As the name suggests, it is a power source that is a backup to your mains alternating current (AC) supply from the electricity board. Whenever there is a mains supply failure or outage, the backup source supplies power to connected electrical and electronic items, devices, or equipment.
Your MacBook or laptop running on battery when you remove the power chord is a common example of what we mean by backup power.
Generator Backup Power
Recognize diesel gensets? Yes, the ones you see everywhere these days — in industries, shopping malls, office buildings, residential complexes, etc. They are backup power sources. Specifically, diesel is the source of backup power.
The generator is an electromechanical equipment that converts the chemical energy of diesel fuel into mechanical energy through combustion and then uses the mechanical energy to rotate a crank, which produces alternating current (AC).
Battery Backup Power
There are at least four reasons why the diesel genset is not an attractive backup power option. First, thanks to its internal combustion, it is a source of air pollution. Have you seen smoke belching out of the chutes atop gensets?
Second, because of mechanical components, it is also a source of noise pollution. You must have felt the awful sound when getting into your building elevator after a power cut and the genset kickstarts and powers the elevator.
Third, the genset takes a few minutes to deliver a stable output AC voltage. The delay is unacceptable to most electronics such as Smart TVs, cable boxes, routers, and computers, which will experience a shutdown and reboot.
Fourth, it occupies a large space. Did you notice how the genset in your parking garage takes up valuable space? They definitely cannot fit inside the four walls of your home or office space.
Enter battery backup power! An inverter or a UPS inverting DC supply from a single battery or a bank of batteries into an AC supply overcomes all of the above shortcomings.
Do We Have a Winner?
Perhaps the single most reason the inverter or UPS is a preferred backup source over the diesel genset is the instantaneous supply of AC power. Within microseconds, power is restored to the connected electrical and electronic items, devices, or equipment.