Alstom 14x feeder protection testing procedure

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Information about Alstom 14x feeder protection testing procedure

Published on October 16, 2016

Author: davidroy39

Source: slideshare.net

1. TESTING PROCEDURE FOR 14x ALSTOM MAKE RELAYS 1. Objective: Testing procedure and explanation for the main functions of the P14x relay using a Test kit. 2. Requirements for Testing: Ø Three Phase relay test kit. Ø Multimeter. Ø Wires for Shorting. Ø Scheme Drawings. 3. Current and Voltage details: Rated Current: 1A / 5A Rated Voltage: 110 V AC Rated Auxiliary supply: 220 V DC 4. Measurement Check: Ø Current Injection: Use suitable three phase current injection kit for injecting current for all three phases. TB reference for current injection for the relay as per the scheme drawing: Connect the current A, B, C phase & Neutral test leads from the Test kit to the TB references mentioned above for testing. Ensure that there is no open circuit before starting injection of current to the relay. Inject rated current of 1A in all three phases with correct phase sequence and note the measured currents for all three phases.

2. Ø Voltage Injection: The three phase voltage from the kit should be applied across the voltage input terminals of the relay. TB reference for Voltage injection for the relay as per the scheme drawing: Connect the voltage test leads of A, B & C phase along with Neutral from the Testing Kit to the above mentioned TBs for voltage injection. Apply rated voltage of 110V across all the three phases with correct phase sequence and note the measured voltage for all three phases. Ø Configured Protection: 1. Phase Over Current Protection 2. Earth Fault Protection. 3. REF Protection. 4. Standby Earth fault protection. 5. Local Breaker Backup protection (CB Fail). 1. Phase Over Current Protection The over current protection included in the P14x relay provides four-stage non-directional/directional three-phase over current protection with independent time delay characteristics. All over current and directional settings apply to all three phases but are independent for each of the four stages. The first two stages of over current protection have time-delayed characteristics which are selectable between inverse definite minimum time (IDMT) and definite time (DT). The third and fourth stages have definite time characteristics only.

3. Various methods are available to achieve correct relay co-ordination on a system; by means of time alone, current alone or a combination of both time and current. Grading by means of current is only possible where there is an appreciable difference in fault level between the two relay locations. Grading by time is used by some utilities but can often lead to excessive fault clearance times at or near source substations where the fault level is highest. For these reasons the most commonly applied characteristic in coordinating over current relays is the IDMT type. Ø Stage 1: a. Pick up Check This test is required to find the pickup value of over current protection. For carrying out this check the following settings are done in the relay. Now inject current in all three phase and raise current in A phase till the relay operates and note down the reading below. Repeat this for other two phases and record the reading. b. Timing Check: This test is required to find the operating time for over current protection. For carrying out this check, the following settings are done in the relay. Inverse Definite Minimum Time:

4. Now inject current in AN Phase equal to 2 times of I>1 setting and check for the operating time and record it. Repeat this for 4 times, 6 times & 8 times of the I>1 setting and record the operating times in the below format. Repeat this for BN & CN Phases also. Ø Stage 2: a. Pick up Check This test is required to find the pickup value of over current protection. For carrying out this check the following settings are done in the relay. Now inject rated current in all three phases and raise current in A phase till the relay operates and note down the reading below. Repeat this for other two phases and record the reading. b. Timing Check: Definite Time:

5. Now inject current in AN phase equal to 2 times of I>2 setting and record the actual operating time. Repeat the same for the remaining B phase and C phase. 2. Earth Fault Protection: The P141 relay have a total of five input current transformers; one for each of the phase current inputs and two for supplying the earth fault protection elements. With this flexible input arrangement, various combinations of standard, sensitive (SEF) and restricted earth fault (REF) protection may be configured within the relay. It should be noted that in order to achieve the sensitive setting range that is available in the P14x relays for SEF protection, the input CT is designed specifically to operate at low current magnitudes. This input is common to both the SEF and high impedance REF protection, so these features are treated as mutually exclusive within the relay menu. The standard earth fault protection elements are duplicated within the P141 relays and are referred to in the relay menu as “Earth Fault 1” (EF1) and “Earth Fault 2” (EF2). EF1 operates from earth fault current which is measured directly from the system; either by means of a separate CT located in a power system earth connection or via a residual connection of the three line CTs. The EF2 element operates from a residual current quantity which is derived internally from the summation of the three-phase currents. EF1 and EF2 are identical elements, each having four stages. The first and second stages have selectable IDMT or DT characteristics, while the third and fourth stages are DT only. Each stage is selectable to be either non-directional, directional forward or directional reverse. The Timer Hold facility is available on each of the first two stages. Ø Stage 1: a. Pick up Check If the Earth fault is achieved as derived from 3 phase CTs then “Earth fault 2” shall be configured and in case if the earth fault is achieved from a dedicated neutral CT then “Earth fault 1” function shall be configured. This test is required to find the pickup value of earth fault protection. For carrying out this check the following settings are done in the relay. Now inject rated current in all three phase and raise current in A phase till the relay operates and note down the reading below. Repeat this for other two phases and record the reading.

6. b. Timing Check: This test is required to find the operating time for earth fault protection. For carrying out this check, the following settings are done in the relay. Inverse Definite Minimum Time: Now inject current in AN Phase equal to 2 times of IN2>1 setting and check for the operating time and record it. Repeat this for 4 times, 6 times & 8 times of the IN2>1 setting and record the operating times in the below format. Repeat this for BN & CN Phases also. Ø Stage 2: a. Pick up Check This test is required to find the pickup value of earth fault protection. For carrying out this check the following settings are done in the relay.

7. Now inject a current which is less then the setting in all three phase and raise current in A phase till the relay operates and note down the reading below. Repeat this for other two phases and record the reading. b. Timing Check: Definite Time: Now inject current in AN phase equal to 2 times of IN>2 setting and record the actual operating time. Repeat the same for the remaining B phase and C phase. 3. REF Protection: The REF protection in the P141 relays may be configured to operate as either a high impedance or low impedance element. The high impedance REF element of the relay shares the same CT input as the SEF protection hence, only one of these elements may be selected. However, the low impedance REF element does not use the SEF input and so may be selected at the same time. In this project the REF protection is of High Impedance REF.

8. a. Pick up Check This test is required to find the pickup value of restricted earth fault protection. For carrying out this check the following settings are done in the relay. Before starting the testing short the Stabilizing resistor terminals. Now start injecting current less than the pickup value (or start from 0) and raise the current till the relay operates. Record this value in the below format. 4. CB Fail Protection: The circuit breaker failure protection incorporates two timers, "CB Fail 1 Timer" and "CB Fail 2 Timer", allowing configuration for the following Simple CBF, where only "CB Fail 1 Timer" is enabled. For any protection trip, the "CB Fail 1 Timer" is started, and normally reset when the circuit breaker opens to isolate the fault. If breaker opening is not detected, "CB Fail 1 Timer" times out and closes an output contact assigned to breaker fail (using the programmable scheme logic). This contact is used to back trip upstream switchgear, generally tripping all in feeds connected to the same bus bar section A re-tripping scheme, plus delayed back tripping. Here, "CB Fail 1 Timer" is used to route a trip to a second trip circuit of the same circuit breaker. This requires duplicated circuit breaker trip coils, and is known as re-tripping. Should re-tripping fail to open the circuit breaker, a back trip may be issued following an additional time delay. The back trip uses "CB Fail 2 Timer", which is also started at the instant of the initial protection element trip. a. CB Fail 1

9. CB Fail 1 Pick up checks: Before starting the test ensure that the Opto Inputs assigned for phase segregated signals “External A ph trip”, “External B ph trip” & “External C ph trip” when current is injected in the respective phases or a common signal for 3 phases “External 3 Ph trip” shall be energized during this test. For the pickup checks make the timer setting to 0 sec. Now inject current in AN terminals less than the pickup setting and ensure that the Opto “External A ph trip” or “External 3 ph trip” is energized during the current injection, and slowly raise the current till the relay operates. Record the pick up value and repeat this test for BN & CN phases also energizing the respective optos. CB Fail 1 Timing pick up checks: Before starting this test ensure that the timer value is set in the relay settings as per the requirement and also the respective Opto inputs are also high during the testing. Now inject current in AN phase terminals equal to or more than 2 times of CB fail pickup setting for finding the operating time. After injection of the current wait the relay operates and record the time. Repeat for BN & CN Phases also and record the operating time. 5. Standby Earth Fault Protection The standby earth fault protection elements are duplicated within the P141 relays and are referred to in the relay menu as “Earth Fault 1” (EF1) and “Earth Fault 2” (EF2). EF1 operates from earth fault current which is measured directly from the system; either by means of a separate CT located in a power system earth connection or via a residual connection of the three line CTs.

10. a. Pick up Check This test is required to find the pickup value of Standby Earth fault protection. For carrying out this check the following settings are done in the relay. For pickup checks the time delay shall be set as 0 sec. Now inject current less than the relay pickup setting in the Neutral CT input terminals and slowly increase the current till the relay operates and record the value. b. Timing Check: This test is required to find the operating time for standby earth fault protection. For carrying out this check, the following settings are done in the relay. Definite Time: Now inject current of 2 times of IN1>1 in the respective terminals and wait till the relay operates and record the operating time.

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