Inverters Vs UPS
Why select an inverter or UPS – what is actually the difference?
Interesting question which no doubt baffles many people that really don’t give a hoot.
Having grown up through the 70s and 80s it was interesting to see how the old tried and tested circuits gave way to the new, failure riddled semiconductor switching circuits. Here I talk about switching even relative low voltages and currents, germanium transistors just didn’t like intolerance on the junction temperatures and of course even with silicon transistors, secondary breakdown would normally condemn the circuit to the scrap heap. I even had to once go to a TV shop in PE in the early 80s to buy high voltage rectifier diodes for the radar “static inverter” on the ship I was serving. This was a relatively new term but one needs to note that the older type inverters on marine vessels and aircraft used to be rotary converters.
Anyways, like them or despise them semiconductors changed the way we viewed voltage converters and through the years we noticed the size of switching power supplies getting smaller as the power output increased dramatically mainly caused by heavy transformers giving way to ferrite core, high frequency chopping circuits.
Well, so back to the drawing board. So in fact there is no difference between a UPS and inverter, they both use a switching circuit, it can be any architecture as long as when power goes off the device has an output which can power the device needing to be powered. We read about the switching time between mains to battery backup and yet if one looks at certain manufacturers, their designs are also very quick to changeover – indeed monitor any design used in a house, with solar panels etc, one won’t necessarily pickup the difference when on utility power or batteries, the power supply reservoir capacitors carries the load for the few milliseconds of switchover.
A UPS is an inverter with batteries (backup when grid or utility supply fails). We also have inverter generators – Your common and garden home variety 5kW genset has a very dodgy waveform at least, the inverter generator has been designed to power your sensitive electronic gear. The inverter will convert the dirty power into a great happy clean regulated sine wave.
UPS batteries are usually inside the cabinet, with an option of extended run time usually in a separate rack or cabinet – as time goes by and with the onset of renewable energy and frequent grid failure the two become one and the same thing – back up power from an inverter, solar and batteries. Combine them all and put into a trolley.