RE: inverters and generators

["Benfield, John" <john.benfield@xxxxxxx>]

>I'm thinking of buying either a generator or an inverter. My main
>concern is keeping the freezer going during a power cut. What size
>generator is best: the biggest I can afford? I thought I read
>somewhere you should aim to use only 50% load?

Firstly, if you are only concerned about the freezer, then look at getting
=
a
new one as there are some out there that will keep their temperature for
upto 24 hours in the event of a power cut. This solution is allot cheaper
and easy than getting backup power.

If you still want backup power then okay. Firstly you don't need an
inverter. They are only needed if you wish to convert battery power
(12v,24v,48v etc) into mains 230v. What you need is a generator and a
automatic mains failure (AMF) controller. The controller will sense the
lac=
k
of utility power and switch the generator on. This is will not prevent a
power cut in the house, there will be a period of a couple of minutes
whils=
t
the change over is completed. I'm not quite certain is if will get an other
cut when you switch back to mains power.

On the sizing side, you need to work out what you will want to run in a
power cut. Fridge and lights don't really take much power, however start
adding things like TV's and microwaves and it's significantly more. A
microwave might be rated at 1000w however on start-up they can draw
significantly more. You need to list all of the items, there normal running
load and (if available) the start-up load. Then try and workout what the
maximum number of these items you will have on during the power cut. Add
th=
e
number up and you get the minimum size of generator you need. Generators
ar=
e
best run hard (so I'm told), so don't over size too much.

Cheaper generators don't have any voltage regulation, so they might produce
230v with minimal load attached, however draw 16amps and they might reduce
to 200v. Bigger generators have automatic voltage control that will hold
th=
e
voltage within about 1.5% of 230v. Again it depends what you want to run.

Buy a new good quality diesel genny rated to about 10kva will cost around
the =A35,000 mark, the AMF controller probably around another =A3500. For
t=
his
amount of money you will get some form of acoustic canopy, however you
migh=
t
need to get a domestic quality silencer and the industrial ones can be a
bi=
t
noisy. The set should come with a large fuel tank that should okay for 10
hours of so.

There are many generator manufactures out there, Lister Petter and Kubota
are ones I know about and produce the goods. Both have sales and service
distributors around the country. You can also look at second hand try Eagle
Machinery (www.kw1.com) or Beta Generators (www.betagenerators.com) and
eve=
n
eBay.

If your on mains gas then one option that looks good is a gas power genset.
Last time I looked a couple of people where about to try and market them
fo=
r
the domestic market as AMF based machines. From memory try
www.justgenerators.co.uk.






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