Transformer current phasing

Thread Starter


Joined Sep 7, 2009
The transformer phasing pages states that voltage and current are in-phase between primary and secondary. This is patently wrong as it violates Kirchoffs laws, and obviously ignores Lenz's law!

The EMFs are in phase in relation to turns ratio (assuming 100% coupling) and the currents are 180 degrees apart.

More generally a transformer with several windings tries to keep the flux change minimized, so that the total of amp-turns from every winding is effectively zero (assuming an ideal transformer).

Or put another way the primary winding is a load and the secondary is a source of EMF, in one case VI is positive and the latter it is negative.