Quote:
Originally Posted by kalee20
If you connect the transformer to a variable supply (with a voltmeter across the supply to be sure you're hitting it with full voltage) via a wattmeter, leaving the secondary completely open-circuit, the power drawn is virtuall all core (iron) losses. (The primary current is relatively low, and secondary currents are zero, so winding losses are negligible).
Then if you dump the voltmeter in parallel, but put an ammeter in series, and this time short-circuit the secondary, wind up the input till you see the normal loaded primary current drawn. This time the voltage is low, so the magnetism in the core is low and iron losses will be negligible. The figure on your wattmeter thus will be copper losses.
Add the two figures together to get total losses at full voltage and full load.
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Brings back memory of the power lab experiments at university. Im guessing the load would have been around 20mA. I think I may run the risk of accidental damage and also not sure what my watt meter will read down too. I assume I need to be measuring true power rather than VA