Line Interactive/AVR feature in UPS

[Rumman]

Does a line interactive UPS or an UPS with AVR facility last longer then their counter parts (i.e. offline UPS, UPS with non AVR)?

 

2 options available to me-

1. Offline UPS (Non-AVR) UPS buy with higher VA. OR

2. Line interactive UPS (with AVR facility) but lower VA UPS.

 

Which to consider?

[mariushm]

You're focusing on the wrong things. 

 

Offline vs Line interactive is about how the inverter inside the UPS is used. 

In offline UPS when there's a power failure or too low / too high voltage (because it's non AVR) , the AC input is disconnected, and the inverter is started and the inverter takes power from battery and produces the AC voltage.  It takes some time for the inverter to start and produce the power required by the computer, usually at least 8-10ms.

 

Line interactive UPSes keeps the inverter running all the time, but works from AC input until there's an event which is outside the acceptable limits and then it switches to battery ... so the switch time is faster, usually within 4 ms. 

The AVR basically means the AC input voltage is monitored and there's some sort of auto transformer which regulates the output AC voltage within some limits (ex 200v AC - 260v AC is auto regulated to 230-240v AC)

 

The VA rating is important ... the power consumption of the devices you connect to a UPS should not exceed around 60-70% of that VA rating ... for example if you have a computer with RTX3090 that consumes 400-500 watts in total from mains while gaming, it would be best to get at least a 750VA UPS, preferably a 1000VA one, and you should exit the game to reduce power consumption as soon as you notice the power failure. 

 

Batteries will last a few years, depends on their quality and how often they're cycled (how often you lose power and discharge them). Depends on the design of the UPS as well ... does it use a single battery therefore pulling a lot of current from the battery when it has to produce the power to keep your devices working, or does it use 2 or 4 such batteries (as higher input voltage means less stress on the batteries when AC voltage is produced by inverter) 

 

It will also matter how the UPS is designed in the sense of thermal management - a cheap UPS may use a transformer designed to be cheap because they do the math and know the transformer can last for 5 years or so if it runs at 90c for 6-8 hours until the batteries recharge once a week or so... but they won't care that having a 90c transformer near the battery will heat it up and potentially degrade it over time. They treat batteries as consumable.

A more expensive UPS will use a better quality transformer and there's also  fans to take out the heat from the insides.

 

A regular computer power supply is supposed to work without AC input for at least 16ms, but majority can only do 10-12ms under significant load.

 

Figure out how much power what you connect to the UPS will consume, and multiply that by 1.5 and that should be your minimum VA rating. 

 

Note that if a computer has a 650w power supply, it doesn't mean it consumes 650 watts, most modern computers consume less than 100 watts in Windows, browsing Youtube, typing such messages in a forum. 

Even if you're using a CPU at 100%, a CPU by itself consumes at most 100-150 watts so with all the other components in a computer you won't consume more than 200 watts. 

When gaming it's another story ... depends on the video card ... a video card can consume anything between 30w and 350w depending on the model. The average 1080p video cards consume 125-200 watts just by themselves.