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Quick question: can I damage the PT if the primary is connected to mains but nothing has been wired up on the secondary side? I'd like to measure the true secondary voltages before continuing with the build but I'm not sure if a PT with no load connected might suffer from overheating & damage in the primary coil.
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Without a load on the secondary, the primary isn't really being tasked with anything.
So it is o/k to power up the transformer unloaded. -
Thanks JPB. I guess measured voltages will also drop a little when it is wired up?Comment
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Yes they will.
That is the very nature of a transformer.Comment
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Thanks again. PT is a Hammond 372BX. Spec is 300-0-300 but manual seems to suggest it could be up to 323-0-323 which would require some rethinking of the circuit. I'll post what I get for reference.Comment
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The "true" secondary voltage is what it puts out into it's rated load, unloaded voltages are just for rough calculations.
Some transformers are spec'd at what rectified DC will be obtained from them, I seem to recall someone saying Hammond may do this in places, but I'm not sure about that.
Maybe you can upload the spec sheet here.Originally posted by Enzo
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So according to those specs, your secondary will be 300-0-300AC when delivering 115mA.
And that is with 120V input, so yes, with higher primary (125VAC where I am), and lower current off the secondary you could find your secondary climbing to the 323V you mentioned.Originally posted by Enzo
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