Generators and switch mode power supplies.

buying a standby generator. One marketing point of

electronics' with computers given as an example. This

output.

actually going to care what waveform they see - from

Well, usually switcher has a full-wave rectifier and a smoothing cap at the input. This means it probably works fine even with DC voltage. The PC and similar stuff should be happy.

Stuff that runs through transformers may not like square wave.

You could run it through a good UPS (the kind that rectifies and re-generates AC) to get good regulation and waveform.

M

if you have store that sells the scorpian range theres a new type of genset, thay are the permanant magnet pure sinewave range, thay will run anything.

i have one of these its a 6.8kva model PM6500LX thay have no electronics in them to go wrong no brushes no caps no inverters.

Inverter type generators are sensitive to load surges. They are not as good as a regular generator in this respect. They usually turn off under heavy load, whereas a field excited generator will happily put out as much as it can.

However, inverter generators are fuel efficient. And the Honda series can be pararelled. If properly sized to the load/starting load then it should be fine.

Cheers

I fried a notebook power supply on a modified since wave inverter. I won't run any electronics on those beasts again. However, I don't know the mechanism of why the modified sine inverter fried the power supply. Given how a switching supply works, I didn't consider feeding a switcher with a cheap inverter to be a problem, but reality was different. Well, it was only a $100 lesson. It the notebook got fried, I think I would have been a little more POd. If I had to run electronics on a generator, it would be with one of those inverter generators.

The other advantage to the inverter generators is they worked on making them quiet.

Incidentally, generators are pretty easy to get used. People buy them for a particular lifestyle (say camping in the outback), then circumstances change (a newborn in the family keeps them at home, etc.).

"Sylvia Else"

** Pure marketing hype.

** All generators provide a reasonable sine wave.

But some do not have a steady or accurate frequency.

** No *generator* ever puts out a square wave or modified square wave.

You are BARKING up the wrong tree BITCH.

..... Phil

A few considerations:

1) Many inverters do NOT isolate; a relay drops out when the power failes, and that turns on the inverter. 2) AFAIK there are NO sine wave inverters, the best are pseudo-sine wave and even that waveform is not suitable to some equipment - which might be damaged. 3) A PC could run off of (roughly) 240VDC, BUT a number of monitors need AC. 4) Then there are all of those accessories running from....wall warts; more AC needed. Those last 2 items mentioned may be waveform sensitive...

AC.

You can get -48V supplies for PCs, rather than run of AC. I don't think I ever saw a PC supply that did both AC and DC, but that would be a nice product.

is the first google hit.

Really? Well, I suppose it depends on your definition of "reasonable". How about this one?

I dare say few devices would be upset by that, but it's clearly nothing like a pure sinewave.

Did I say that it did? Don't think so.

Sylvia.

"Sillier than Anyone Else"

** Totally irrelevant.

A " cyclo-converter " is also NOT a generator.

You pig ignorant TROLL !!!

...... Phil

I was thinking specifically of the inverter based generators, which have engine speeds that vary with load, but which maintain a constant frequency and voltage. I presume they rectify the AC output from the generator proper (or use a DC generator) then synthesise some approximation to a sinewave in the same way that a battery input inverter would.

I found this page discussing a Yamaha inverter based generator. It includes oscilloscope traces of the output, which is clearly a pretty good sinewave. I haven't been able to find any indication of the technology used for this (unless it's the obvious method involving filtering).

Sylvia.

What is a "generator" Phil? A device that generates? The Honda device chugs away happily (I assume) generating power. The cycloconverter is part of the mechanism.

Sylvia.

Not really. A computer doesn't care much as long as the voltage is within range. One thing to consider is that computers are a bad load to a generator. As a rule of thumb you need a generator with at least twice the VA rating as the total VA rating of all computers. Otherwise the generator cannot keeps its rpm constant (starts speeding up and slowing down).

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
                     "If it doesn\'t fit, use a bigger hammer!"
--------------------------------------------------------------

"Sillier than Anyone Else"

** In the CONTEXT where I used the word - it referred to a small, petrol motor driven, single phase alternator.

You pig ignorant TROLL.

..... Phil

That'd be right. Change the context without notice.

Sylvia.

My classic GE SCR manual (5e, gala 15th anniversary edition, 1972) has a section on Cycloconverters. It's basically a phase controlled switcher that converts a high frequency sine wave into a lower frequency one with a fairly ratty waveform. I could post it if there were great demand.

The Honda generators seem to like to put power electronics between the generator and the load, either a rectifier/inverter or a cycloconverter. Makes sense.

John

I assume that's related to the harmonic load represented by switch mode power supplies.

Circuits for significantly improving the harmonic performance have been around for a decade, but I suppose little will happen until legislation requires their use.

Sylvia.

I assume that was referring to the variation in power consumption between busy and idle.

EU legislation has required their use for some time (2001, AFAICT). Specifically, most power supplies above 75W must comply with IEC/EN61000-3-2, with computer PSUs conforming to class D.

In practice, this means that a typical ATX PSU starts with a boost converter whose current waveform is roughly sinusoidal, and in phase with the line voltage.

Although this isn't required in the US, I would assume that most PSUs will have been designed to meet EU standards anyhow (cf RoHS).

FWIW, an application note on PFC:

May not have happened yet down there, but has been around for about 2 decades in the US now.

Power factor correction and harmonic suppression are two different things. It is just convenient that typical PFC circuits also reduce harmonics.