low voltage transformer


Postby ma876 » Wed Oct 10, 2007 7:03 pm

hi this might seem like a silly question but what does VA stand for on transformers? I`m guessing its the output rating, if so what would a 150va transformer discharge in the form of amps, watts?
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Postby kbrownie » Thu Oct 11, 2007 7:14 am

HI ma876,
VA stands for the maxmium Volt Amp Rating This is the sum of Volts X Amps
so say that your mains voltage was 230V then the current would be 0.652A. (230x0.652=150VA)
Regards
KB
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Postby ma876 » Thu Oct 11, 2007 9:55 pm

thanks kb, how would i work out how many 20w lamps i could run from a 150va transformer?
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Postby sparx » Fri Oct 12, 2007 9:38 pm

seven!
150 divided by 20 = 7.5 & as you can't buy half a lamp it's 7 with a bit to spare!,
VA is as KB says Volts X amps = watts for a purely resistive load, if inductive such as motors transformers ect, then power factor reduces actual power available which is why gen. sets have 2 ratings watts & VA.
Makers always advertise in VA as numbers more impressive, a bit like Americam horse power, only pony power to our way of measuring!!!
regards SPARX
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Postby ma876 » Sat Oct 13, 2007 3:53 pm

Thanx very much
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