NERC – EPRI
NERC – EPRI EXAM QUESTIONS AND ANSWERS %
CORRECT.
If a generator is producing 500 MW and 200 Mar, is the generator? A. Leading B.
Lagging C. Under excited D. Dropping Answer >>> B. Lagging (Solve for phase
angle, + is lagging, - is leading
What is the IEEE device number for a differential relay? A. 87 B. 86 C. 67 D. 50
Answer >>> A. 87 (See IEEE chart pg. 125)
Can a synchronous machine have a negative torque angle? What does this mean?
A. Yes / the machine is absorbing reactive power B. No / the machine is absorbing
active power C. No / the machine is absorbing reactive power D. Yes / the
machine is absorbing active power Answer >>> D. Yes / the machine is absorbing
active power (pg. 153)
A customer load is fed at 120 volts. The customer voltage is doubled while the
load magnitude stays the same. What effect does this have on the power losses?
A. Doubles the losses B. Halves the losses C. Increases the losses by a factor of
four D. Decreases the losses by a factor of four Answer >>> D. Decreases the
losses by a factor of four (combination of ohms’ law, active power equation, and
voltage drop across distribution systems pg.367)
In a DC circuit, a 100-volt battery is connected to both sides of a 2-ohm resistor.
What is the current through the resistor and the power usage of the resistor? A.
50 amps / 5000 watts B. 40 amps / 80 watts C. 50 amps / 100 watts D. 40 amps /
3200 watts Answer >>> A. 50 amps / 5000 watts (ohms law & watts law)
, NERC – EPRI
The actual voltage is 362 kV on a 345 kV bus. What is the put. voltage? A. 1.0 B.
1.05 C. 1.5 D. .95 Answer >>> B. 1.05 (Ratio of voltages)
A load has a power factor of 0.9 lagging. If the load draws 100 MVA, what is the
MW draw? A. 100 B. 90 C. 111 D. 44 Answer >>> B. 90 MW (Power Factor
Equation - (PF = Active / Complex)
Which of the following is NOT a synchronizing variable? A. Phase angle B.
Frequency difference C. Voltage magnitude difference D. MW flow differential
Answer >>> D. MW flow differential (pg. 138)
In a typical multi-stage steam turbine, the governor control valves control the
steam entry to the: A. high pressure turbine B. intermediate pressure turbine C.
low pressure turbine D. Crossover Answer >>> A. high pressure turbine (no idea,
governor controls input? High pressure turbine is first?)
The high side of a delta-wye connected transformer is connected to a power
system with 199 kV L-G high side voltage. What is the voltage across the winding
of the delta transformer? A. 199 kV B. 230 kV C. 345 kV D. 500 kV Answer >>> C.
345 kV (Divide abcd by 199 for turns ratio. then 199+199+199 (delta wye has
three connections) / turns ratio solved in part 1 should equal answer. So 345 /
199 = 1.73 (199*3)/1.73 = 345
What does the voltage angle represent? Answer >>> The amount by which a
voltage sine wave has shifted left or right with respect to a reference
What does the phase angle represent at a point in a power system? Answer >>>
It is the angular separation between the current and the voltage waves.
NERC – EPRI EXAM QUESTIONS AND ANSWERS %
CORRECT.
If a generator is producing 500 MW and 200 Mar, is the generator? A. Leading B.
Lagging C. Under excited D. Dropping Answer >>> B. Lagging (Solve for phase
angle, + is lagging, - is leading
What is the IEEE device number for a differential relay? A. 87 B. 86 C. 67 D. 50
Answer >>> A. 87 (See IEEE chart pg. 125)
Can a synchronous machine have a negative torque angle? What does this mean?
A. Yes / the machine is absorbing reactive power B. No / the machine is absorbing
active power C. No / the machine is absorbing reactive power D. Yes / the
machine is absorbing active power Answer >>> D. Yes / the machine is absorbing
active power (pg. 153)
A customer load is fed at 120 volts. The customer voltage is doubled while the
load magnitude stays the same. What effect does this have on the power losses?
A. Doubles the losses B. Halves the losses C. Increases the losses by a factor of
four D. Decreases the losses by a factor of four Answer >>> D. Decreases the
losses by a factor of four (combination of ohms’ law, active power equation, and
voltage drop across distribution systems pg.367)
In a DC circuit, a 100-volt battery is connected to both sides of a 2-ohm resistor.
What is the current through the resistor and the power usage of the resistor? A.
50 amps / 5000 watts B. 40 amps / 80 watts C. 50 amps / 100 watts D. 40 amps /
3200 watts Answer >>> A. 50 amps / 5000 watts (ohms law & watts law)
, NERC – EPRI
The actual voltage is 362 kV on a 345 kV bus. What is the put. voltage? A. 1.0 B.
1.05 C. 1.5 D. .95 Answer >>> B. 1.05 (Ratio of voltages)
A load has a power factor of 0.9 lagging. If the load draws 100 MVA, what is the
MW draw? A. 100 B. 90 C. 111 D. 44 Answer >>> B. 90 MW (Power Factor
Equation - (PF = Active / Complex)
Which of the following is NOT a synchronizing variable? A. Phase angle B.
Frequency difference C. Voltage magnitude difference D. MW flow differential
Answer >>> D. MW flow differential (pg. 138)
In a typical multi-stage steam turbine, the governor control valves control the
steam entry to the: A. high pressure turbine B. intermediate pressure turbine C.
low pressure turbine D. Crossover Answer >>> A. high pressure turbine (no idea,
governor controls input? High pressure turbine is first?)
The high side of a delta-wye connected transformer is connected to a power
system with 199 kV L-G high side voltage. What is the voltage across the winding
of the delta transformer? A. 199 kV B. 230 kV C. 345 kV D. 500 kV Answer >>> C.
345 kV (Divide abcd by 199 for turns ratio. then 199+199+199 (delta wye has
three connections) / turns ratio solved in part 1 should equal answer. So 345 /
199 = 1.73 (199*3)/1.73 = 345
What does the voltage angle represent? Answer >>> The amount by which a
voltage sine wave has shifted left or right with respect to a reference
What does the phase angle represent at a point in a power system? Answer >>>
It is the angular separation between the current and the voltage waves.
