| Problem |
Description |
Duration |
Cause |
Effect |
Possible Solution |
Momentary Interruption
|
Very short planned or accidental power loss
|
0.5 cycles to 3 sec
|
Switching Operations attempting to isolate electrical problem and maintain power to your area
|
Equipment trips off
Programming is lost
Disk drive crashes
|
UPS or standby power supply(SPS) for critical loads
|
Temporary Interruption/Long-term outage  |
Planned or accidental total loss of power in a localized area of the service area |
Temporary (3 sec-1min) Long-term (over 1 min) |
Equipment failure Contractors digging into underground conductor wires Vehicle hitting pole Storms |
System shuts down |
Uninterruptible power supply (UPS) for critical loads |
Sag/Swell  |
Brief reductions or increases in voltage |
0.5 cycles to 1 minute. Sags or swell longer than 1 minute are called under voltages or over voltages |
Major equipment start-up or shut-down Short circuits (faults) Undersized electrical wiring |
Memory loss Data errors Dim or bright lights shrinking display screens Equipment shutdown |
Relocate equipment to different electrical circuit within facility Power conditioners or UPS Systems for Critical Loads |
Surge  |
Sudden change in voltage up to several thousand volts (also called impulse, spike, or transient) |
<1msec |
Lightning Turning major equipment on or off Utility switching |
Processing Errors Data loss Burned circuit boards |
Install surge suppressor at main panel (best when used in combination with branch circuit surge suppressor) |
Noise/Harmonic Distortion  |
Continuous distortion of normal voltage |
Steady State |
Electromagnetic interference from appliances, machines, radio, and TV broadcasts Harmonic distortion from nonlinear loads (computers, lights) |
Continuous distortion of normal voltage Random data errors |
Use a noise filter designed for application (sometimes incorporated with surge suppressors) Power conditioner |
