Any Help On Sizing A Generator

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Posted

All

 

I am no electrician so would really value some advice on what size of generator to buy as a back up power source for my house.

 

I have a 3 bed with living room, kitchen and garage and would like to run 3 AC's, Lights and power sockets (15) in the event of a Brown Out.

 

I do not know how to calculate the KVA required so if anyone out there has any knowledge in this area and would be willing to share it I would be very grateful. Also what I can expect to pay and is it possible to have an Automatic transfer switch.

 

Appreciate any help and in return if you need to know the secrets of the universe such as how to keep a woman happy or where does the universe end I am happy to share with you.

 

Look forward to inputs.

 

Paul B

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Posted

Pray tell us all how to keep a woman happy...

Some very knowledgable guys on the forum will help. Perhaps would help if you detail size of your A/Cs and refs.

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 Paul I have sent a PM with some information, When it comes to Electric and Generators you need to be careful  :thumbsup:

good stuff and your House are at the mercy of the Correct input on Brownouts  :)

 

Jack :tiphat:

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A very approximate answer would be to add up the kW rating for each device, double the total and call that your kVA rating. Somewhere on each appliance there should be a plate showing the nominal rating in kW and maximum current draw in amps.

Unfortunately the ratio between kW and kVA varies according to the type of appliance. This ratio is known as the "Power Ratio". For purely resistive appliances (those that only generate heat, stoves, coffee makers and incandescent light bulbs for example) the KVA value is the same as the kW value. For everything else KVA will be higher, sometimes much higher.

A quick search on the Internet for kW to kVA conversion will through up sites that will do the calculations if you plug in the numbers you get from the plates n the appliances.

Your ac is going to be the bulk of your requirement. Cut back on that and you will save a lot.

Costs I can't really comment on.

Hope this helps feel free to ask for clarification.

Sent from my iPad using Tapatalk

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Posted

Sorry should have written power factor not power ratio

Sent from my iPad using Tapatalk

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Posted
Your ac is going to be the bulk of your requirement. Cut back on that and you will save a lot.

 

Am not an electrician, but know a fair but about owning and running generators.  A/c is your enemy - They draw alot!

Check out this worksheet:

http://www.briggsandstratton.com/us/en/generators/portable-generators/portable-generators-101/how-much-power-do-i-need?sort=home

 

A high quality generator will last you for many many years.  A cheap one will fail and it will fail when you really need it.

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Posted

We have a place here in Subic called American Hardware (next to the older Royal Duty Free) and they have some really good portable generators.  I have never bought anything from this place because the prices are so high, but they have really high quality imported goods of many kinds.  I had not been in there for a long time but I stopped in last night, and they have a lot of new stuff, and the store looks good.  I spoke to the (new?) owner and/or manager, and he said they just got in a big shipment last week and they are in the process of cleaning up the store.  It might be under new management so maybe the prices will get better.  I never see anybody buying so I'm not sure how they stay in business.

 

Most of the generators were Honda powered with a few Briggs & Stratton.  They had a really big one (I didn't see the KVA) with a big Honda engine for p80,000.  If I really needed a good whole house backup system, I might be willing to pay that much.  If you are interested, I can stop by and get some details on some of them.

 

HMR in the same area has a lot of big non-portable generators, and that might be what you need.

 

I'm not helping on the size needed, but I thought you might be interested in knowing this.

 

Here is Subic we have fairly reliable power so I have no immediate plans to buy one, but I might in the future.

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Posted (edited)
would really value some advice on what size of generator to buy

 

My opinion, (and therefore my advice) is that the cost of fuel and maintenance to run a generator that size is going to be much more than 100 pesos per hour (exact numbers will vary of course and may be double or triple that amount.)

 

A 6500 KW gas powered generator would be enough to power your basic devices and ONE aircon (up to about 3/4 horsepower) but even that would burn about a liter of fuel per hour.  (Edit with correction -  the Chinese 6.5 HP I used to use burned a 5 gallon can of gas in about 10 to 12 hours so its more like 2 liters per hour). With your additional air conditioners, depending on the size, you will likely need double or triple that size and that puts you into a diesel powered generator which needs frequent maintenance.

 

So what I would do, if brownouts were still a problem for me, would be to get a 1500 KW Honda generator which runs on very little gas and would run the ref, a fan, a light, the Internet modem, the TV (many don't realize it but modern TVs are a big current draw when you are running only a small generator) and the computer.  Everything else is superfluous anyway.

Edited by Dave Hounddriver
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Posted (edited)

I agree with the previous post of Dave Houndriver. Unless you suffer regular and prolonged brownouts I wouldn't bother trying to maintain an equivelent power supply to the main grid. It would be prohibitively expensive, both to buy and run. Here in Cagayan de Oro we have occasional brownouts, most lasting less than 30 minutes. More rarely we have ones lasting up to 4 hours. Our mindset is to power just one room to see us through. Fridges and freezers will be OK provided you dont open the doors too often. We get by very well using a home assembled UPS using a 1000 watt pure sine wave inverter running off a couple of 12v/100ah deep cycle batteries. That will easily power our LED tv, dvd or cable tv box, a couple of fans, the internet, and a couple of LED lights for a couple of hours if need be. For longer brownouts I have a Honda eu10i suitcase inverter genny which gives 900 watts max and 750 watts continuous. That will power all of the above and if neccessary the fridge freezer for an hour or so to maintain temperatures as needed. The Honda is very quiet, uses about half a litre an hour and regulates its speed to the demand, so with perhaps 300 watts or so, which is quite adequate for getting by with the essentials, is extremely quiet and ecomomical.

Ken

Edited by Huggybearman
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Posted
Honda eu10i

 

That looks like a nice compact unit.  Where did you buy it and how much?

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