Hi Jim ¨C While in most transformers it is minimal, the primary resistance also draws current, so it is the sum of the two for total. Actually, the R might dampen the input surge some. Remember, at T equal to zero, only the R is present as the inductance is an open circuit until magnetization takes place. 73 ¨C Mike
From:[email protected] <[email protected]> On Behalf Of Jim Whartenby via groups.io Sent: Sunday, August 11, 2024 1:17 AM To:[email protected] Subject: Re: [HallicraftersRadios] HT-37 transformer failure due to rapid STBY-->OFF-->STBY
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Don
Most , if not all, power transformers we use in radios are close to half a volt-per-turn in any winding, primary or secondary.? 240 turns would be about right for a 120 volt primary.? Since the transformer secondaries are all open circuit, the only power drawn form the AC line is what is needed to generate the magnetic lines of force aka flux in the transformer's core.??
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This changing flux generated by the primary winding also cuts the primary winding in such a way to generate a voltage to oppose the AC line voltage aka a counter EMF.? So in the end, only a miniscule current flows from the AC line through the primary winding.? Just enough line current flows to support the flux needed to generate the counter EMF and account for the power losses in copper and iron.? This counter EMF is in anything with a winding which gets it power form the AC line: transformers, relays, motors, inductors, whatever.
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It should be easy for you to verify the turns-per-volt of any power transformer.? All one needs is some thin magnet wire to wind around the core and something to measure the resulting voltage.? Note, you can have nothing smaller then a half turn coil.? Like what is used in a Weller soldering gun heating element winding.
