Electronics > Projects, Designs, and Technical Stuff

60Hz Transformer Core Loss

(1/5) > >>

Evan.Cornell:
I've got a 40VA 120VAC->24VAC transformer that pulls about 4W according to my KillAWatt when completely unloaded. Is this amount of transformer loss a reasonable value?

Benta:
Looks a bit high to me. A better estimation would be to measure temperature rise. The Killawatt thingys are not really accurate at very load loads.

WattsThat:
While I expect you've got some measurement error in the 4 watt number, 10% magnetizing current is not unreasonable for a low cost HVAC style transformer. That’s an assumption on my part since 40VA is not an industrial rating.

Why do you care? It’s not like you can save much energy with a better transformer, those things are designed down to a cost point with the minimum amount of copper and iron required and efficiency is low on the list of concerns.

Evan.Cornell:
I don't really care... power consumption isn't really relevant to the project, but I was more just curious. Thanks!

TimFox:
Does your KillAWatt measure power or just primary current?  All transformers have a finite magnetizing inductance, which pulls current (90 deg out of phase from voltage) from the source when the secondary is unloaded.  The actual core loss due to going round and round the hysteresis curve, eddy-current loss, and copper losses due to current through the windings are actual power.

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod