NERC-Transmission Exam | Actual Questions and Answers
Latest Updated 2026/2027 (Graded A+)
•
Current Transformer
- ✔✔Instrument Transformers design for transforming large current magnitudes to
secondary current suitable for relaying and metering. The secondary current flow is
proportional to the larger primary current flow.
•
Cycle
- ✔✔One full sine wave cycle that is divided into 360 Degrees. The waveform passes through
zero, Rises to a maximum, drops back to zero, drops to a minimum, then rises again to zero.
Both current and voltage in North America Power Systems have cycle wave forms that will a
repeat 60 times a second.
•
Fault
- ✔✔An event occurring on an electric system such as a short circuit, a broken wire, or
intermittent connection.
•
Misoperation
- ✔✔The failure of a Composite Protection System to operate as intended for protection
purposes.
•
Overlapping Zone
- ✔✔Where two or more protective relay zones overlap at an electrical circuit of device. This
ensures complete protection of the system.
•
Pilot relaying
- ✔✔Used to provide selective and high-speed tripping for any fault location on the
protected line by establishing Communications between relays.
•
Potential Transformer
- ✔✔Also known as PT's transform primary voltage to a smaller secondary voltage suitable
for metering relaying. The secondary voltage is usually around 120 volts and is proportional
to the higher primary voltage.
•
Power line carrier (PLC)
- ✔✔This is a way of using power lines to carry Communications. It can be used to provide
Communications between protective relays at either end of a transmission line.
, •
Protection system
- ✔✔Protective relays, communication systems, voltage and current sensing devices,
Station DC Supply associated with protective functions, and control circuitry associated
with protective functions.
•
Wave trap
- ✔✔A filter used to remove the power line carrier signal from the line and Route it to the line
protective relays.
•
Zones of protection
- ✔✔The zones areas within which a protective Relay can sense abnormal conditions.
•
Contingency
- ✔✔The unexpected failure or outage of a system component, such as a generator,
transmission line, circuit breaker, switch, or other electrical element.
•
Emergency Rating
- ✔✔The rating as defined by the equipment owner that specifies the level of electrical
loading or output, usually expressed in megawatts (MW) or Mvar or other appropriate units,
that a system, facility, or element can support, produce, or withstand for a finite period. The
rating assumes acceptable loss of equipment life or other physical or safety limitations for
the equipment involved.
•
Facility rating
- ✔✔The maximum or minimum voltage, current, frequency, or real or reactive power flow
through a facility that does not violate the applicable equipment rating of any equipment
comprising the facility.
•
Operation Instructions
- ✔✔A command by operating personnel responsible for the Real-time operation of the
interconnected BES to change or preserve the state, status, output, or input of an Element of
the BES.
•
Operating Reserves
- ✔✔That capability above firm system demand required to provide for regulation, load
forecasting error, equipment forced and scheduled outages and local area protection. It
consists of spinning and non-spinning reserve.
•
Reactive Power
Latest Updated 2026/2027 (Graded A+)
•
Current Transformer
- ✔✔Instrument Transformers design for transforming large current magnitudes to
secondary current suitable for relaying and metering. The secondary current flow is
proportional to the larger primary current flow.
•
Cycle
- ✔✔One full sine wave cycle that is divided into 360 Degrees. The waveform passes through
zero, Rises to a maximum, drops back to zero, drops to a minimum, then rises again to zero.
Both current and voltage in North America Power Systems have cycle wave forms that will a
repeat 60 times a second.
•
Fault
- ✔✔An event occurring on an electric system such as a short circuit, a broken wire, or
intermittent connection.
•
Misoperation
- ✔✔The failure of a Composite Protection System to operate as intended for protection
purposes.
•
Overlapping Zone
- ✔✔Where two or more protective relay zones overlap at an electrical circuit of device. This
ensures complete protection of the system.
•
Pilot relaying
- ✔✔Used to provide selective and high-speed tripping for any fault location on the
protected line by establishing Communications between relays.
•
Potential Transformer
- ✔✔Also known as PT's transform primary voltage to a smaller secondary voltage suitable
for metering relaying. The secondary voltage is usually around 120 volts and is proportional
to the higher primary voltage.
•
Power line carrier (PLC)
- ✔✔This is a way of using power lines to carry Communications. It can be used to provide
Communications between protective relays at either end of a transmission line.
, •
Protection system
- ✔✔Protective relays, communication systems, voltage and current sensing devices,
Station DC Supply associated with protective functions, and control circuitry associated
with protective functions.
•
Wave trap
- ✔✔A filter used to remove the power line carrier signal from the line and Route it to the line
protective relays.
•
Zones of protection
- ✔✔The zones areas within which a protective Relay can sense abnormal conditions.
•
Contingency
- ✔✔The unexpected failure or outage of a system component, such as a generator,
transmission line, circuit breaker, switch, or other electrical element.
•
Emergency Rating
- ✔✔The rating as defined by the equipment owner that specifies the level of electrical
loading or output, usually expressed in megawatts (MW) or Mvar or other appropriate units,
that a system, facility, or element can support, produce, or withstand for a finite period. The
rating assumes acceptable loss of equipment life or other physical or safety limitations for
the equipment involved.
•
Facility rating
- ✔✔The maximum or minimum voltage, current, frequency, or real or reactive power flow
through a facility that does not violate the applicable equipment rating of any equipment
comprising the facility.
•
Operation Instructions
- ✔✔A command by operating personnel responsible for the Real-time operation of the
interconnected BES to change or preserve the state, status, output, or input of an Element of
the BES.
•
Operating Reserves
- ✔✔That capability above firm system demand required to provide for regulation, load
forecasting error, equipment forced and scheduled outages and local area protection. It
consists of spinning and non-spinning reserve.
•
Reactive Power
