There are several common power problems that a UPS can correct:
· Power failure — Total loss of utility power, with possibility of severe transient conditions upon failure and/or restoration: Causes electrical equipment to stop working (transients may cause permanent damage).
· Voltage sag – Transient (short term) under-voltage: Causes flickering of lights.
· Voltage spike – Transient (short term) over-voltage i.e. spike or peak: Causes wear or acute damage to electronic equipment.
· Under-voltage – Low line voltage for an extended period of time: Causes overheating in motors.
· Over-voltage – Increased voltage for an extended period of time: Causes light bulbs to burnout.
· Line noise – Distortions superimposed on the power waveform: Causes electromagnetic interference.
· Frequency variation – Deviation from the nominal frequency (50 or 60 Hz): Causes motors to increase or decrease speed and line-driven clocks and timing devices to gain or lose time.
· Switching transient – Instantaneous undervoltage (notch) in the range of milliseconds to seconds: May cause erratic behavior in some equipment, memory loss, data error, data loss and component stress.
· Harmonic distortion – Multiples of power frequency superimposed on the power waveform: Causes excess heating in wiring and fuses.