UPS and inverters are back up power supplies during main power outage. In our daily lives, we are heavily dependent upon appliances that run on electricity such as fans, lights, AC, fridge, and so on. Whenever there is a power cut, electricity supply to these appliances is cut off and they stop working. However, if you have a backup supply in the form of devices such as UPS and inverter or generator, you can ensure uninterrupted supply of power to appliances to be not bothered with power cuts. However, people remain confused with the difference between a UPS and an inverter. This article will highlight the differences between these two devices so that you can make better use knowing their features.

While both devices provide backup power during mains outage, the only difference is the time lag. While a UPS instantly starts supply, with an inverter there is a lag of around half a second which is unacceptable if the device is a computer that you are working upon. For the rest of the appliances, however, this time lag is acceptable and this is the reason UPS is used only for computers whereas inverters are used for all other household appliances.


The main power comes to the UPS and is used to charge a battery inside. The output from the battery is fed into a sine wave inverter which converts DC into AC and feeds to the computer in case of a power failure. In such a scenario, the battery is stopped from charging and instantly starts to supply power to the computer.

*CHANGE OVER TIME: An off-line ups (the standard) switches to the batteries in 3 to 8 milli seconds.


AC is converted into DC and then is used to charge the battery. When the power supply goes off, the relay triggers the switch from mains to inverter. It is the use of a sensor and a relay that is the main difference between a UPS and an inverter, otherwise the two are same. And the use of relay and sensor cause the time delay in power supply from an inverter.

*CHANGE OVER TIME: The typical Inverter changes over in about 500 milliseconds,which is suitable for Home appliances like TVs , Refridgerators but not for Computers which need immediate backup.Otherwise,they are going to restart!!

Difference between UPS and Inverters

The circuitry used in a UPS is costlier than that used in an inverter which is why UPS seem to be costly. Thus it is clear that UPS are small capacity inverters that also have the advantage of a smaller time lag which is why they are suitable for appliances such as a computer which will die off if you try to connect an inverter with it. One more advantage that UPS has over inverter is that it is free from any voltage fluctuations whereas inverter’s output voltage is always dependent upon input voltage. However, there are pure sine wave inverters available today that make the use of UPS redundant as they can supply uninterrupted power supply in the case of a power failure.

Posted By

M.Shiva Chaitanya(4/4 ECE) MGIT