What is Kpa capacity?

[RogerChev]

Hello all, newby here.
I have had a 3 phase supply fitted some time ago and I have just tried to have it metered, but I am being asked to supply the following info,
1, what is the KPa capacity?
2, is it a whole current supply?
3, are current transformers being used?
4, if so what are the CT ratio's

How can I find out all this info, any help would be much appreciated.

 

[EFLImpudence]

You must mean kVA - the maximum demand.
kilo/volt/amps x power factor = watts

http://www.diynot.com/forums/viewtopic.php?t=186494
http://electronics.stackexchange.com/questions/19666/whole-current-meter

Current Transformer - A transformer used to measure the amount of current flowing in a circuit by sending a lower representative current to a measuring device such as a meter.

Current Transformer Ratio - 1) The ratio of primary amps divided by secondary amps. 2) The current ratio provided by the windings of the CT. For example, a CT that is rated to carry 200 Amps in the primary and 5 Amps in the secondary, would have a CT ratio of 200 to 5 or 40:1.


Google is good.

 

[AdrianUK]

You must mean kVA - the maximum demand.
kilo/volt/amps = watts x power factor..

Nearly.....

Watts = KVA * pf

KVA is known as the 'Apparent Power' and is the product of volts * amps

Watts is real power, or 'work done'

KVA is always bigger, unless the pf is unity in which case they are the same.

 

[RogerChev]

Yes my mistake, it is KVa. Is that something I could work out for myself or do I need an expert?

 

[EFLImpudence]

D'oh, thanks.

 

[RogerChev]

Agreed silly reply, sorry. No insult intended.

 

[EFLImpudence]

No, I was replying to Adrian for pointing out my silly mistake.

 

[EFLImpudence]

What is the supply for?
Shop, Garage?

What are you going to be running?

 

[RogerChev]

So can I simply go to an electrician to get this information, or do I need a special electrician, as I don't seem able to find one locally. All I want is to have a meter fitted..

 

[RogerChev]

it's for a hair & beauty salon and 3 sunbeds

 

[flameport]

The information you require can be obtained from whoever designed the electrical installation you intend to connect this new supply to.

 

[plugwash]

You should be able to make a reasonable estimate yourself.

Look up the ratings plates or manuals for any high power equipment (sunbeds, electric showers etc), if they quote amps multiply it by 230V to get VA if they quote watts and power factor divide watts by power factor. If they only quote watts divide it by 1 for resistive heating equipment (including showers) and 0.8 for anything else.

Once you have kVA numebrs for all the high power equipment add up the highest power combination that is likely to be used at the same time. Add 5kVA or so for incidentals (lighting, portable applicances etc). Add a reasonable safety margin (25% is probablly fairly reasonable if you don't anticipate any growth) since you don't want to be paying for an upgrade soon after your supply is put in if you misestimated.

And you have your number.

edit: fix screwup pointed out by efl

 

[EFLImpudence]

if they quote watts and power factor multiply watts by power factor. If they only quote watts multiply it by 1 for resistive heating equipment (including showers) and 0.8 for anything else.

Now you've done the same as I did.

VA = Watts divided by Power Factor.

 

[JohnW2]

You should be able to make a reasonable estimate yourself. ... Look up the ratings plates or manuals for any high power equipment ... Once you have kVA numebrs for all the high power equipment add up the highest power combination that is likely to be used at the same time. Add 5kVA or so ... And you have your number. ...

You're talking about the demand. The OP has been asked about the "KVA capacity" of the supply - isn't that a question which on;y the DNO who installed the supply could answer (we've been told that the supply was installed some time ago)?

[ Can someone tell me what a "whole current supply" is (which the OP has also been asked about)? Do they perhaps simply mean 'whole current metering' (as opposed to CT metering? ]

Kind Regards, John

 

[mfarrow]

If the fuses on the supply cutout look like ones at home then I doubt you have CTs. The CTs will be for larger supplies where the DNO fitted a whopping big box about 3' tall.

In which case I think John's right and these are DNO questions. I've not done one in a while but I think the origin point is typically the DNO, who pass the workflow information through to your chosen supplier. I'm not sure why your supply was left without a supplier. Was the job halted at all for some reason?

In any case I suggest talking to the DNO first, say you have a new supply and an elected supplier, and will they please tell you the process. I certainly think you should NOT be passing information yourself between one and the other, and I would push back on that. It's potentially dangerous and is liable to be open to abuse, especially where CT ratios are involved!