Breakers, Relays, and Disconnects

Question 1

To completely deenergize an electrical component and its associated control and indication circuits,
the component breaker should be…

A. open with the control switch in Pull-To-Lock.

B. open with the control switch tagged in the open position.

C. racked out and tagged in the racked-out position.

D. racked out with control power fuses removed.

Answer 1

racked out with control power fuses removed.

Question 2

Which one of the following describes the normal operation of a local breaker overcurrent trip flag
indicator?

A. Actuates when no lockout is present; satisfies an electrical interlock to remotely close a breaker.

B. Actuates when a breaker overcurrent trip has occurred; can be manually reset when the overcurrent
condition clears.

C. Actuates when a breaker has failed to trip on an overcurrent condition; can be manually reset when
the overcurrent condition clears.

D. Actuates to cause a breaker trip when the overcurrent trip setpoint is reached; can be remotely reset
when the overcurrent condition clears.

Answer 2

Actuates when a breaker overcurrent trip has occurred; can be manually reset when the overcurrent
condition clears.

Question 3

Which one of the following describes the local overcurrent trip flag indicators for a breaker?

A. They actuate prior to breaker tripping to warn of imminent protective action.

B. They indicate breaker overcurrent trip actuation during and after breaker trip actuation.

C. When actuated, they indicate that the associated breaker has failed to trip open.

D. When actuated, they indicate that the breaker overcurrent trip relay has been reset.

Answer 3

They indicate breaker overcurrent trip actuation during and after breaker trip actuation.

Question 4

Loss of breaker control power will cause…

A. breaker line voltage to indicate zero regardless of actual breaker position.

B. the remote breaker position to indicate open regardless of actual breaker position.

C. inability to operate the breaker locally and remotely.

D. failure of the closing spring to charge following local closing of the breaker.

Answer 4

failure of the closing spring to charge following local closing of the breaker.

Question 5

Which one of the following will result from a loss of control power to a motor supply breaker?

A. The motor ammeter indication will be zero regardless of actual breaker position.

B. The breaker position will remotely indicate closed regardless of actual position.

C. The breaker will trip open due to the actuation of its protective trip device.

D. The charging motor will not recharge the closing spring after the breaker closes.

Answer 5

The charging motor will not recharge the closing spring after the breaker closes.

Question 6

Which one of the following will cause a loss of ability to remotely open a breaker and a loss of remote
breaker position indication?

A. Failure of the breaker control switch.

B. Racking the breaker to the TEST position.

C. Mechanical binding of the breaker tripping bar.

D. Loss of control power for the breaker.

Answer 6

Loss of control power for the breaker.

Question 7

Which one of the following will cause a loss of indication from the remote breaker position indicating
lights associated with a typical 480 VAC load supply breaker?

A. Locally opening the breaker.

B. Loss of breaker line voltage.

C. Removing the breaker control power fuses.

D. Burnout of the local breaker position indicating lights.

Answer 7

Removing the breaker control power fuses.

Question 8

How is typical breaker operation affected when the associated breaker control power transfer switch is
placed in the LOCAL position?

A. Control power will be available to provide protective trips, and the breaker can be electrically
operated only from the control room.

B. Control power will be removed from both the open and close circuits, and the breaker can be
electrically operated only from the control room.

C. Control power will be available to provide protective trips, and the breaker can be electrically
operated only from the breaker cabinet.

D. Control power will be removed from both the open and close circuits, and the breaker can be
electrically operated only from the breaker cabinet.

Answer 8

Control power will be available to provide protective trips, and the breaker can be electrically
operated only from the breaker cabinet.

Question 9

A typical 120 VAC manual circuit breaker tripped due to overload. To close this circuit breaker, the
handle must be moved from the…

A. OFF position directly to the ON position; trip latch reset is not required.

B. midposition directly to the ON position; trip latch reset is not required.

C. OFF position to the midposition to reset the trip latch, and then to the ON position.

D. midposition to the OFF position to reset the trip latch, and then to the ON position.

Answer 9

midposition to the OFF position to reset the trip latch, and then to the ON position.

Question 10

Two identical 1,000 MW generators are operating in parallel, supplying the same isolated electrical
bus. The generator output breakers provide identical protection for the generators. Generator A and
B output indications are as follows:
Generator A Generator B
22.5 KV 22.5 KV
60.2 Hertz 60.2 Hertz
750 MW 750 MW
25 MVAR (out) 50 MVAR (out)
A malfunction causes the voltage regulator setpoint for generator B to slowly and continuously
increase. If no operator action is taken, which one of the following describes the electrical current
indications for generator A?

A. Current will decrease continuously until the output breaker for generator A trips on reverse power.

B. Current will decrease continuously until the output breaker for generator B trips on reverse power.

C. Current will initially decrease, and then increase until the output breaker for generator A trips on
overcurrent.

D. Current will initially decrease, and then increase until the output breaker for generator B trips on
overcurrent.

Answer 10

Current will initially decrease, and then increase until the output breaker for generator B trips on
overcurrent.

Question 11

Two identical 1,000 MW generators are operating in parallel, supplying all the loads on an isolated
electrical bus. The generator output breakers provide identical protection for the generators.
Generator A and B output indications are as follows:
Generator A Generator B
28 KV 28 KV
60 Hertz 60 Hertz
150 MW 100 MW
25 MVAR (out) 50 MVAR (out)
A malfunction causes the voltage regulator setpoint for generator B to slowly and continuously
decrease. If no operator action is taken, the electrical current indication for generator B will…

A. initially decrease, and then increase until the output breaker for generator A trips on overcurrent.

B. initially decrease, and then increase until the output breaker for generator B trips on overcurrent.

C. decrease continuously until the output breaker for generator A trips on overcurrent.

D. decrease continuously until the output breaker for generator B trips on reverse power.

Answer 11

initially decrease, and then increase until the output breaker for generator A trips on overcurrent.

Question 12

Two identical 1,000 MW generators are operating in parallel supplying the same isolated electrical
bus. The generator output breakers also provide identical protection for the generators. Generator A
and B output indications are as follows:
Generator A Generator B
22 KV 22 KV
60.2 Hertz 60.2 Hertz
200 MW 200 MW
25 MVAR (out) 50 MVAR (out)
A malfunction causes the voltage regulator setpoint for generator A to slowly and continuously
increase. If no operator action is taken, generator B output current will…

A. initially decrease, and then increase until the output breaker for generator A trips on overcurrent.

B. initially decrease, and then increase until the output breaker for generator B trips on overcurrent.

C. increase continuously until the output breaker for generator A trips on overcurrent.

D. increase continuously until the output breaker for generator B trips on overcurrent.

Answer 12

initially decrease, and then increase until the output breaker for generator A trips on overcurrent.

Question 13

Two identical 1,000 MW electrical generators are operating in parallel supplying the same isolated
electrical bus. The generator output breakers provide identical protection for the generators.
Generator A and B output indications are as follows:
Generator A Generator B
22 KV 22 KV
60.2 Hertz 60.2 Hertz
200 MW 200 MW
25 MVAR (out) 50 MVAR (out)
A malfunction causes the voltage regulator setpoint for generator A to slowly and continuously
decrease. If no operator action is taken, generator B output current will increase until…

A. the output breaker for generator A trips on overcurrent.

B. the output breaker for generator B trips on overcurrent.

C. the output breaker for generator A trips on reverse power.

D. the output breaker for generator B trips on reverse power.

Answer 13

the output breaker for generator B trips on overcurrent.

Question 14

Two identical 1,000 MW generators are operating in parallel supplying the same isolated electrical
bus. The generator output breakers provide identical protection for the generators. Generator A and
B output indications are as follows:
Generator A Generator B
22 KV 22 KV
60.2 Hertz 60.2 Hertz
200 MW 200 MW
25 MVAR (out) 50 MVAR (out)
A malfunction causes the voltage regulator setpoint for generator B to slowly and continuously
increase. If no operator action is taken, generator A output current will…

A. increase continuously until the output breaker for generator A trips on overcurrent.

B. decrease continuously until the output breaker for generator B trips on overcurrent.

C. initially decrease, and then increase until the output breaker for generator A trips on overcurrent.

D. initially decrease, and then increase until the output breaker for generator B trips on overcurrent.

Answer 14

initially decrease, and then increase until the output breaker for generator B trips on overcurrent.

Question 15

Refer to the drawing of a valve motor control circuit (see figure below).
What is the purpose of depressing the S1 pushbutton?

A. To deenergize the K3 relay after the initiating condition has cleared.

B. To prevent energizing the K3 relay when the initiating condition occurs.

C. To manually energize the K3 relay in the absence of the initiating condition.

D. To maintain the K3 relay energized after the initiating condition has cleared.

Answer 15

To deenergize the K3 relay after the initiating condition has cleared.

Question 16

Refer to the drawing of a valve motor control circuit (see figure below).
One purpose of the K3 relay is to…

A. hold the valve open after one or both initiating conditions have cleared, even if the reset
pushbutton (S1) is depressed.

B. hold the valve open even if one or both initiating conditions have cleared.

C. close the valve as soon as either initiating condition has cleared.

D. close the valve as soon as both initiating conditions have cleared.

Answer 16

hold the valve open even if one or both initiating conditions have cleared.

Question 17

Refer to the drawing of a valve motor control circuit (see figure below).
The valve is currently open with the contact configuration as shown. If the S1 pushbutton is
depressed, the valve will __________; and when the S1 pushbutton is subsequently released, the valve
will __________.

A. remain open; remain open

B. close; remain closed

C. remain open; close

D. close; open

Answer 17

close; remain closed

Question 18

Refer to the drawing of a valve motor control circuit (see figure below).
Which one of the following describes the function of the #3 contact?

A. To keep the K3 relay energized after the initiating condition clears.

B. To provide a method for manually energizing the K3 relay.

C. To increase circuit reliability because any one of the three contacts can energize the K3 relay.

D. To ensure the K3 relay can always be deenergized even with the initiating condition present.

Answer 18

To keep the K3 relay energized after the initiating condition clears.

Question 19

Refer to the drawing of a valve motor control circuit (see figure below).
The initiating condition occurs and closes the #1 and #2 contacts to energize the K3 relay and open the
valve. Which one of the following will close the valve?

A. Loss of 125 VDC.

B. Both #1 and #2 contacts open.

C. Either #1 or #2 contact opens.

D. Depressing the S1 pushbutton with the initiating condition present.

Answer 19

Loss of 125 VDC.

Question 20

Refer to the drawing of a valve motor control circuit (see figure below).
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
If the valve is currently closed, when will the alarm actuate?

A. As soon as PB2 is pushed.

B. Ten seconds after PB2 is pushed if the valve is still closed.

C. Immediately upon pushing PB2 and for the next 10 seconds if the valve remains closed.

D. Ten seconds after PB2 is pushed if the valve is still stroking open.

Answer 20

Ten seconds after PB2 is pushed if the valve is still closed.

Question 21

Refer to the drawing of a valve motor control circuit for a valve that is currently fully closed (see
figure below).
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
Which one of the following describes when the motor-operated valve will begin to stroke open?

A. At the same time the alarm actuates.

B. 10 seconds after PB2 is depressed.

C. Immediately after PB2 is depressed.

D. Immediately after PB1 is depressed if contact #1 is closed.

Answer 21

Immediately after PB2 is depressed.

Question 22

Refer to the drawing of a valve motor control circuit (see figure below).
Pushbutton PB2 was depressed to open the valve, and the current contact and pushbutton status is as
shown with the following exceptions:
LS1 is closed.
LS3 is closed.
#1 contact is closed.
#2 contact is closed.
Which one of the following describes the condition of the valve and its control circuit?

A. The valve is closed and the valve motor circuit has just been energized to open the valve.

B. The valve is closed and an open demand signal has existed for at least 10 seconds.

C. The valve is partially open and the valve motor circuit is deenergized because PB2 was
prematurely released.

D. The valve is partially open and an open demand signal has existed for at least 10 seconds.

Answer 22

The valve is closed and an open demand signal has existed for at least 10 seconds.

Question 23

Refer to the drawing of a valve motor control circuit (see figure below).
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
Which one of the following describes the purpose of the alarm?

A. Alert the operator when the valve motor circuit has been energized for 10 seconds after pushbutton
PB2 is depressed.

B. Alert the operator when the valve has not moved off its closed seat within 10 seconds of depressing
pushbutton PB2.

C. Alert the operator that the valve is opening by sounding the alarm for 10 seconds after PB2 is
depressed.

D. Alert the operator if the valve has not reached full open within 10 seconds of depressing
pushbutton PB2.

Answer 23

Alert the operator when the valve has not moved off its closed seat within 10 seconds of depressing
pushbutton PB2.

Question 24

Refer to the drawing of a valve motor control circuit (see figure below).
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
The valve is half open and moving to the open position. Which one of the following describes the
current condition of the valve position indicating lights?

A. Red light on, green light on

B. Red light on, green light off

C. Red light off, green light on

D. Red light off, green light off

Answer 24

Red light on, green light on

Question 25

Refer to the drawing of a valve motor control circuit (see figure below).
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
Pushbutton PB2 has been momentarily depressed and then released, and the valve is currently at
mid-stroke and moving to the open position. Under these conditions, which one of the following
describes the position of contacts #1, #2, and #3?

A. #1 closed; #2 open; #3 open

B. #1 open; #2 closed; #3 closed

C. #1 open; #2 closed; #3 open

D. #1 closed; #2 open; #3 closed

Answer 25

1 closed; #2 open; #3 open

Question 26

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully open and has a 10-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
Which one of the following describes the valve response if the control switch is taken to the CLOSE
position for two seconds and then released?

A. The valve will not move.

B. The valve will close fully.

C. The valve will begin to close and then stop moving.

D. The valve will begin to close and then open fully.

Answer 26

The valve will begin to close and then stop moving.

Question 27

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully closed and has a 10-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
Which one of the following describes the valve response if the control switch is taken to the OPEN
position for two seconds and then released?

A. The valve will not move.

B. The valve will open fully.

C. The valve will begin to open and then stop moving.

D. The valve will begin to open and then close fully.

Answer 27

The valve will open fully.

Question 28

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully open and has a 10-second stroke time. Limit switch LS2 has failed open.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
Which one of the following describes the valve response if the control switch is taken to the CLOSE
position for 2 seconds and then released?

A. The valve will not move.

B. The valve will close fully.

C. The valve will begin to close and then stop moving.

D. The valve will begin to close and then open fully.

Answer 28

The valve will not move.

Question 29

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully closed and has a 10-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
The operator takes the control switch to OPEN momentarily and the valve begins to open. Five
seconds later, the operator takes the switch to CLOSE momentarily and then releases the switch.
Which one of the following describes the valve response after the switch is released?

A. The valve will stop opening and remain partially open.

B. The valve will stop opening and then go fully closed.

C. The valve will open fully and remain fully open.

D. The valve will open fully and then go fully closed.

Answer 29

The valve will open fully and remain fully open.

Question 30

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully closed and has a 10-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
An operator takes the control switch to OPEN momentarily and the valve begins to open. Five
seconds later, the operator places and holds the switch in the CLOSE position. Which one of the
following describes the valve response with the switch held in the CLOSE position?

A. The valve will stop opening and remain partially open.

B. The valve will stop opening and then go fully closed.

C. The valve will open fully and remain fully open.

D. The valve will open fully and then go fully closed.

Answer 30

The valve will open fully and then go fully closed.

Question 31

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully closed and has a 10-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
An operator takes the control switch to OPEN. Two seconds later, after verifying the valve is
opening, the operator releases the control switch. Which one of the following describes the valve
motor control circuit alarm response after the switch is released?

A. The alarm will continue to actuate for approximately 8 seconds.

B. The alarm will continue to actuate until additional operator action is taken.

C. The alarm will actuate after approximately 8 seconds.

D. The alarm will not actuate until additional operator action is taken.

Answer 31

The alarm will continue to actuate for approximately 8 seconds.

Question 32

Refer to the drawing of a motor and its control circuit (see figure below).
Note: Relay contacts are shown open/closed according to the standard convention for control circuit
drawings.
What is the purpose of the Time Delay Coil (TD) in the motor controller circuit?

A. Ensures the motor cannot be started until the overload relays are reset.

B. Ensures the motor cannot be started until the accelerating coil is energized.

C. Allows the motor to come up to speed before bypassing the starting resistors.

D. Allows the motor to come up to speed before placing the starting resistors in the circuit.

Answer 32

Allows the motor to come up to speed before bypassing the starting resistors.

Question 33

Refer to the drawing of a motor and its control circuit (see figure below).
Note: Relay contacts are shown open/closed according to the standard convention for control circuit
drawings.
The motor receives overload protection from __________ overload relays; and __________ overload
relay(s) must actuate to deenergize the motor.

A. two; one

B. two; two

C. three; one

D. three; two

Answer 33

two; one

Question 34

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully closed and has a 10-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
The operator takes the control switch to OPEN for 5 seconds and then releases the switch. After one
minute, the operator takes the control switch to CLOSE for 5 seconds and then releases the switch.
Which one of the following describes the valve position immediately after the control switch is
released the second time?

A. Approximately fully open.

B. Approximately fully closed.

C. Approximately 50 percent open.

D. Cannot be determined without additional information.

Answer 34

Approximately fully closed.

Question 35

Refer to the drawing of a motor and its control circuit (see figure below).
Note: Relay contacts are shown open/closed according to the standard convention for control circuit
drawings.
How are the starting resistors employed before and after the motor is energized?

A. Inserted before the motor is energized; simultaneously bypassed after the motor gains speed.

B. Inserted before the motor is energized; sequentially bypassed as the motor gains speed.

C. Bypassed before the motor is energized; simultaneously inserted after the motor gains speed.

D. Bypassed before the motor is energized; sequentially inserted as the motor gains speed.

Answer 35

Inserted before the motor is energized; simultaneously bypassed after the motor gains speed.

Question 36

Refer to the drawing of a motor and its control circuit (see figure below).
Note: Relay contacts are shown open/closed according to the standard convention for control circuit
drawings.
The motor has been operating for several hours when it is decided to stop the motor. What is the
status of the starting resistors before and after the motor STOP pushbutton is depressed?

A. Initially inserted in the motor circuit; bypassed immediately after the STOP pushbutton is
depressed.

B. Initially inserted in the motor circuit; bypassed following a preset time delay after the STOP
pushbutton is depressed.

C. Initially bypassed; bypass is removed immediately after the STOP pushbutton is depressed.

D. Initially bypassed; bypass is removed following a preset time delay after the STOP pushbutton is
depressed.

Answer 36

Initially bypassed; bypass is removed immediately after the STOP pushbutton is depressed.

Question 37

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully closed and has a 10-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
Which one of the following describes the valve response if the control switch is taken to the OPEN
position for two seconds and then released?

A. The valve will not move.

B. The valve will open fully.

C. The valve will begin to open and then stop moving.

D. The valve will begin to open and then close fully.

Answer 37

The valve will begin to open and then stop moving.

Question 38

Refer to the drawing of a motor and its control circuit (see figure below).
Note: Relay contacts are shown open/closed according to the standard convention for control circuit
drawings.
The motor has been idle for several days when it is decided to start the motor. What is the status of
the starting resistors before and after the motor START pushbutton is depressed?

A. Initially bypassed; bypass is removed immediately after the START pushbutton is depressed.

B. Initially bypassed; bypass is removed following a preset time delay after the START pushbutton is
depressed.

C. Initially inserted in the motor circuit; bypassed immediately after the START pushbutton is
depressed.

D. Initially inserted in the motor circuit; bypassed following a preset time delay after the START
pushbutton is depressed.

Answer 38

Initially inserted in the motor circuit; bypassed following a preset time delay after the START
pushbutton is depressed.

Question 39

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully open and has a 10-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
The operator takes the control switch to CLOSE. Two seconds later, after verifying the valve is
closing, the operator releases the control switch. Which one of the following describes the valve
motor control circuit alarm response after the switch is released?

A. The alarm will continue to actuate for approximately 8 seconds.

B. The alarm will continue to actuate until additional operator action is taken.

C. The alarm will actuate after approximately 8 seconds.

D. The alarm will not actuate until additional operator action is taken.

Answer 39

The alarm will continue to actuate until additional operator action is taken.

Question 40

Refer to the drawing of a valve motor control circuit (see figure below).
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
Which one of the following will actuate the alarm?

A. With the valve partially closed, the control switch is taken to the CLOSE position.

B. With the valve partially closed, the control switch is taken to the OPEN position.

C. With the valve fully open, the control switch is taken to the CLOSE position.

D. With the valve fully open, the control switch is taken to the OPEN position.

Answer 40

With the valve partially closed, the control switch is taken to the OPEN position.

Question 41

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully open and has a 10-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
The operator takes the control switch to CLOSE momentarily and the valve begins to close. Five
seconds later, the operator takes the switch to OPEN momentarily and then releases the switch.
Which one of the following describes the valve response after the switch is released?

A. The valve will stop closing and remain partially open.

B. The valve will stop closing and then go fully open.

C. The valve will close fully and remain fully closed.

D. The valve will close fully and then go fully open.

Answer 41

The valve will close fully and remain fully closed.

Question 42

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully closed and has a 10-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
An operator takes the control switch to OPEN momentarily and the valve begins to open. Five
seconds later, the operator takes the control switch to CLOSE momentarily and releases the switch.
Which one of the following describes the valve response when the control switch is taken to CLOSE
momentarily and released?

A. The valve will stop opening and remain partially open.

B. The valve will stop opening and then go fully closed.

C. The valve will open fully and remain fully open.

D. The valve will open fully and then go fully closed.

Answer 42

The valve will stop opening and remain partially open.

Question 43

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully closed and has a 10-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
The operator takes the control switch to OPEN momentarily and the valve begins to open. Five
seconds later, the operator takes the switch to CLOSE momentarily and then releases the switch.
Which one of the following describes the valve response after the switch is released?

A. The valve will stop opening and remain partially open.

B. The valve will stop opening and then go fully closed.

C. The valve will open fully and remain fully open.

D. The valve will open fully and then go fully closed.

Answer 43

The valve will open fully and remain fully open.

Question 44

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully open and has a 10-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
The operator takes the control switch to CLOSE. Two seconds later, after verifying the valve is
closing, the operator releases the control switch. Which one of the following describes the valve
motor control circuit alarm response after the switch is released?

A. The alarm will continue to actuate for approximately 8 seconds.

B. The alarm will continue to actuate until additional operator action is taken.

C. The alarm will actuate after approximately 8 seconds.

D. The alarm will not actuate until additional operator action is taken.

Answer 44

The alarm will continue to actuate for approximately 8 seconds.

Question 45

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully open and has a 16-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
An operator takes the control switch to CLOSE. Two seconds later, after verifying the valve is
closing, the operator releases the control switch. When the valve stops moving, what will be the
status of the alarm and the red (R) and green (G) indicating lights?
Alarm
Red Ind.
Light
Green Ind.
Light

A. On On On

B. On Off On

C. Off On Off

D. Off Off Off

Answer 45

On On On

Question 46

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully open and has a 10-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
The operator takes the control switch to CLOSE. Two seconds later, after verifying the valve is
closing, the operator releases the control switch. Which one of the following describes the valve
motor control circuit alarm response after the switch is released?

A. The alarm will actuate after approximately 8 seconds.

B. The alarm will not actuate until additional operator action is taken.

C. The alarm will continue to actuate for approximately 8 seconds.

D. The alarm will continue to actuate until additional operator action is taken.

Answer 46

The alarm will not actuate until additional operator action is taken.

Question 47

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully open and has a 16-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
An operator takes the control switch to CLOSE. Two seconds later, after verifying the valve is
closing, the operator releases the control switch. When the valve stops moving, what will be the
status of the alarm and the red (R) and green (G) indicating lights?
Alarm
Red Ind.
Light
Green Ind.
Light

A. On On On

B. On Off Off

C. Off On Off

D. Off Off On

Answer 47

Off Off On

Question 48

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully open and has an 8-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings. All contacts
are functional, except for contact K2-2 which has failed open.
An operator takes the control switch to CLOSE. Four seconds later, the operator releases the control
switch. When the valve stops moving, what will be the status of the alarm and the red (R) and green
(G) indicating lights?
Alarm
Red Ind.
Light
Green Ind.
Light

A. On On On

B. On Off Off

C. Off On Off

D. Off Off On

Answer 48

On On On

Question 49

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully closed and has a 10-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
The operator takes the control switch to OPEN. Two seconds later, after verifying the valve is
opening, the operator releases the control switch. Which one of the following describes the alarm
response after the control switch is released?

A. The alarm will activate after approximately 8 seconds.

B. The alarm will not activate until additional operator action is taken.

C. The alarm will remain activated for approximately 8 seconds, and then deactivate.

D. The alarm will remain activated until additional operator action is taken.

Answer 49

The alarm will remain activated until additional operator action is taken.

Question 50

Refer to the drawing of a valve motor control circuit (see figure below) for a valve that is currently
fully closed and has a 10-second stroke time.
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are
shown open/closed according to the standard convention for control circuit drawings.
The operator takes the control switch to OPEN. Two seconds later, after verifying the valve is
opening, the operator releases the control switch. Which one of the following describes the valve
motor control circuit alarm response after the switch is released?

A. The alarm will actuate after approximately 8 seconds.

B. The alarm will not actuate until additional operator action is taken.

C. The alarm will continue to actuate for approximately 8 seconds.

D. The alarm will continue to actuate until additional operator action is taken.

Answer 50

The alarm will actuate after approximately 8 seconds.

Question 51

Refer to the drawing of a valve motor control circuit (see figure below).
The valve is currently closed with the contact configuration as shown. If the S1 pushbutton is
depressed, the valve will __________; and when the S1 pushbutton is subsequently released, the valve
will __________.

A. open; close

B. open; remain open

C. remain closed; open

D. remain closed; remain closed

Answer 51

open; remain open

Question 52

Which one of the following is an unsafe practice if performed while working on or near energized
electrical equipment?

A. Using two hands for balance and to prevent dropping tools onto energized equipment.

B. Standing on insulating rubber material to increase the electrical resistance of the body to ground.

C. Having a person stand by to deenergize the equipment in the event of an emergency.

D. Covering exposed energized circuits with insulating material to prevent inadvertent contact.

Answer 52

Using two hands for balance and to prevent dropping tools onto energized equipment.

Question 53

A 480 VAC motor is supplied power via an electrical disconnect in series with a breaker. Which one
of the following describes the proper operations to isolate power to the motor?

A. Open the disconnect first, then the breaker.

B. Open the breaker first, then the disconnect.

C. Open the device that is closest to the motor first.

D. Open the device that is closest to the power source first.

Answer 53

Open the breaker first, then the disconnect.

Question 54

Which one of the following is an unsafe practice if performed while working on or near energized
electrical equipment?

A. Use insulated tools to prevent inadvertent contact with adjacent equipment.

B. Cover exposed energized circuits with insulating material to prevent inadvertent contact.

C. Attach a metal strap from your body to a nearby neutral ground to ensure that you are grounded.

D. Have a person standing by with the ability to remove you from the equipment in the event of an
emergency.

Answer 54

Attach a metal strap from your body to a nearby neutral ground to ensure that you are grounded.

Question 55

The primary reason for isolating emergency electrical loads from their power supply bus prior to
energizing the bus via the emergency diesel generator is to prevent an…

A. overcurrent condition on the generator.

B. overcurrent condition on the loads.

C. underfrequency condition on the generator.

D. underfrequency condition on the loads.

Answer 55

overcurrent condition on the generator.

Question 56

A main generator is being connected to an infinite power grid that is operating at 60 Hz. Generator
output voltage is equal to the grid voltage but generator frequency is at 57 Hz.
Which one of the following generator conditions is most likely to occur if the generator output breaker
is closed with voltages in phase (synchronized), but with the existing frequency difference? (Assume
no generator breaker protective trip occurs.)

A. Reverse power

B. Underfrequency

C. Undervoltage

D. Overspeed

Answer 56

Reverse power

Question 57

Closing the output breaker of a three-phase generator onto a deenergized bus can…

A. produce an overvoltage condition on the bus.

B. produce an overcurrent condition on the generator if the bus was not first unloaded.

C. result in a reverse power trip of the generator circuit breaker if generator frequency is low.

D. result in large reactive currents in the generator.

Answer 57

produce an overcurrent condition on the generator if the bus was not first unloaded.

Question 58

A main generator is being paralleled to an infinite power grid. Closing the output breaker of the
generator with the frequency of the generator 0.1 Hz higher than grid frequency will result in the
generator…

A. behaving as a real load to the grid.

B. behaving as a reactive load to the grid.

C. supplying a portion of the grid reactive load.

D. supplying a portion of the grid real load.

Answer 58

supplying a portion of the grid real load.

Question 59

Which one of the following generator conditions is most likely to result in equipment damage from
high current flow?

A. Tripping the output breaker under full-load conditions.

B. Tripping the generator prime mover under full-load conditions.

C. Closing the output breaker onto a bus that has a short-circuit fault.

D. Closing the output breaker onto a bus that has an open-circuit fault.

Answer 59

Closing the output breaker onto a bus that has a short-circuit fault.

Question 60

A main generator is about to be connected to an infinite power grid. Closing the generator output
breaker with the generator voltage slightly lower than grid voltage and with generator frequency
slightly higher than grid frequency will initially result in: (Assume no generator breaker protective
trip occurs.)

A. the generator supplying reactive power to the grid.

B. the generator attaining a leading power factor.

C. the generator acting as a real load to the grid.

D. motoring of the generator.

Answer 60

the generator attaining a leading power factor.

Question 61

A main generator is being paralleled to the power grid. Generator voltage has been properly adjusted
and the synchroscope is rotating slowly in the clockwise direction.
The generator breaker must be closed just as the synchroscope pointer reaches the 12 o’clock position
to prevent…

A. motoring of the generator, due to unequal frequencies.

B. excessive MW load transfer to the generator, due to unequal frequencies.

C. excessive MW load transfer to the generator, due to out-of-phase voltages.

D. excessive arcing within the generator output breaker, due to out-of-phase voltages.

Answer 61

excessive arcing within the generator output breaker, due to out-of-phase voltages.

Question 62

Which one of the following evolutions will draw the highest current from the main generator during
operation of the output breaker?

A. Opening the output breaker under full-load conditions.

B. Opening the output breaker under no-load conditions.

C. Closing the output breaker with voltages out of phase.

D. Closing the output breaker with voltages in phase.

Answer 62

Closing the output breaker with voltages out of phase.

Question 63

During paralleling operations of the main generator to an infinite power grid, closing the generator
output breaker with the frequency of the generator at 61 hertz and the grid frequency at 60 hertz will…

A. cause the generator to immediately increase load.

B. trip open the generator breaker on reverse power.

C. cause the generator voltage to increase.

D. cause the generator current to decrease.

Answer 63

cause the generator to immediately increase load.

Question 64

Under which one of the following pre-existing conditions will closing a breaker between two electrical
generators cause a sudden large and possibly damaging mechanical torque to be exerted on both of the
generators?

A. One generator is supplying a 3 percent higher voltage than the other.

B. One generator is supplying a 3 percent higher frequency than the other.

C. The voltage of one generator is out of phase with the other by 30 degrees.

D. The capacity of one generator is twice that of the other generator.

Answer 64

The voltage of one generator is out of phase with the other by 30 degrees.

Question 65

A main generator is about to be connected to an infinite power grid with the following conditions:
Generator frequency = 59.5 Hz
Grid frequency: = 59.8 Hz
Generator voltage: = 115.1 KV
Grid voltage: = 114.8 KV
When the generator output breaker is closed, the generator will…

A. acquire real load and reactive load.

B. acquire real load but become a reactive load to the grid.

C. become a real load to the grid but acquire reactive load.

D. become a real load and a reactive load to the grid.

Answer 65

become a real load to the grid but acquire reactive load.

Question 66

A main generator is about to be connected to an infinite power grid. Closing the generator output
breaker with generator and grid voltages matched, but with generator frequency lower than grid
frequency will initially result in the generator…

A. picking up a portion of the grid real load.

B. picking up a portion of the grid reactive load.

C. experiencing reverse power conditions.

D. experiencing overspeed conditions.

Answer 66

experiencing reverse power conditions.

Question 67

A main generator is about to be connected to an infinite power grid. Closing the generator output
breaker with the __________ of the generator higher than that of the grid will initially result in
generator real load __________.

A. frequency; decreasing
.

B. frequency; increasing

C. voltage; decreasing

D. voltage; increasing

Answer 67

frequency; increasing

Question 68

A main generator is about to be connected to an infinite power grid. Closing the generator output
breaker with generator and grid voltages matched, but with generator frequency 0.1 Hz higher than
grid frequency will initially result in the generator…

A. picking up a portion of the grid real load.

B. picking up a portion of the grid reactive load.

C. experiencing reverse power conditions.

D. experiencing overspeed conditions.

Answer 68

picking up a portion of the grid real load.

Question 69

A main generator is about to be connected to an infinite power grid with the following conditions:
Generator frequency = 59.8 Hz
Grid frequency = 59.5 Hz
Generator voltage = 114.8 KV
Grid voltage = 115.1 KV
When the generator output breaker is closed, the generator will initially…

A. acquire real load and reactive load.

B. acquire real load, but become a reactive load to the grid.

C. become a real load to the grid, but acquire reactive load.

D. become a real load and a reactive load to the grid.

Answer 69

acquire real load, but become a reactive load to the grid.

Question 70

A main generator is being paralleled to an infinite power grid. Generator voltage has been properly
adjusted and the synchroscope is rotating slowly in the counterclockwise direction.
If the generator breaker is closed just prior to the synchroscope pointer reaching the 12 o’clock
position, which one of the following is most likely to occur?

A. The breaker will close and the generator will supply only MW to the grid.

B. The breaker will close and the generator will supply both MW and MVAR to the grid.

C. The breaker will close and then open due to overcurrent.

D. The breaker will close and then open due to reverse power.

Answer 70

The breaker will close and then open due to reverse power.

Question 71

A main generator is being connected to an infinite power grid. Which one of the following will occur
if the generator output breaker is closed with generator frequency 0.1 Hz lower than power grid
frequency? (Assume that no generator protection relay actuates.)

A. The generator will motorize.

B. The generator will accept too much load.

C. The voltage of the generator will decrease to compensate for the lower frequency.

D. The entire connected system will operate at the frequency of the lowest frequency (the oncoming)
generator.

Answer 71

The generator will motorize.

Question 72

A main generator is being prepared for paralleling with an infinite power grid. Which one of the
following indicates that the main generator and grid voltages are in phase?

A. The synchroscope pointer is at the 12 o’clock position.

B. The frequency of the generator is equal to the frequency of the grid.

C. The synchroscope pointer is turning slowly in the clockwise direction.

D. The synchroscope pointer is turning slowly in the counterclockwise direction.

Answer 72

The synchroscope pointer is at the 12 o’clock position.

Question 73

A main generator is about to be connected to an infinite power grid. Which one of the following
conditions will cause the main generator to immediately supply reactive power (MVAR) to the grid
when the generator output breaker is closed?

A. Generator voltage is slightly higher than grid voltage.

B. Generator voltage is slightly lower than grid voltage.

C. The synchroscope is turning slowly in the clockwise direction.

D. The synchroscope is turning slowly in the counterclockwise direction.

Answer 73

Generator voltage is slightly higher than grid voltage.

Question 74

Two identical 1,000 MW electrical generators are being connected to the same electrical bus.
Generator A is currently supplying the bus. Generator A and B output indications are as follows:
Generator A Generator B
4,160 Volts 4,140 Volts
60.2 Hertz 60.8 Hertz
25 MW 0 MW
10 MVAR 0 MVAR
When the output breaker for generator B is closed, which generator is more likely to trip on reverse
power?

A. Generator A, due to the higher initial voltage.

B. Generator A, due to the lower initial frequency.

C. Generator B, due to the lower initial voltage.

D. Generator B, due to the higher initial frequency.

Answer 74

Generator A, due to the lower initial frequency.

Question 75

A main generator is about to be connected to an infinite power grid. Generator voltage equals grid
voltage and the synchroscope is rotating slowly in the clockwise direction. The generator breaker is
closed just as the synchroscope pointer reaches the 12 o’clock position.
Which one of the following will occur after the breaker is closed?

A. The breaker will remain closed and the generator will supply only MW to the grid.

B. The breaker will remain closed and the generator will supply both MW and MVAR to the grid.

C. The breaker will trip open due to overcurrent.

D. The breaker will trip open due to reverse power.

Answer 75

The breaker will remain closed and the generator will supply only MW to the grid.

Question 76

A main generator is being prepared for paralleling with an infinite power grid. Which one of the
following indicates that the generator and grid voltages are in phase?

A. The voltage of the generator is equal to the voltage of the grid.

B. The frequency of the generator is equal to the frequency of the grid.

C. The synchroscope pointer is turning slowly in the clockwise direction.

D. The synchroscope pointer is passing through the 12 o’clock position.

Answer 76

The synchroscope pointer is passing through the 12 o’clock position.

Question 77

An isolated electrical bus is being supplied by generator A. Generator B is about to be connected to
the same electrical bus. Generators A and B are both rated at 1,000 MW. Generator A and B output
indications are as follows:
Generator A Generator B
4,140 Volts 4,160 Volts
60.8 Hertz 60.2 Hertz
25 MW 0 MW
10 MVAR (out) 0 MVAR
When the output breaker for generator B is closed, which generator is more likely to trip on reverse
power?

A. Generator A, due to the lower initial voltage.

B. Generator A, due to the higher initial frequency.

C. Generator B, due to the higher initial voltage.

D. Generator B, due to the lower initial frequency.

Answer 77

Generator B, due to the lower initial frequency.

Question 78

A main generator is about to be connected to an infinite power grid. Generator voltage is slightly
higher than grid voltage and the synchroscope is rotating slowly in the clockwise direction. The
generator breaker is closed just as the synchroscope pointer reaches the 12 o’clock position.
Which one of the following will occur after the breaker is closed?

A. The breaker will remain closed and the generator will supply only MW to the grid.

B. The breaker will remain closed and the generator will supply both MW and MVAR to the grid.

C. The breaker will open due to overcurrent.

D. The breaker will open due to reverse power.

Answer 78

The breaker will remain closed and the generator will supply both MW and MVAR to the grid.

Question 79

A main generator is being prepared for paralleling with an infinite power grid. At which one of the
following synchroscope pointer positions is the main generator output voltage the farthest out of phase
with the grid voltage?
A. 3 o’clock
B. 6 o’clock
C. 9 o’clock
D. 12 o’clock

Question 80

A main generator is being prepared for paralleling with an infinite power grid. At which one of the
following synchroscope pointer positions is the main generator output voltage the farthest out of phase
with the grid voltage?

A. 3 o’clock

B. 6 o’clock

C. 9 o’clock

D. 12 o’clock

Answer 80

6 o’clock

Question 81

A main generator is about to be connected to an infinite power grid. Generator voltage is slightly
higher than grid voltage and the synchroscope is rotating slowly in the clockwise direction. The
generator breaker is closed just as the synchroscope pointer reaches the 3 o’clock position.
Which one of the following is most likely to occur after the breaker is closed?

A. The breaker will remain closed and the generator will supply only MW to the grid.

B. The breaker will remain closed and the generator will supply both MW and MVAR to the grid.

C. The breaker will open due to overcurrent.

D. The breaker will open due to reverse power.

Answer 81

The breaker will open due to overcurrent.

Question 82

A main generator is being paralleled to an infinite power grid with the following conditions:
Generator frequency = 59.9 Hz
Grid frequency = 60.1 Hz
Generator voltage = 114.8 KV
Grid voltage = 115.1 KV
When the generator output breaker is closed, the generator will…

A. acquire real load and reactive load.

B. acquire real load, but become a reactive load to the grid.

C. become a real load to the grid, but acquire reactive load.

D. become a real load and a reactive load to the grid.

Answer 82

become a real load and a reactive load to the grid.

Question 83

A main generator is about to be connected to an infinite power grid with the following conditions:
Generator frequency = 60.1 Hz
Grid frequency = 59.9 Hz
Generator voltage = 115.1 KV
Grid voltage = 114.8 KV
When the generator output breaker is closed, the generator will…

A. acquire real load and reactive load.

B. acquire real load, but become a reactive load to the grid.

C. become a real load to the grid, but acquire reactive load.

D. become a real load and a reactive load to the grid.

Answer 83

acquire real load and reactive load.

Question 86

A main generator is about to be connected to an infinite power grid. The main generator has the
following initial conditions:
Generator frequency = 59.9 Hz Generator voltage = 115.1 KV
Grid frequency = 60.1 Hz Grid voltage = 114.8 KV
When the generator output breaker is closed, the generator will…

A. acquire real load and reactive load.

B. acquire real load, but become a reactive load to the grid.

C. become a real load and a reactive load to the grid.

D. become a real load to the grid, but acquire reactive load.

Answer 86

become a real load to the grid, but acquire reactive load.

Question 87

During a routine inspection of a main generator output breaker, a technician discovers severely
damaged main contact surfaces. Which one of the following is the most likely cause of the damaged
contact surfaces?

A. The main generator breaker automatically tripped open after it was closed with the generator and
power grid voltages 60 degrees out of phase.

B. The main generator breaker automatically tripped open due to a faulty trip relay actuation while
the main generator was operating unloaded.

C. The main generator breaker automatically tripped open on a loss of offsite power while the main
generator was operating at its maximum rated load.

D. The main generator breaker automatically tripped open after it was closed with the generator and
power grid voltages in phase but with generator frequency 0.2 Hz lower than power grid
frequency.

Answer 87

The main generator breaker automatically tripped open after it was closed with the generator and
power grid voltages 60 degrees out of phase.

Question 88

A main generator is about to be connected to an infinite power grid. Generator output frequency is
slightly higher than grid frequency and generator output voltage is equal to grid voltage.
Which one of the following situations will exist when the main generator electrical conditions stabilize
immediately after the generator output breaker is closed? (Assume no additional operator actions are
taken.)

A. Generator output current will be 0.

B. Generator power factor will be 0.

C. Generator output MVAR will be 0.

D. Generator output MW will be 0.

Answer 88

Generator output MVAR will be 0.

Question 89

A main generator is being connected to an infinite power grid. The following frequencies exist just
prior to closing the generator output breaker:
Generator frequency = 59.9 Hz
Grid frequency = 60.1 Hz
When conditions stabilize just after the generator output breaker is closed, the generator frequency
will be __________; and the grid frequency will be __________.

A. 59.9 Hz; 59.9 Hz

B. 59.9 Hz; 60.1 Hz

C. 60.0 Hz; 60.0 Hz

D. 60.1 Hz; 60.1 Hz

Answer 89

60.1 Hz; 60.1 Hz

Question 90

A diesel generator (DG) was initially operating at 80 percent of rated load supplying an isolated
electrical bus when a malfunction caused the DG output breaker to trip. The breakers for all of the
bus loads–all of which are large motors–remained closed, preparing the motors to restart upon
restoration of power to the bus.
The DG output breaker has been repaired. With all of the bus load breakers still closed, which one of
the following will occur when the DG output breaker is closed to reenergize the bus?

A. The DG will become lightly loaded.

B. The DG will return directly to its initial load.

C. The DG will experience slight overload conditions.

D. The DG will experience severe overload conditions.

Answer 90

The DG will experience severe overload conditions.

Question 91

A main generator output breaker is about to be closed to connect the main generator to the power grid
via the main transformer. The main transformer voltage and frequency are as follows:
Voltage = 20,000 volts
Frequency = 60.0 Hz
Which combination of main generator voltage and frequency will ensure that the main generator will
immediately supply real (MW) and reactive (MVAR) electrical power to the power grid when the
main generator output breaker is closed?

A. 19,950 volts; 59.9 Hz

B. 19,950 volts; 60.1 Hz

C. 20,050 volts; 59.9 Hz

D. 20,050 volts; 60.1 Hz

Answer 91

20,050 volts; 60.1 Hz

Question 92

If a main generator output breaker is closed when the generator output voltage is 5 degrees out of
phase with the power grid voltage, the main generator will experience a __________ stress; if the
breaker remains closed and no additional operator action is taken, the main generator voltage will
__________ with the grid voltage.

A. minor; remain out of phase

B. minor; become locked into phase

C. potentially damaging; remain out of phase

D. potentially damaging; become locked into phase

Answer 92

minor; become locked into phase

Question 93

If a main generator output breaker is closed when the generator output voltage is 90 degrees out of
phase with the power grid voltage, the main generator will experience a __________ stress; if the
breaker remains closed and no additional operator action is taken, the main generator voltage will
__________ with the grid voltage.

A minor; remain out of phase

B. minor; become locked into phase

C. potentially damaging; remain out of phase

D. potentially damaging; become locked into phase

Answer 93

potentially damaging; become locked into phase

Question 94

The main generator output breaker was just closed to connect the main generator to the main
transformer. Just before the breaker was closed, the following parameter values existed:
Main Generator Main Transformer
20,000 volts 20,050 volts
60.0 Hz 59.9 Hz
With no additional operator action, the main generator stabilized with the following parameter values:
25 MW
15 MVAR (in)
Now consider this following alternate set of parameters values:
Main Generator Main Transformer
20,020 volts 20,050 volts
60.1 Hz 59.9 Hz
If the alternate set of parameter values had existed just before the breaker was closed, the resulting
main generator MW value would have been __________; and the resulting main generator
MVAR (in) value would have been __________.

A. smaller; larger

B. smaller; smaller

C. larger; larger

D. larger; smaller

Answer 94

larger; smaller

Question 95

The main generator output breaker was just closed to connect the main generator to the main
transformer. Just before the breaker was closed, the following parameter values existed:
Main Generator Main Transformer
20,060 volts 20,020 volts
60.1 Hz 59.9 Hz
With no additional operator action, the main generator stabilized as follows:
25 MW
15 MVAR (out)
Now consider the following alternate set of parameters values:
Main Generator Main Transformer
20,040 volts 20,020 volts
60.0 Hz 59.9 Hz
If the alternate set of parameter values existed just before the main generator output breaker was
closed, the resulting main generator MW value would be __________; and the resulting main
generator MVAR (out) value would be __________.

A. smaller; larger

B. smaller; smaller

C. larger; larger

D. larger; smaller

Answer 95

smaller; smaller

Question 96

The main generator output breaker was just closed to connect the main generator to the main
transformer. Just before the breaker was closed, the following parameter values existed:
Main Generator Main Transformer
20,000 volts 20,050 volts
60.1 Hz 59.9 Hz
With no additional operator action, the main generator stabilized with the following parameter values:
25 MW
15 MVAR (in)
Now consider this following alternate set of parameters values:
Main Generator Main Transformer
20,020 volts 20,050 volts
60.0 Hz 59.9 Hz
If the alternate set of parameter values had existed just before the breaker was closed, the resulting
main generator MW value would have been __________; and the resulting main generator
MVAR (in) value would have been __________.

A. larger; larger

B. larger; smaller

C. smaller; larger

D. smaller; smaller

Answer 96

smaller; smaller

Question 97

When a typical 4,160 volt breaker is racked to the TEST position, control power is __________ the
breaker; and the breaker is __________ the load.

A. removed from; isolated from

B. removed from; connected to

C. available to; isolated from

D. available to; connected to

Answer 97

available to; isolated from

Question 98

Which one of the following functions or capabilities would remain following a loss of control power to
a typical 480 VAC bus feeder breaker?

A. Remote breaker control capability.

B. Breaker closing spring automatic recharging capability.

C. Remote bus voltage indication.

D. Remote breaker position indication.

Answer 98

Remote bus voltage indication.

Question 99

Which one of the following statements describes the use of high-voltage disconnect switches?

A. Their use should be limited to normal load current interruption.

B. They may be used to isolate transformers in an unloaded network.

C. They trip open like circuit breakers, but must be manually closed.

D. They must be closed with caution when under load because of possible arcing.

Answer 99

They may be used to isolate transformers in an unloaded network.

Question 100

The function of high-voltage disconnect switches is to provide __________ electrical isolation of
equipment during __________ conditions.

A. manual; no-load

B. manual; overload

C. automatic; no-load

D. automatic; overload

Answer 100

manual; no-load

Question 101

High-voltage disconnect switches are used to…

A. adjust the output voltage range from a main power transformer.

B. protect bus feeder breakers by opening upon bus short-circuit faults.

C. provide equipment isolation under no-load conditions.

D. bypass and isolate an electrical bus while maintaining the downstream buses energized.

Answer 101

provide equipment isolation under no-load conditions.

Question 102

What is an advantage of using high-voltage disconnect switches instead of breakers to isolate main
power transformers?

A. Disconnect switches can be operated either locally or remotely.

B. Disconnect switches provide direct visual indication that the circuit is broken.

C. Disconnect switches are cheaper and provide the same automatic protection as a breaker.

D. Disconnect switches are capable of interrupting a higher current flow with less heating than a
breaker

Answer 102

Disconnect switches provide direct visual indication that the circuit is broken.

Question 103

Which one of the following describes a characteristic of high-voltage disconnect switches?

A. They close automatically requiring no operator action.

B. They should not be used to interrupt a circuit under load.

C. They require a remote means of indication to determine actual position.

D. They should be connected so that they ground the supply bus prior to opening a circuit.

Answer 103

They should not be used to interrupt a circuit under load.

Question 104

Typical high-voltage disconnect switches are designed to…

A. protect circuits during overcurrent conditions.

B. automatically trip open to protect breakers.

C. isolate equipment electrically during no-load conditions.

D. interrupt circuits under load.

Answer 104

isolate equipment electrically during no-load conditions.

Question 105

Typical high-voltage transformer disconnect switches are designed to…

A. automatically protect the transformer from overcurrent conditions.

B. automatically trip open prior to transformer output breaker trip.

C. manually isolate the transformer during no-load conditions.

D. manually interrupt the transformer output circuit under any load when grounds are detected.

Answer 105

manually isolate the transformer during no-load conditions.

Question 106

Refer to the simplified drawing of an electrical distribution system showing 7.2 KV switchgear,
step-down transformers, and 480 V motor control centers (MCCs) (see figure below).
The high voltage side of each step-down transformer has a remote-operated disconnect to allow
transformer maintenance while keeping the other transformers in service. The control circuit for each
disconnect is position-interlocked with the associated MCC feeder breaker.
Which one of the following describes the purpose served by the interlock?

A. Prevent damage to the disconnect.

B. Prevent damage to the transformer.

C. Prevent damage to the feeder breaker.

D. Prevent damage to the 480V MCC.

Answer 106

Prevent damage to the disconnect.

Question 107

A 480 VAC motor control center supplies a load through a breaker and a manual disconnect switch.
Which one of the following sequences will provide the greatest level of personnel safety when
de-energizing the load for maintenance, and when re-energizing the load after the maintenance is
complete?

DE-ENERGIZING RE-

ENERGIZING

A. Open breaker first Shut breaker first

B. Open breaker first Shut disconnect switch first

C. Open disconnect switch first Shut breaker first

D. Open disconnect switch first Shut disconnect switch first

Answer 107

Open breaker first Shut disconnect switch first

Question 108

Refer to the simplified drawing of an electrical distribution system showing 7.2 KV switchgear,
step-down transformers, and 480 V motor control centers (MCCs) (see figure below).
The high voltage side of each step-down transformer has a remote-operated disconnect. The control
circuit for each disconnect is position-interlocked with the associated MCC feeder breaker. Which
one of the following describes the interlock operating scheme that will provide the greatest protection
for the disconnect?

A. Permits opening the feeder breaker only if the disconnect is closed.

B. Permits opening the feeder breaker only if the disconnect is open.

C. Permits opening the disconnect only if the feeder breaker is closed.

D. Permits opening the disconnect only if the feeder breaker is open.

Answer 108

Permits opening the disconnect only if the feeder breaker is open.

Question 109

The following remote indications are observed for a 480 VAC load center supply breaker. (The
breaker is normally open.)
Red indicating light is lit.
Green indicating light is out.
Load center voltage indicates 0 volts.
Breaker incoming voltage indicates 480 volts.
What is the condition of the breaker?

A. Open and racked in

B. Closed and racked in

C. Open and racked to the TEST position

D. Closed and racked to the TEST position

Answer 109

Closed and racked to the TEST position

Question 110

The following indications are observed in the control room for a normally-open motor control center
(MCC) breaker that directly starts/stops a 480 VAC motor:
Red position indicating light is out.
Green position indicating light is out.
Motor ammeter indicates normal load current.
Assuming one of the indicating lights is burned out, what is the condition of the breaker?

A. Open and racked in

B. Open and racked to the TEST position

C. Closed and racked in

D. Closed and racked to the TEST position

Answer 110

Closed and racked in

Question 111

The following indications are observed in the control room for a normally-open motor control center
(MCC) breaker that directly starts/stops a 480 VAC motor:
Red position indicating light is lit.
Green position indicating light is out.
Motor load current indicates 0 amps.
MCC voltage indicates 480 volts.
What is the condition of the breaker?

A. Open and racked in

B. Closed and racked in

C. Open and racked to the TEST position

D. Closed and racked to the TEST position

Answer 111

Closed and racked to the TEST position

Question 112

The following indications are observed in the control room for a normally-open breaker that directly
starts/stops a 480 VAC motor:
Red position indicating light is lit.
Green position indicating light is out.
Load current indicates 50 amps.
Supply voltage indicates 480 volts.
What is the condition of the breaker?

A. Open and racked to the TEST position

B. Closed and racked to the TEST position

C. Open and racked in

D. Closed and racked in

Answer 112

Closed and racked in

Question 113

While remotely investigating the condition of a normally-open breaker that feeds a motor control
center (MCC), an operator observes the following indications:
Green breaker position indicating light is out.
Red breaker position indicating light is lit.
MCC voltmeter indicates normal voltage.
MCC ammeter indicates zero amperes.
Based on these indications, the operator should report that the breaker is __________ and racked
__________.

A. open; in

B. closed; in

C. open; out

D. closed; out

Answer 113

closed; in

Question 114

While remotely investigating the condition of a typical normally-open motor control center (MCC)
feeder breaker, an operator observes the following indications:
Green breaker position indicating light is lit.
Red breaker position indicating light is out.
MCC voltmeter indicates zero volts.
MCC ammeter indicates zero amperes.
Based on these indications, the operator can accurately report that the breaker is open and racked to
__________ position.

A. the OUT

B. the IN

C. the TEST

D. an unknown

Answer 114

an unknown

Question 115

While remotely investigating the condition of a normally-open 480 VAC motor control center (MCC)
feeder breaker, an operator observes the following indications:
Green breaker position indicating light is out.
Red breaker position indicating light is lit.
MCC voltmeter indicates 480 VAC.
MCC ammeter indicates zero amperes.
Based on these indications, the operator should report that the feeder breaker is __________ and
racked __________.

A. open; in

B. closed; in

C. open; to the TEST position

D. closed; to the TEST position

Answer 115

closed; in

Question 116

Given the following indications for an open 4,160 VAC breaker:
All phase overcurrent trip flags are reset.
The control power fuses indicate blown.
The line-side voltmeter indicates 4,160 VAC.
The load-side voltmeter indicates 0 VAC.
Assuming no operator actions were taken since the breaker opened, which one of the following could
have caused the breaker to open?

A. A ground fault caused an automatic breaker trip.

B. A loss of control power caused an automatic breaker trip.

C. An operator opened the breaker locally at the breaker cabinet.

D. An operator opened the breaker remotely from the control room.

Answer 116

An operator opened the breaker locally at the breaker cabinet.

Question 117

While remotely investigating the condition of a normally-open feeder breaker to a 480 VAC motor
control center (MCC), a control room operator observes the following indications:
Green breaker position indicating light is out.
Red breaker position indicating light is lit.
MCC voltmeter indicates 0 VAC.
MCC ammeter indicates zero amperes.
Based on these indications, the operator should report that the feeder breaker is __________ and
racked __________.

A. open; in

B. closed; out

C. open; to the TEST position

D. closed; to the TEST position

Answer 117

closed; to the TEST position

Question 118

While remotely investigating the condition of a normally-open 480 VAC motor control center (MCC)
feeder breaker, an operator observes the following indications:
Green breaker position indicating light is out.
Red breaker position indicating light is lit.
MCC voltmeter indicates 480 VAC.
MCC ammeter indicates zero amperes.
Based on these indications, the operator should report that the feeder breaker is __________ and
racked __________.

A. open; in

B. closed; in

C. open; to an unknown position

D. closed; to an unknown position

Answer 118

closed; in

Question 119

Breaker local overcurrent trip flag indicators, when actuated, indicate that…

A. a breaker trip will occur unless current is reduced.

B. a breaker overcurrent condition is responsible for a breaker trip.

C. an overcurrent condition has cleared and the breaker can be closed.

D. the associated breaker has failed to trip open during an overcurrent condition.

Answer 119

a breaker overcurrent condition is responsible for a breaker trip.

Question 120

Given the following indications for an open 4,160 VAC breaker:
The local OPEN/CLOSED mechanical flag indicates OPEN.
A breaker overcurrent trip flag is actuated on one phase.
The line-side voltmeter indicates 4,160 VAC.
The load-side voltmeter indicates 0 VAC.
Assuming no operator actions were taken since the breaker opened, which one of the following could
have caused the breaker to open?

A. A ground fault caused an automatic breaker trip.

B. A loss of control power caused an automatic breaker trip.

C. An operator opened the breaker locally.

D. An operator opened the breaker from a remote location.

Answer 120

A ground fault caused an automatic breaker trip.