WHAT IS THE Difference between an inverter and UPS?

The difference's between an inverter and a UPS are as follows

1) CHANGE OVER TIME: An off-line ups (the standard) switches to the batteries in 3 to 8 milliseconds, after the main power has been lost.
The typical Inverter changes over in about 500 milliseconds

2) SIZE: Off-line UPS's go up to about 2kVA
Inverters go to 16kVA, 3 phase(what i could find browsing)

3)VOLTAGE REGULATION: UPS's have automatic voltage regulation (AVR) set on average at 220v
Inverters output voltage is the same as the mains input voltage (South Africa = 230V)


An inverter can transform a voltage from say 12volts dc and up to 230v AC.
UPS means Uninterrupted Power Supply. If you use an UPS between your computer, and your socket in the wall, and experience a power failure, the UPS will act as a battery and give you some extra minutes work time to save your work, and turn of the machine properly. Without the UPS your machine would die immediately.
*note: the UPS is NOT a normal battery, so you cant put a battery between your computer and the mains.



2) The basic

difference in layman's terms is:

While both provide backup power during mains outage, with the UPS the switch is instantaneous whereas with the Inverter there is a gap of a second or two. This gap is OK for household gadgets such as lights, fans, fridge, etc. but not OK for computers.

In technical terms:

UPS: The mains power comes to the UPS. The AC is converted to DC and this DC is constantly charging the battery. The output of the battery is fed to the Sine wave inverter and it converts DC to AC and this feeds the equipment. Since power out is always drawn from the battery, there is no time lag when mains switches off; it just stops the battery from being charged and the UPS continues to supply power till the battery runs out.

Inverter: The mains powercomes to the Inverter. This is directly sent to the output but the AC is also converted to DC and this DC is constantly charging the battery. A sensor and relay mechanism checks whether the mains is ON or OFF. When the main switches OFF, the relay actuator triggers to switch from mains to inverter. Rest is same like the UPS. Because of this sensor and relay, there is a gap between triggering.

UPS involves more costly circuits and is therefore more expensive to make and sell.

Apart from these there is another difference. The AC supply has a pure sine wave whereas in an offline UPS the output is a near sine wav, not a pure sine wav where as for a inverter its step wave. This is the reason that we hear a hum when we attach a inductive load to a UPS or a inverter but we do not hear anything when its on AC supply.