Q & A of the Day - kVA conversion on single- and three-phase supply

BookmarkThis 15.02.2008
SELECT
 

Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This one, about kVA conversion information for single- and three-phase supplies, is answered by SELECT:

A distribution board - but what kVA conversion?
A distribution board - but what kVA conversion?
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Question: The electricity supplier is putting a new three-phase supply into a unit rated at 150 kVA (at the builder's request). I am struggling to find the correct calculation from kVA to amps to determine the tails size. The new distribution board will be three-phase, and neutral - I hope - on a Merlin Gerin board. Could you advise of the correct calculation? I am sure what I have been told by lecturers to clarify the situation is incorrect for single- and three-phase.

Answer: For most small installations, kW would equal kVA and could be inserted on the supply request form. On larger installations, where inductive and capactive loads are applied, we have to consider a power factor (PF), which is the true power divided by the apparent power - with a value of 0.9 being typical. For reference, the kVA value is the kW divided by the PF.

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http://www.voltimum.co.uk/consult.php?universe=consult.index.questions

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Midlothian, Scotland EH26 0SB
Tel: 0131 445 5577
Fax: 0131 445 5548
Email: admin@select.org.uk
Web: www.select.org.uk
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