Problem |
Description |
Duration |
Cause |
Effect |
Possible Solution |
Temporary Interruption/Long-term outage |
Planned or accidental total loss of power in a community |
Temporary (2 seconds to 2 minutes) |
Accidents, acts of nature, and automatic operation of utility equipment |
Systems shut down
Loss of product or data |
Uninterruptible power supply (UPS)
Uninterruptible power supply (UPS) and generator |
Momentary Interruption / outage |
Very short planned or accidental power loss |
Milliseconds to a second or two |
Accidents, acts of nature, and automatic operation of utility equipment |
Equipment trips off, programming is lost, computer drives crash |
Uninterruptible power supply (UPS) |
Sag/Swell |
Decrease (sag) or increase (swell) in voltage |
Milliseconds to a few seconds |
Major equipment start-up or shutdown, Short circuits, Undersized electrical circuit |
Memory loss, data errors, dim or bright lights, motor stalling/stopping, equipment shut down |
Uninterruptible power supply (UPS)
Voltage regulator
Power conditioner
Constant voltage transformer (CVT)
Relocate equipment to another circuit |
Surge/Transient |
A surge or transient is a sudden change in voltage up to several thousand volts (also called impulse or spikes) |
Microseconds |
Utility switching operations, starting or stopping heavy equipment or machinery, welding equipment, static discharges, Lighting |
Processing errors, data loss, burned circuit boards, equipment damage |
Surge suppressor
Surge protection device
Uninterruptible power
supply (UPS)
Isolation transformer
Improve grounding |
Noise |
Noise is an unwanted electrical signal of high frequency from other equipment |
Sporadic |
Noise is caused by electro-magnetic interference from appliances, microwave and radar transmissions, radio and TV broadcasts, arc welding, heaters, laser printers, thermostats, loose wiring, or improper grounding |
Disturbs sensitive equipment such as computers, data loss |
Uninterruptible power supply (UPS)
Isolation transformer
Noise filter
Check for proper electrical connection |
Harmonic Distortion |
Harmonic distortion is alternation of the pure sine wave due to non-linear loads on the power supply |
Sporadic |
Harmonic distortion is caused by non-linear loads such as fluorescent lights, computer equipment, and battery chargers |
Overheating of motors, transformers, wiring
Decreased motor performance
Improper operation of electrical system |
Harmonic filter
Isolation transformer
Electrically separate "non- linear" loads from affected equipment
Reroute communications cables away from power cables |
Undervoltage / Overvoltage |
An undervoltage or overvoltage is any long-term change below or above normal voltage |
Lasting more than a minute |
Overloaded wiring or equipment
Large load swings
Improper transformer setting
Voltage drop due to undersized wiring and faulty or poor electrical connections |
Bright or dim lights
Equipment shutdown
Overheating of motor or lights
Process control errors |
Uninterruptible power supply (UPS)
Voltage regulator
Constant voltage transformer (CVT)
Relocate equipment to another circuit
Transformer adjustment
Check for proper electrical connections |
