In now a days shopkeepers are making fool of their customers by selling Inverters as UPS, usually layman dont know the difference between an Inverter and UPS therefore I have wrote a guide before buying a UPS.
Following are the difference between UPS and Inverter:
Change Over Time:
Usually a UPS switches to batteries during power failure within 3 to 8 milliseconds however a typical Inverter takes 300 to 800 milliseconds for switching. In now a days few inverters have less switching time and they advertise that they can run computers and televisions but it doesn’t mean that they are same as UPS always prefer UPS for computers and electronics stuff instead of Inverters.
Usually a UPS provides purified Sine-Wave output which is good for all kinds of electronics appliances, however an inverter provides square wave output which is good for general household like fan, tube-lights but not recommended for sensitive appliances like computers, televisions, mobile chargers etc…
UPS provides fixed 60Hz frequency which is required for sensitive equipments, however Inverter‘s frequency usually changes on battery condition and load.
PWM system is typically used in UPS so it provides fixed regulated output voltage regardless of battery condition and load however Inverter output decreases / increases as per load and battery condition. Sometimes inverter‘s output is so high that it burns sensitive equipment like computer or televisions.
Inverters can automatically switch / start themselves on electric failure but voltage controlling and sensing features are usually not available in Inverters thats why inverters are not good for sensitive equipment. UPS have built-in light speed switchover and other then that UPS senses voltage and if voltage drops from a certain limit it protects equpment by automatically switching to backup mode.
If you are planning to purchase power backup for fans and tube-lights you can go for a good quality inverter with automatic switch over and battery charger. However if you want complete solution for your computer, laptop , mobile chargers, fans, tubelights etc.. buy a UPS instead of Inverter .
In local Pakistani market inverters are boxed as UPS, locally manufactured un-branded UPS are not UPS in reality they are low quality automatic inverters with battery chargers marketed and boxed as UPS. Before purchasing UPS find a good quality brand and read specs and details about it. Always ask shopkeeper about PWM voltage regulation and voltage ranges.