| Problem |
Duration |
Cause |
Effect |
Remedy |
Outage
Total loss of power |
Less than a second to several hours |
Storms, downed power lines, auto accidents, small animals, etc. |
Electrical equipment shutdown |
Uninterruptible power supply(UPS)
Battery backup |
Sag
Fluctuation in voltage below normal limits (sometimes called an undervoltage) |
Less than a second up to 2 seconds |
Motor starts, air conditioning start up, turning on heavy loads, lightning, utility or local power system shorts |
Lights dim, data errors, shrinking display screens, memory loss, damaged electronic circuitry in severe cases |
Voltage regulator
Uninterruptible power supply (UPS)
Motor generator |
Surge
Fluctuation in voltage above normal limits (sometimes called an overvoltage) |
Usually less than a second |
Sudden stopping of motors, electric welders, storms, power line switching |
Can cause equipment damage if surge is severe, altered computer data |
Voltage regulator
Uninterruptible power supply (UPS)
Motor generator |
Spike
Sudden change in voltage (up to several thousand volts); one of the most damaging power disturbances |
Microseconds (can be as short as millionths of a second) |
Lightning, static discharges, load switching on utility or within home, faulty wiring |
Data loss and burned circuit boards |
Surge suppressor
Power conditioner
Motor generator |
Electrical Noise
High frequency interference from other equipment (7 kHz-50MHz), lower magnitude, spike-like disturbances |
Sporadic |
Appliances, microwave and radar transmission, radio and TV broadcasts, arc welders, heaters, laser printers, thermostats, electric typewriters, loose wiring, improper grounding, fluorescent lights |
Usually not destructive, can wipe out data |
Isolation transformer Power conditioner Uninterruptible power supply (UPS) |
