What we need is a demonstration, where you can see the effect of each of the different types of UPS. OK simple, what you need is an oscilloscope, some decoupling device, a variac, a multimeter. Oh, and of course one of each type of UPS.

Or you can have a look at this flash file on UPS operation. It’s cool!

UPS Operation Screenshot

There is only one advantage – price. A square wave system is the cheapest to produce. It requires the fewest, and cheapest components available.

When I first became involved with UPS I was astonished that square wave UPS even existed. I thought a UPS provides power when the lights go out – right? My assumption was that the power it would deliver would be equivalent, if not better than the power that was originally present. After all, as an educated electrical engineer, I knew that the mains power was a 50Hz sinewave waveform, so you would assume that a device that simulated the mains power would generate exactly the same? How wrong this assumption is. A square wave is a nasty waveform, in effect bombarding your equipment with a high frequency transient (the leading edge of the squarewave) of a voltage up to 300V 50 or 100 times per second. These transients have a damaging effect on all electrical circuitry.

So why use them?

Well, as power cuts are usually infrequent, the damaging effect of the UPS is limited. In addition, a typical PC will have a Switched Mode Power Supply (SMPS) that will appear to work fine with a square wave input. So for a home PC, for protection against infrequent power cuts, and only to prevent annoyance, rather than any critical data, a square wave system provides a cost-effective power protection solution.

A square wave system has its place, but only for non critical applications, and only for protection against infrequent short term power cuts, and then again, only for systems that have a SMPS. For anything other than this, you need to look at sinewave systems.

We’ve had more and more enquiries about shipping to the continent we’ve added many European countries to our shipping algorithm. We now have competitive rates to ship to many European countries on both box and pallet rates. A box rate is no more than 30Kg, and above this we will ship out on pallets. If a rate is not available contact us to quote you a specific rate.

Just to see how competitive we are, how about a KR3000, 3KVA Online UPS delivered to Germany for under £430!