Definitions
Nonlinear load
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Nonlinear load
Electrical loads in which the instantaneous current is not proportional to the
instantaneous voltage. The load impedance varies with the voltage. Electronic
loads, with diode/capacitor front-ends are nonlinear loads.
Outage
Long term power interruption, longer than 1 minute.
Overvoltage
The voltage is above its nominal value on a long term
(longer than 10 cycles).
Point of Common Coupling (PCC)
Point where utility responsibiltity ends and building owner responsibility begins.
Usually at the main transformer or at the revenue meter.
Power Factor (PF)
The ratio of real power to apparent power. Inductive loads cause current to lag
behind voltage, while capacitive loads cause current to lead voltage. Also the
presence of harmonic currents decrease the Power Factor.
The power factor uses the total rms value, thus including all harmonics, for its
calculation. (see also: Displacement Power Factor)
PF Interpretation
0 to 1 not all supplied power is consumed, reactive power present.
1 device is consuming all supplied power, no reactive power.
-1 device is generating power, current and voltage in phase.
-1 to 0 device generating power, current leads or lags.
Reactive Power
The Reactive Power (VAR) is the reactive component of the apparent power,
caused by a phase shift between ac current and voltage in inductors (coils) and
capacitors.
VARs are present in a distribution system as a result of inductive loads, such
as motors, reactors, and transformers. VAR’s are compensated for by
correction capacitors.
Real Power (see Active Power)
Sag
A sag is a temporary voltage decrease caused by, for
example, large equipment starting up or shutting down.
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