Why is MAGX results 33mA lower using the AT3600 compared with measuring magnetizing current with a Yokogawa WT210?
When using an external source as a power supply (manual source/line supply option in the Editor external source setup, not as a power amplifier ) the power supply regulation has to be taken into account. When the power supply is connected to the AC Interface input, the applied voltage to the transformer may drop due to the effects of the source impedance. This will results in a lower than expected test voltage at the transformer and may result in lower than expected magnetizing current.
To compensate for this an offset can be applied in the MAGX test program to compensate for the lower applied voltage. Alternatively, the test voltage may be measured under load and the power supply adjusted to the desired test voltage.
When using an external power amplifier, the applied voltage is automatically adjusted by the AT3600-AC Interface to compensate for an power amplifier to transformer losses. This method using amplifier/analog control in the Editor is always preferred.