Generator Ratings KVA or Watts

Submitted: Monday, Jun 04, 2012 at 13:10

ThreadID: 96010 Views:2538 Replies:5 FollowUps:5

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The generator, which was discovered by Michael Faraday, is an ingenious device that converts mechanical energy into electrical energy.

Member - lyndon NT

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Just wondering what the more learned than I think of the way generators are being advertised. Normally I would have expected a listing of output in KVA, not in Watts as the manufacturer doesn't know whether you will plug in a resistive or inductive load. Could this be seen as misleading advertising? Maybe the guru's like Robin would like to comment?

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Reply By: Member - lyndon NT - Monday, Jun 04, 2012 at 13:11

Monday, Jun 04, 2012 at 13:11

I have no idea of why the link ended up at the top of the page when I put it in the middle?

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Reply By: Member - Bruce C (NSW) - Monday, Jun 04, 2012 at 14:56

Monday, Jun 04, 2012 at 14:56

Hi Lyndon,

This business of quoting KVA is causing confusion, as you have experienced.
The best way to measure for the likes of us is WATTS.

The advertisers use KVA because it is a bigger number than Watts so people think they are getting something better than they realy are.

When looking, go by the watts and you can't go wrong in my experience.

Cheers, Bruce.

PS. seems there is a problem with your link.

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Follow Up By: Member - lyndon NT - Monday, Jun 04, 2012 at 15:17

Monday, Jun 04, 2012 at 15:17

LINK

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Follow Up By: Member - lyndon NT - Monday, Jun 04, 2012 at 15:23

Monday, Jun 04, 2012 at 15:23

Hi Bruce

New link is working ok for me. I don't think Advertisers use KVA because it sounds bigger, Volts x Amps, is potential power. Watts is actual power. In a resistive circuit you may get close to unity but with an inductive load (i.e, airconditioner), the power factor will come into play, current lagging the voltage. So if your airconditioner had a P.F of .85 using VA this would give you 1700 Watts of power.
Interested what others have to say.

Cheers

Lyndon

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Follow Up By: Member - Bruce C (NSW) - Monday, Jun 04, 2012 at 17:33

Monday, Jun 04, 2012 at 17:33

Lyndon, I just ran my cursor over the link and it came up with a preview thumbnail showing "Error 404 Page not found" so I did not go further.
I just tried it and as you say, it works OK.

Re KVA versus Watts I find in most of the adds for generators on ebay, and I don't doubt on other sites as well, that we are attracted by the claims of high KVA output but when you drill down into the specs we find that its watts ays much less.
EG A genny advertised as 3300KVA is very often shown in the specs as being capable of producing only 2700 watts, these figures are not precise, I am picking figures out of the blue. But if you check it out you will see that I am close to the money on those figures quoted. This is why I say they mostly quote the larger figure to get the punters looking, so to speak. It has caught me out many times.

Watts is the real world figure we lay people need to think about when considering a genny, from my limited experience in electrics.

Cheers, Bruce.

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Reply By: Racey - Monday, Jun 04, 2012 at 15:37

Monday, Jun 04, 2012 at 15:37

Hi lyndon NT,

Your question roused my curiosity as I have often had doubts about some of the ratings quoted by various manufacturers. Some are Watts including Honda and Kipor, some are KVA like Yamaha. A quick phone call to Genquip confirmed that the 3300 Watts rating was also 3.3 KVA. How is this possible you may ask; simple, you quote a power factor of 1. The concept may be technically correct. However, I have searched all the published and cannot find any reference to the rated power factor at rated or Maximum capacity. Most industrial generators are rated KVA with Watts or KW based upon a power factor of 0.8. Therefore, if the Genquip 3300 is in fact 3.3 KVA then the rating in watts would be 2640 watts.

There is a little bit of smoke and mirrors going on and I suspect most if not all the portable generators rated in Watts would be the same.

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Racey

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Reply By: Member - Fred B (NT) - Monday, Jun 04, 2012 at 16:00

Monday, Jun 04, 2012 at 16:00

Lyndon,
just to add a little more confusion to the issue.....
MOST DO NOT HAVE A CONTINUOUS RATING
Example... if you were to buy a generator stated at 2kva or 2000W, the vast majority of those gensets would find it impossible to run at max load and more important, maintain a load of 2000W even if the power factor was 1.
So the general rule is that your max load will be 2000x0.85=1700W
A good genset such as the Honda20ei will carry that no problem, cheaper models will probably only be able to maintain a continuous load of approx. 85% of the 1700W = 1445W with short periods of load at 1700W.
Hope this helps.
regards

Fred B
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Follow Up By: Member - lyndon NT - Tuesday, Jun 05, 2012 at 07:55

Tuesday, Jun 05, 2012 at 07:55

Cheers Fred. I still feel by putting the rating in Watts it will catch a lot of people out when trying to run certain appliances.
We still owe you that Barra :-) In 2010 on our annual fishing trip we got caught by Cyclone Paul in the Gulf and narrowly missed get traped, 2011 saw the Roper still in flood, hundreds of HUGE prawns but no fish! Couldn't get away this year. So a parcel of fish is coming you way SOMETIME in the next couple of years. :-)

Cheers Lyndon

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Follow Up By: Racey - Tuesday, Jun 05, 2012 at 09:09

Tuesday, Jun 05, 2012 at 09:09

Fred, You were close, the Honda 20ie is rated 1600 watts. I also double checked the Yami 2400. It's rated 2KVA, 2.4KVA Max. As I said in my earlier post there's alot of smoke and mirrors in these ratings.

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Reply By: Cravenhaven - Tuesday, Jun 05, 2012 at 09:41

Tuesday, Jun 05, 2012 at 09:41

Well in my view the ratings should be quoted in KVA, but a lot of people dont know what that means so the manufacturers use watts instead.

If you are looking for a Genny and want to power your microwave and electric frypan or stove/oven etc, all the ratings for those appliances are in watts. So your selection of the right sized Genny would be based on the sum of the appliances to be used concurrently. They could use KVA when creating the rating plate for those appliances because they are mostly resistive devices, but then consumers wouldnt know what it meant.

In any case, why should a manufacturer ASSUME that their customer is going to use a motorised device on the genny and consequently derate their equipment by guessing what the power factor might get to?.

cravenhaven

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