Slave Relay Testing

Question 1

What is the purpose of the Engineered Safeguards Actuation System?

Answer 1

Initiates action to protect the core and Reactor Coolant System components, and to ensure containment integrity in the event of an accident.

Question 2

What is the generic flow path of through the system form signal generation to slave relay actuation?

Answer 2

Instrument –> bistable –> logic bay –> output bay –> master relay –> slave relay –>component actuation

Question 3

Where are Slave Relays tested?

Answer 3

The slave relays are tested inside the Safeguards Test Cabinet

Question 4

What is contained inside of the Safeguards Test Cabinet?

Answer 4

1. Test switches and indicating lamps
2. Rotary test relays
3. Electronic components associated with the test circuitry

Question 5

What are the two types of Slave Relay testing?

Answer 5

1. Go Testing

2. Block Testing

Question 6

What is Go Testing in relation to Slave Relay testing?

Answer 6

Go testing energizes the slave relay and actuates protective a protective device such as a pump, valve, or fan.

Question 7

What is Block Testing in relation to Slave Relay testing?

Answer 7

Block testing energizes the slave relay and checks continuity of the control circuit instead of operating the final actuation device.

Question 8

What are the three types of Slave Relays?

Answer 8

1. Potter & Brumfield MDR-66-4 rotary type relay
2. Westinghouse Industrial Control Slave Relays
   A. Non-latching relays
   B. Latching relays
3. Cutler-Hammer latching relay

Question 9

How can you tell if a Potter & Brumfield rotary type relay is unlatched/unblocked?

Answer 9

The line in the indicator plug is aligned with the lines on the relay face.

Question 10

How can you tell if a Potter & Brumfield rotary type relay is latched/blocked?

Answer 10

The line in the indicator plug is misaligned by approximately 30 degrees from the lines on the relay face.

Question 11

How can you tell if a Westinghouse Industrial Control Slave Relay(non-latching) is energized?

Answer 11

The bar on the relay face is depressed

Question 12

How can you tell if a Westinghouse Industrial Control Slave Relay(non-latching) is de-energized?

Answer 12

The bar on the relay face is flush with the relay face

Question 13

How can you tell if a Westinghouse Industrial Control Slave Relay(latching) is de-energized/unlatched?

Answer 13

The plunger indicator is protruding from the relay face

Question 14

How can you tell if a Westinghouse Industrial Control Slave Relay(latching) is energized/latched?

Answer 14

The plunger is flush with the relay face(depressed)

Question 15

How can a Westinghouse Industrial Control Slave Relay(latching) be manually energized?

Answer 15

The relays can be manually energized by depressing the plunger

Question 16

How can you tell if a Culter-Hammer latching relay is de-energized/unlatched?

Answer 16

The plunger is flush with the relay face

Question 17

How can you tell if a Culter-Hammer latching relay is energized/latched?

Answer 17

The plunger is protrudes from the relay, and you can usually see red on the plunger

Question 18

What are some of the typical failure modes of relays?

Answer 18

1. Failure to latch
2. Failure to reset
3. Contact resistance to high
4. Components fail to position

Question 19

What are some indications that a relay has failed to latch?

Answer 19

1. Components do not position properly or test lamps not staying in correct state when the test switch is released after being depressed
2. Notify the test coordinator to see if the relay has latched
3. Contact Engineering prior to proceeding with the test

Question 20

What are some indications that a relay has failed to reset?

Answer 20

1. Components do not return to their “as found” positions
2. Check to see if the relay is still in a latched state
3. Contact Engineering prior to proceeding with the test

Question 21

What can cause a relay’s resistance to be too high?

Answer 21

Usually due to oxidation of the connections to the slave relay

Question 22

What should your action be if components fail to position?

Answer 22

1. Check to see if the relay is latched
2. Contact Engineering prior to proceeding with the test to determine if “evidence” of the failure will be destroyed by resetting