cable Uo rating is high i.e. Uo=U Note: A VLF (Very Low Frequency) high voltage of 3xUo shall be applied between conductor and screen. Some utility customers are accepting this. 4. ACCEPTANCE LIMITS: For Switchgear: No flashover or disruptive discharge should occur during test. Corona discharge noise may be heard during this test. For Power cables: No flashover or disruptive discharge should occur during test. 5. APPLICABLE STANDARD: IEC 60298: - AC metal-enclosed switchgear and control gear for rated voltage above 1KV to 52KV. IEC 60694: - Common specifications for HV switchgear. IEC 60502: - Power cables with extruded insulation and their accessaries from 1KV up to 30KV.

Hight voltage test: 1. OBJECTIVE: To determine the equipment is in proper condition to put in service, after installation for which it was designed and to give some basis for predicting whether or not that a healthy condition will remain or if deterioration is underway which can result in abnormally short life. 2. TEST INSTRUMENTS REQUIRED: Calibrated AC hi-pot test set for switchgear with leakage current indicator and overload protection. Calibrated DC hi-pot test set for cables with leakage current indicator and overload protection. 3. TEST PROCEDURE: 3.1. SWITCHGEAR: It includes panel enclosure, bus bar, CT & breaker / contactor. The following precautions should be taken care, before starting the test: - A visual inspection will be made to ensure the surface dust and moisture has been removed from the component under test. - Ensure the component is isolated from other connected system, which may feed back to other components or circuits not under test. - A check shall be made to verify the ground for the component under test and test equipment being connected to system ground. - CT’s secondary terminals shall be shorted. - VT’s & Surge arresters shall be isolated from the equipment under test. - Mark out test area and assure nobody can enter during test. - Circuit breakers/contactors should be inserted and closed. - Busbars should be fully mounted tightened and shields between phases & between phases and earth should be in place. Moreover, busbar covers should be in place. - All earthing switches related to equipment under test should be open. - Busbar conductivity test shall be performed. - Insulation resistance test should be performed before and after commencing the test. - Instructions of test equipment being used should be followed. - After each test subject under test should be discharged to ground. - The test connection shall be made as shown in the fig. 5.1. Required test voltage shall be raised slowly and maintained for one minute between one phase and other phases connected to ground and than reduced slowly to zero, testing shall be repeated for other phases as mentioned above. During each test leakage current shall be recorded. After the above test, another test shall be repeated after opening all circuit breakers / contactors and applying test voltage across opening distance between poles with three poles shorted on both sides and grounded on one side only as shown in the fig.5.2. Test voltage limits are mentioned in table 5.1. 3.2. POWER CABLES: Following precautions shall be made before conducting test. - Cable under test should be clean and free of dust especially at insulators and stress cones. - Shields of all cables should be grounded and tied together at the near end of the cable and at far end bare conductor should be taped with some insulation. - Cable under test should be disconnected at both ends. This will assure that the cable under test will not feed back to circuits / components not under test. - Personnel should be stationed at both ends and / or the end opposite where the test is performed should be barricaded with warning tapes & signboards. - Instructions of test equipment being used should be followed. DC Voltage Test: Dc voltage shall be raised slowly up to 4 x Uo (rated power frequency voltage between conductor and earth or metallic screen) and maintained for 15 minutes between one phase and other phases and metallic screen of all phases connected with ground. After elapse of test time, voltage shall be reduced slowly to zero and the cable shall be discharged. Testing shall be repeated for other phases as mentioned above. Test voltage limits are mentioned in table 5.2 as per IEC 60502-2(1997-04): AC Voltage Test (Alternate method): As per IEC 60502-2(1997-04), as an alternate method after agreement between the contractor and purchaser, an a.c voltage may be applied as a)

Substation Overview . Transformers . Power Transmission . System Protection . Principles of System Operation

Siemens SWT 3000 Equipment Manual The interface module IFC is used for communication between protection equipment and the SWT 3000. The following versions are available: z Module IFC-D for Interface Command Direct tripping z Module IFC-P Normal version (Interface Command Permissive tripping) z Module IFC-S Signaling (Interface Command Signaling)

-Residual relay operates when either zero-sequence voltage or zero-sequence current are vector subtracted from each other either by direct measurement or by digital calculation with the resultant being above a preset value. -Time overcurrent relay operates when measured current is exceeded and operates with increasing speed according to a set function as the magnitude of current rises. -Undercurrent relay operates with a drop in measured current below a predetermined threshold. -Undervoltage relay operates with a drop in measured voltage below a predetermined threshold

Classification of Relays: Relays are classified in broad categories by methods of operation and by response characteristics. 1. Methods of Operation -Electromechanical relay operates electromechanically. -Gas Pressure relay responds to gas pressure. -Latching relay changes state and latches usually mechanically and then stays that way until changed again. -Percentage differential relay operates due to a difference in two currents with a linear increasein relay operation with a magnitude of through current. -Solid-state relay uses solid-state components to compare measured values to set replica values. -Digital relay uses digital means to compare algorithms and preset values to measured values. 2. Response Characteristics -Blinder relay measures impedance and is generally used to block another impedance relay fromtripping. -Definite time relay closes contacts after a definite time delay. -Differential relay measures the value of electrical quantities and closes contacts when the difference between them exceeds a specified amount. -Directional overcurrent relay measures current and closes contacts when the current exceeds apredetermined value and is in a predetermined direction with respect to a polarizing referencecurrent or voltage. -Directional power relay measures current and voltage and closes contacts when the two are in apredetermined phase relationship above a set threshold and is in one direction. -Directional relay operates when the voltage and current are in a phase relationship sufficient to cause relay operation for current in one direction. -Distance relay operates when measured impedance including magnitude and angle is above a setthreshold. -Frequency relay operates when the measured system frequency is either above or below a set threshold. -Ground relay is designed to measure either zero-sequence voltage or zero-sequence current. -Impedance relay operates when measured impedance in magnitude only is above a set threshold. -Inverse time relay operates when measured voltage or current is exceeded and operates with increasing speed according to a set function as the magnitude of either the voltage or current rises. -Lens relay is similar to a mho relay except that the characteristic is lens-shaped instead of circular to reduce the likelihood of operation under load. -Mho relay is an impedance relay that can be offset such that the center of the characteristic does not encompass the origin on a R-X plane. The angle of the circular characteristic’s diameter isadjustable with the angle known as the maximum torque angle (MTA) or relay characteristicangle (RCA). -Negative phase sequence relay operates when either negative sequence voltage or negative sequence current exceeds preset values which occur during unbalanced conditions. -Neutral relay is designed to measure either zero-sequence voltage or zero-sequence current wheneither by direct measurement or by digital calculation with the resultant being above a presetvalue. -Open phase relay responds to an open phase or phases. -Overcurrent relay measures current and closes contacts when the current exceeds a predetermined value due to a fault. -Overload relay measures current and closes contacts when the current exceeds a predetermined value due to an overload. -Overvoltage relay measures voltage and closes contacts when the voltage exceeds a predetermined value. -Phase comparison relay monitors the currents entering and leaving a given protection zone suchas a line and operates when the phase relationship between those currents exceeds a predetermined value. -Rate of change relay measures typically frequency but can be other electrical quantities and operates when the rate of change accelerates beyond a predetermined set value. -Reactance relay is an impedance relay with an impedance characteristic running in parallel withthe resistive axis and operates purely to a change of measured reactance regardless of impedanceangle.

Protections relay types from some company: 1. Distance : Siemens : (7SA522) ABB : (REL670) Areva : (P441,2,…) Toshiba : (GRZ100) 2. Current Differential : Siemens : (7SD61,7UT613) ABB : (REL551) AREVA : (P545) Reyroue : (Solkor, N) 3. Line Differential : Siemens : (7SD60,7SJ621,7UT613) ABB : (RED670,REL561) Toshiba : (GRL100) 4. Busbar protection high and low impedance: (Diff) Siemens : (7SS523) ABB : (REB500,RADHA(h) AREVA : (MCAG34(H) Reyrolle : (DAD) 5. Pilot Wire : AREVA : (HO4) Reyrolle : ( S01kor pf) 6. Transformer Bised differential: Siemens : (7UT613) Areva : P633,kBCH130,120,P631,P632) 7. Restricted earth fault high impedance: Siemens :(7vh600) ABB :(SPAE010) Areva : ( MCAG14 , MCAG34) 8. Over current and earth fault : Siemens : ( 7SJ61,7SJ602) Areva : (KCGG142,P123,P122) Toshiba : (GRD110) 9. Breaker Failure: Siemens : (7SS523,7VK61) ABB : ( RAICA,SEL352) 10.under/ over voltage : AREVA:( P921) Toshiba : (GRD130) 11.Directional over current : Siemens :(7SJ62) AREVA: (KCEG142) 12.Transformer standby earth fault Siemens : (7SJ602, 7SJ610, 7SJ612) 13.Thermal over load : Siemens :(7SJ612, 7SJ511) AREVA : (P123) 14.Auto reclose and synchro chek : Siemens :(7VK511,LFA102) AREVA: (KAVR130) Toshiba :(GR100) 15.Auto reclose: Siemens :(7VK512) ABB: (REXA101,REXA103) 16.Manual synchro cheek : Siemens :(7VK611) AREVA: KAVS100

Leading Causes of Lockout/Tagout Injuries : The leading causes of injury are: • Failure to shut off equipment • Failure to disconnect from power source • Unexpected restarting of equipment • Failure to clear work area before restarting .

What is Lockout/Tagout? Lockout/Tagout is the procedure for a safe shut down and restart of equipment that is serviced, maintained or cleaned. Lockout protects employees who service and maintain equipment and also protects the employees who clean the area by the placement of a lock on a device that will prevent energy from reaching the machine that is being serviced or maintained. • The lock ensures that the equipment cannot be turned on while the work is occurring. • Tagout warns employees of the shutdown by the placement of a tag on the energy isolating device which warns others that you are working on the equipment and it must not be started.