| Disturbance Type |
Description |
Possible Causes |
Symptoms/Effects |
Potential Solutions |
Power
Outage |
Total interruption of electrical supply:
Momentary outages last from one-half second to 3 seconds
Temporary outages last from 3 seconds to 1 minute
Long-term outages last longer than 1 minute |
Accidents, acts of nature, etc. which require the proper operation of utility equipment (fuses, reclosers, etc.)
Internal short circuits requiring the proper operation of a customer's breakers and fuses |
System shutdown
Loss of computer/ controller memory
Hardware damage
Product loss or damage |
Uninterruptible Power Supply (UPS)
|
|
| Disturbance Type |
Description |
Possible Causes |
Symptoms/Effects |
Potential Solutions |
Transient
(Surge) |
A subcycle disturbance in the AC waveform, resulting in a sharp but brief increase in voltage |
Surges are caused by storms (lightning), operation of utility fuses, reclosers and breakers
Internal causes are turning on or off large equipment and capacitor switching |
Computer lock-up, processing errors and data loss
Burned circuit boards, electrical insulation damage and equipment damage |
Surge protectors
Uninterruptible Power Supplies with built in surge suppression
Isolation transformers
Constant voltage transformer |
|
| Disturbance Type |
Description |
Possible Causes |
Symptoms/Effects |
Potential Solutions |
Sag /
Swell |
Any short-term (one-half cycle to 3 seconds) decrease (sag) or increase (swell) in voltage
Sags account for up to 87% of all power disturbances (according to a Bell Labs study) |
Major equipment shut-down and/or restart
Short circuits
Utility equipment failure or utility switching |
Memory loss and data errors
Equipment shutdown
Flickering lights
Motors stalling or stopping and decreased motor life |
Uninterruptible Power Supply
Constant voltage transformers
Voltage regulators |
|
| Disturbance Type |
Description |
Possible Causes |
Symptoms/Effects |
Potential Solutions |
| Noise |
An unwanted high-frequency electrical signal that alters the normal voltage pattern (sine wave) |
Interference from radio or TV transmission
Operation of electronic equipment |
Lock-up of sensitive equipment
Data loss and processing errors
Distorted audio and video reception |
Uninterruptible Power Supply
Isolation transformers
Power line filters |
|
| Disturbance Type |
Description |
Possible Causes |
Symptoms/Effects |
Potential Solutions |
| Harmonic Distortion |
The alteration of the normal voltage pattern (sine wave) due to equipment generating frequencies other than the standard 60 cycles per second |
Electronic ballasts and other non-linear loads like switch-mode power supplies and variable frequency drives |
Overheating of electrical equipment and wiring
Decreased motor performance
Improper operation of breakers, relays or fuses |
Harmonic filters
Isolation transformers
Improved wiring and grounding
Isolated loads
Line reactors |
|
| Disturbance Type |
Description |
Possible Causes |
Symptoms/Effects |
Potential Solutions |
| Undervoltage/ Overvoltage |
Any long-term change lasting more than a minute, below or above normal voltage |
Overloaded wiring or equipment
Large load swings or improper transformer settings
Undersized wiring and faulty or poor electrical connections |
Dim or bright lights
Equipment shutdown
Overheating of motors or lights
Reduced efficiency or life of electrical equipment |
Uninterruptible Power Supply
Constant voltage transformers
Verify electrical connections and wiring
Relocate equipment
Reduced voltage motor starters and voltage ride-through equipment |