EPRI TERMS & DEFINITIONS (A-E) COMPLETE GUIDE
Accelerating power ✔️ans -in a generator, the difference between
the mechanical input power and the electrical outputpower (assuming no
losses). For a generator's torque angle to change, the generatormust have
accelerating power.
Accumulated inadvertent ✔️ans -the accumulation over time of
inadvertent energy. The accumulated inadvertent account of abalancing
authority represents the amount of excess energy a balancing authority
haseither supplied to the interconnection or absorbed from the
interconnection. Balancingauthorities monitor their accumulated inadvertent
to ensure the accounts do not grow too large.
Active power ✔️ans -the component of the complex power that
performs the work. The common unit of activepower is the mw and the
symbol is "p". Active power is sometimes called real power.
Actual interchange ✔️ans -the metered interchange over a specific
interconnection between two physicallyadjacent balancing authorities.
Actual load ✔️ans -the actual mw drawn by a load from the power
system. The actual load will be different fromthe rated or nominal load if the
load's voltage or frequency vary from their nominalvalues.
Adequacy ✔️ans -the ability of the electric system to supply the
aggregate electrical demand and energyrequirements of the end-use
customers at all times, taking into account scheduled and reasonablyexpected
unscheduled outages of system elements.
Adequate regulating margin ✔️ans -the minimum on-line capacity
that can be increased or decreased to allow the system to respond to all
reasonable demand changes in order to be incompliance with the
controlperformance standards.
Adjacent balancing authorities ✔️ans -a balancing authority area
that is interconnected to another balancing authority area either directly or
via a multi-party agreement or transmission tariff.
,Agc pulses ✔️ans -the agc system sends signals to selected
(regulating) generators to adjust their set-points. These signals are sent via
telecommunication equipment. The signals are often called agc pulses.
A-index ✔️ans -a daily index of geomagnetic activity derived as the
average of the eight 3-hourly indices.
A-index watch ✔️ans -an a-index watch is issued when the daily
boulder, colorado a-index is predicted to be greaterthan 20, 30, 50, or 100,
with one day or greater lead-time, in the daily forecasts issued by sec. A-index
watches are issued for valid times corresponding to entire calendar days,
based upon thedaily analyses and forecasts produced by sec. They serve as a
long lead-time prediction of theexpected trend in geomagnetic activity, within
the limits of what the 24-hour a-index value candescribe.
Air-gap ✔️ans -the air space between the rotor and stator of a
motor or generator.
Alternating current (ac) ✔️ans -in an ac system the current and
voltage magnitudes constantly vary or alternate. Current and voltage
magnitudes do not alternate in a dc system.
Alternator ✔️ans -a rotating machine whose output is alternating
voltage and current.
Aluminum cable steel reinforced (acsr) ✔️ans -a common type of
transmission line conductor that comes in many different sizes and designs.
The aluminum is the conductor and the steel provides strength.
Amortisseur winding ✔️ans -a machine winding consisting of a
number of conducting bars attached between the magnetic poles of the
machine's rotor. Amortisseur windings may be used as starter windings or to
help dampen power oscillations.
Ampere ✔️ans -the unit of measurement for current flow, often
stated as "amp".
, Amplitude ✔️ans -the value or magnitude that a waveform has at a
specific point in time.
Analog electronics ✔️ans -electronic circuitry in which the
magnitudes of quantities are used in a continuous manner to perform
functions. For example, input current values may be amplified and used to
perform work in an analog circuit. Analog is different than digital in the sense
that analog circuits use voltage and current magnitudes continuously while
digital circuits use voltage and current to determine the state (on or off) of
elements.
Ancillary services (ferc) ✔️ans -those services that are necessary
to support the transmission of capacity and energy from resources to loads
while maintaining reliable operation of the transmission serviceprovider's
transmission system in accordance with good utility practice.
Angle instability ✔️ans -the opposite of angle stability. When a
power system loses angle stability it enters a period of angle instability. An
angle unstable system has lost some portion of the magnetic bound that holds
sections of the power system in synchronism with one another.
Angle stability ✔️ans -an angle stable power system is one in
which all elements of the power system are bound together via magnetic
forces. For example, an angle stable generator's internal magneticfield rotates
in synchronism (in-step) with the magnetic field of the 3f power system to
which it connects.
Apparent power ✔️ans -the product of voltage and current
phasors. Apparent power comprises both active and reactive power, usually
expressed in kilovoltamperes (kva) or megavolt amperes (mva). Another term
for apparent power is complex power.
Arc ✔️ans -the discharge of current through the air or in a gas.
Arcing horns ✔️ans -an enhancement to a disconnect switch to
increase the switch's current interrupting capability.
Accelerating power ✔️ans -in a generator, the difference between
the mechanical input power and the electrical outputpower (assuming no
losses). For a generator's torque angle to change, the generatormust have
accelerating power.
Accumulated inadvertent ✔️ans -the accumulation over time of
inadvertent energy. The accumulated inadvertent account of abalancing
authority represents the amount of excess energy a balancing authority
haseither supplied to the interconnection or absorbed from the
interconnection. Balancingauthorities monitor their accumulated inadvertent
to ensure the accounts do not grow too large.
Active power ✔️ans -the component of the complex power that
performs the work. The common unit of activepower is the mw and the
symbol is "p". Active power is sometimes called real power.
Actual interchange ✔️ans -the metered interchange over a specific
interconnection between two physicallyadjacent balancing authorities.
Actual load ✔️ans -the actual mw drawn by a load from the power
system. The actual load will be different fromthe rated or nominal load if the
load's voltage or frequency vary from their nominalvalues.
Adequacy ✔️ans -the ability of the electric system to supply the
aggregate electrical demand and energyrequirements of the end-use
customers at all times, taking into account scheduled and reasonablyexpected
unscheduled outages of system elements.
Adequate regulating margin ✔️ans -the minimum on-line capacity
that can be increased or decreased to allow the system to respond to all
reasonable demand changes in order to be incompliance with the
controlperformance standards.
Adjacent balancing authorities ✔️ans -a balancing authority area
that is interconnected to another balancing authority area either directly or
via a multi-party agreement or transmission tariff.
,Agc pulses ✔️ans -the agc system sends signals to selected
(regulating) generators to adjust their set-points. These signals are sent via
telecommunication equipment. The signals are often called agc pulses.
A-index ✔️ans -a daily index of geomagnetic activity derived as the
average of the eight 3-hourly indices.
A-index watch ✔️ans -an a-index watch is issued when the daily
boulder, colorado a-index is predicted to be greaterthan 20, 30, 50, or 100,
with one day or greater lead-time, in the daily forecasts issued by sec. A-index
watches are issued for valid times corresponding to entire calendar days,
based upon thedaily analyses and forecasts produced by sec. They serve as a
long lead-time prediction of theexpected trend in geomagnetic activity, within
the limits of what the 24-hour a-index value candescribe.
Air-gap ✔️ans -the air space between the rotor and stator of a
motor or generator.
Alternating current (ac) ✔️ans -in an ac system the current and
voltage magnitudes constantly vary or alternate. Current and voltage
magnitudes do not alternate in a dc system.
Alternator ✔️ans -a rotating machine whose output is alternating
voltage and current.
Aluminum cable steel reinforced (acsr) ✔️ans -a common type of
transmission line conductor that comes in many different sizes and designs.
The aluminum is the conductor and the steel provides strength.
Amortisseur winding ✔️ans -a machine winding consisting of a
number of conducting bars attached between the magnetic poles of the
machine's rotor. Amortisseur windings may be used as starter windings or to
help dampen power oscillations.
Ampere ✔️ans -the unit of measurement for current flow, often
stated as "amp".
, Amplitude ✔️ans -the value or magnitude that a waveform has at a
specific point in time.
Analog electronics ✔️ans -electronic circuitry in which the
magnitudes of quantities are used in a continuous manner to perform
functions. For example, input current values may be amplified and used to
perform work in an analog circuit. Analog is different than digital in the sense
that analog circuits use voltage and current magnitudes continuously while
digital circuits use voltage and current to determine the state (on or off) of
elements.
Ancillary services (ferc) ✔️ans -those services that are necessary
to support the transmission of capacity and energy from resources to loads
while maintaining reliable operation of the transmission serviceprovider's
transmission system in accordance with good utility practice.
Angle instability ✔️ans -the opposite of angle stability. When a
power system loses angle stability it enters a period of angle instability. An
angle unstable system has lost some portion of the magnetic bound that holds
sections of the power system in synchronism with one another.
Angle stability ✔️ans -an angle stable power system is one in
which all elements of the power system are bound together via magnetic
forces. For example, an angle stable generator's internal magneticfield rotates
in synchronism (in-step) with the magnetic field of the 3f power system to
which it connects.
Apparent power ✔️ans -the product of voltage and current
phasors. Apparent power comprises both active and reactive power, usually
expressed in kilovoltamperes (kva) or megavolt amperes (mva). Another term
for apparent power is complex power.
Arc ✔️ans -the discharge of current through the air or in a gas.
Arcing horns ✔️ans -an enhancement to a disconnect switch to
increase the switch's current interrupting capability.
