
10 COMMON POWER PROBLEMS

AC BLACKOUT
A total loss of utility power occurring for more than 2 cycles

FREQUENCY VARIATION
Frequency change from nominal 60Hz or 50Hz. Operation from engine genera- tors can produce frequency variations

BROWN OUT
Long-term reduced line voltage for an extended period of a few minutes to a few days

NORMAL MODE NOISE
High frequency electrical waveform between line (L) and neutral (N) caused by RFI or EMI interference

VOLTAGE SURGE
Short-term high voltage above 110% of nominal for several cycles

HARMONIC DISTORTION
Distortion of the normal waveform generally caused by nonlinear loads such as rectifiers, switch mode power supplies, and variable frequency drives

POWER SAG
Short-term low voltage caused by starting inrush current of large equipment, utility switching, or a temporary overload

SWITCHING TRANSIENT
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OVERVOLTAGE
Extended periods of increased line voltage ranging from a few minutes to a few days

COMMON MODE NOISE
Electrical Interference that is measured between ground and either neutral (N) or line (L) of a typical AC power line