WHAT IS THE “IMPEDANCE” OF A TRANSFORMER?
It is really no more than a label which can be attached to a transformer or a winding. If you measure the impedance of the primary winding you will see the “reflected” impedance of the load you connect to the secondary winding. “Reflected” means multiplied by the turns ratio squared. For example if you connect a 10,000 ohm resistor to the secondary of a 1:10 step up transformer and measure the input impedance you will measure approximately 10,000 X (0.1 squared) ohms i.e.100 ohms. (This is only approximate because you will need to allow for the primary inductance and the dc resistance of the windings). The impedance “label” just gives an idea of the impedance of the circuit in which it could be used.
