True sine wave generators

[Dave_Snelson]

I am about to buy a gennie. I am wondering whether to go for a Kipor true sine wave or get something more powerful and much cheaper, but not true sine wave.

I do not intend running a computer or similar equipment, just say, microwave oven, wall heaters and lights.

What doest thou think o learned gennie users?

 

[DAKA]

I bought a Kippor IG 2700.
They are much lighter and easy to handle than the old type.
give 2600 watts continuous
and 2700 max

about 30 kg I think, 4 stroke, main difference is they can charge your batteries without damaging your charger.

£365

 

[Garryt]

I also had a Kipor genny on my last boat and it was faultless. At the time, it was made from about 95% Honda bits, but apparently Honda stopped them selling those models at the time.

It was very quiet and adjusted the revs depending on the load. The quietness of the genny was one of the most important things!

Mine was about 2.3KVA I think.

 

[nimbusgb]

Some microwaves are more tolerant of non sine wave feeds than others. Usually a problem with inverters rather than gen sets though. You shouldn't have a problem going for the bigger cheaper one.

 

[Dave_Snelson]

Hmm yes..quietness. Good point. I think the bigger cheaper ones are for building sites and therefore won't be as silenced as the Kipor.

 

[Garryt]

Friend of mine who's a raggie, has a rather large petrol genny. Amazing value for money, but quite hefty to move around and certainly much noisier than a suitcase genny!

 

[sailorman]

not all Mod sine waves will run the mocrowave

 

[jfm]

I think you're all at crossed purposes. If you mean a gennie with a rotating diesel/petrol engine, then at a constant RPM it will always by definition produce a PERFECT sine wave. That's the whole point, becuase if it is rotating at fixed rpm it is mimicing the sine wave produced by the generators in land power stations.

So I'm completely perplexed that you have found generators "more powerful and much cheaper, but not true sine wave". Can you post a link plse? I'd love to see how a gen can make non perfect sine wave

If you're buying an inverter then it's all different. They run on DC so there is no sine wave, and they have to create the sinewave electronically, and often do so at an approximate level only, hence the concept of true and untrue sine waves from inverters

 

[Wiggo]

I could well be wrong (I often am), but I understand that the cheaper gennies use an alternator/rectifier and inverter rather than generating 240V AC directly. The reason for this is that it removes the need for fine control of motor speed to maintain the output frequency.

 

[Dave_Snelson]

Spot on - and whats more the height - and therefore the voltage - of the wave is "clipped" so you don't get a curved peak. You get a flat top with harsh spike on one edge, more like a gone-wrong square wave, still at 50 Hz though. This does electronic equipment no good at all.

 

[Dave_Snelson]

Not the case unfortunately, see my response to Wiggo!

 

[Steveu]

You get a flat top with harsh spike on one edge, more like a gone-wrong square wave, still at 50 Hz though. This does electronic equipment no good at all.

I don't understand why electronics would dislike this ropey waveform since they pretty much all have switch mode power supplies which just take a big bite out of the middle of the incoming mains waveform anyway....I would have thought that only the older linear PSUs would be fazed by that....is there something I haven't taken account of, Dave?

 

[MapisM]

Mmmm...
I fail to understand the difference between what you and jfm are saying.
Particularly if you pay attention to the first and last IFs in his post...

 

[No Regrets]

I have a Honda 2KW, and it works things beautifully.

Sensitive things seem to work via transformers anyway, so once the Genny power has passed through an inveter, and the transformer has done it's stuff, the equipment will be unharmed.... /forums/images/graemlins/grin.gif

 

[Garryt]

Here's an extract from an article:

-------------------------------------------------------
Generator Types

For the purpose of this article we will focus on the 2 main types of generator in use for the home, traveller, tradesman, etc.

The 2 types are commonly referred to a square wave (otherwise known as modified sine wave) and Inverter or sine wave. This relates to the quality of power they output. The cheaper type of generator is the square wave, which often looks like the skid style while the more expensive type of generator is the sine wave or inverter generator.
What the heck is a sine wave or a square wave?

Power generated by the electricity authorities is known as alternating current or AC, which consists of 240 volts and a frequency of 50 hertz, which means it cycles in a sine wave form 50 times a second. One complete sine wave starts at a zero point then rises to a positive peak and drops to a negative peak before returning to zero. The diagram below show the difference as they appear on a device called an oscilloscope.
Sine wave

A square wave generator is fine for running electric motors in things like pumps, fridges, air compressors etc. But they can damage electronic equipment like computers, TV’s, microwave ovens, fax machines etc. this is because the electronic equipment is extremely sensitive to the wave form.

A good quality pure sine wave generator is then the answer, which is why it is so popular with travellers and home/office users as a reliable source of power.

Another advantage of sine wave generators is that they are generally much quieter.
-------------------------------------------------------------------

 

[Nigelhg]

Some of the cheaper generators are actually DC generators with an inverter built in. This makes up the most of the suitcase type. The cheaper ones use a modified sine inverter, the better ones use a pure sine inverter. Cheap generators like that ones some of the discount chains sell put out a very poor sine wave and are poorly regulated so are unsuitable for use with sensitive electronics. Hope this helps explain things.

Nigel

 

[dhobyb]

and just to complicate things some more, modern electronic equipment uses "Switched mode power supplies" to convert AC to DC, (which is why you can use inverters safely) the older transformer based power supplies need a smooth AC sine wave supply, at a contant voltage, whereas the Switched mode ones do not. Those of you who are interested in such things will have noticed that your Laptop power supply input voltage range is 100v to 240v. So the upshot is that modern power supply equipment does not need a smooth perfect AC supply. However if you do use the cheaper generators then you could end up with noise problems, but that is another story.

 

[Dave_Snelson]

Thats as much as I know Steve. Maybe the spike (which to anything) is seen as much higher than can be handled by the solid state devise that handles it. I know that PC's and their associated power supplies don't like anything other than true sinusoidal waveforms - ditto some micrwave ovens. I don't want to risk this coz a good PC is much more expensive than a small gennie, so I have ordered the Kipor to be on the safe side!

 

[Dave_Snelson]

Thanks Dhoby. You actually prompted me to do the sad thing and look it all up on Wikipedia. It appears that through capacitance or EMI, there can be risks to equipment albeit the risks are low.

I was going to cut and paste the article here but then thought better of it as I think we've done the gennie thing to death now /forums/images/graemlins/wink.gif

 

[jfm]

[ QUOTE ]
Here's an extract from an article:

-------------------------------------------------------
Generator Types

For the purpose of this article we will focus on the 2 main types of generator in use for the home, traveller, tradesman, etc.

The 2 types are commonly referred to a square wave (otherwise known as modified sine wave) and Inverter or sine wave. This relates to the quality of power they output. The cheaper type of generator is the square wave, which often looks like the skid style while the more expensive type of generator is the sine wave or inverter generator.
What the heck is a sine wave or a square wave?

Power generated by the electricity authorities is known as alternating current or AC, which consists of 240 volts and a frequency of 50 hertz, which means it cycles in a sine wave form 50 times a second. One complete sine wave starts at a zero point then rises to a positive peak and drops to a negative peak before returning to zero. The diagram below show the difference as they appear on a device called an oscilloscope.
Sine wave

A square wave generator is fine for running electric motors in things like pumps, fridges, air compressors etc. But they can damage electronic equipment like computers, TV’s, microwave ovens, fax machines etc. this is because the electronic equipment is extremely sensitive to the wave form.

A good quality pure sine wave generator is then the answer, which is why it is so popular with travellers and home/office users as a reliable source of power.

Another advantage of sine wave generators is that they are generally much quieter.
-------------------------------------------------------------------

[/ QUOTE ]

I could be wrong but it reads to me like the author of that is talking about inverters, not generators. I dont think combustion engined sine wave generators are "popular with travellers " due to the fact a diesel engine wont fit in a briefcase