Power Outage

Power Outage is the loss of electric power in an area for a short period or long period. It is generally known as Power failure, Power cut or Black out. Power outage is critical in places like Hospitals, Mines, etc where public safety is at risk. So in these sites, alternate power sources like generators or inverters are used to provide uninterrupted power supply. Some important causes of Power Outage include faults in the power station, short circuit, or damage in the transmission lines or the distribution system.

The Power outage is caused mainly by three reasons. These are:

  1. Transient Power Outage – This is the momentary power failure usually lasting a few seconds. Transient power outage may be due to tree contact, animal contacts in the power lines or due to lightning.

  1. Brown out – This is the voltage drop in the power lines. The term Brown out is introduced since the low voltage causes bulbs to dim. Brown out is a very serious condition which can cause poor performance of electrical or electronic equipments or it may permanently damage them. The important effects of brown out are :
  1. Brown Out can cause heating of Motors, Compressors in AC or Fridge. Low voltage also increases the current consumption in these devices to compensate the decreased voltage. Incandescent bulbs generate much heat in low voltage.
  2. The mechanical power of Motors will run at low speed and torque in Brown out conditions. Motor will draw more current due to reduced back e.m.f develops at low armature speed. This may result in permanent damage of the armature by burn out.
  3.  In CRT monitors, brown out causes shrinking of screen size, dimming etc.
  4. In DC power supply, brown out causes the appearance of ripples at the output.
  5. In digital circuits, brown out brings the control signals below the threshold at which the logic state is detected. When the input voltage returns normal, the logic state sometimes latch and show incorrect states.
  6. In DC power supplies, the output voltage drops when the input voltage drops.
  1. Rolling Black Out

This is commonly called as Load shedding which is the intentionally doing power outage in areas to conserve power. In Rolling Black out, power supply is stopped for non overlapping periods and resume the power after the predetermined time. This done when the demands for the power exceeds the production or power distribution.


Power outage can cause many problems in electric and electronic devices which can be reduced by providing adequate protection systems. These includes, Spike protectors, ELCB, MCB, Surge breakers etc. In computer system, power outage affects data loss and hardware damage etc. So UPS is used in computer systems to avoid this.UPS provides well regulated output free from spikes and transients. If power fails or voltage drops, UPS will instantly takes over the system through back up.




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