Before the widespread use of power electronic equipment, microprocessors for industrial control, and automation in factories and offices, minor variations in power did not seriously affect the operation of conventional equipment such as lights and induction motors.
If the supply voltage dipped because of a fault (i.e., a sag in voltage occurred), the lights just dimmed, and the induction motor produced a lower output.
These days the effects of power interruptions are rather costly. Reference 10 lists the following cases to illustrate the cost of short-duration power interruptions:
a. One glass plant estimates that a five-cycle interruption, a momentary interruption less than a tenth of second, can cost about $200,000.
b. A major computer center reports that a 2-s interruption can cost some $600,000.
c. In some factories, following a voltage sag, the restarting of assembly lines may require clearing the lines of damaged work, restarting of boilers, and reprogramming automatic controls at a typical cost of $50,000 per incident.
d. One automaker estimated that total losses from momentary power interruptions at all its plants run to about $10 million a year.
Power disturbance and power quality issue is costly. Learn more about power quality on this site.
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