This is the time that the battery must support the load and is
also often called back-up or discharge time
A total loss of electrical power.
A low voltage condition over an extended period of time.
An ac power path around a UPS.
automatic bypass is controlled by a UPS and operated under
fault or overload conditions to maintain power to the
A manual bypass is a user switch on a UPS allowing a complete
electrical bypass of the unit, used when there is a total UPS
failure or when carrying out maintenance or repair without
shutting down the load. Some parts of the UPS – the input and
output terminations for example – may remain live.
service or maintenance bypass is a manual bypass allowing
complete isolation, maintenance, or removal of the UPS without
shutting down the load.
Common Mode Noise
Disturbances between the neutral and earth or grounding
conductors. Noise may result from injection into the neutral
or grounding wires, wiring faults, or overloaded power
Expressed as the ratio between the crest (peak or maximum)
value of a current to the root-mean-square (rms) value. A
square wave of current has a crest factor of one. A sine wave
has a crest factor of 1.414. Typical computer power supplies
draw current with a crest factor of between two and three.
The function of a circuit or system that maintains a current
within its prescribed limits. UPS systems have an electrical
current limit that regulates the output current to a value
within the UPS limits.