2.12 Z, ZB - Impedance, Impedance with Bias
The impedance test measures the impedance of a transformer winding by
applying a specified voltage and frequency and by measuring the current
that flows, calculating the magnitude of the complex impedance.
The load resistor is assumed to be on the fixture, but not shown on the
It is switched in circuit using an OUT test that must be inserted in the
program before the Z test. (The relay patterns associated with inserting
and removing fixture resistors have deliberately not been included in the
Z test dialogue for two reasons: a) it would make the dialogue too
complicated, and b) it is not always necessary - e.g. in the case of a
fixture where the resistor is permanently fitted in circuit).
The test voltage is applied to the input winding, and the voltage and
current measured. From the measured results the impedance is calculated.