When the electrical current rating of a energy meter under test is high a test with actual loading arrangements would involve a considerable waste of power. In order to avoid this "phantom loading" is done.
Phantom loading consists of supplying the pressure circuit from a circuit of required normal voltage, and the current from a separate low voltage supply. It is possible to circulate the rated current through the current circuit with a low voltage supply as the impedance of the circuit is very low. With this arrangement the total power supplied for the test is that due to the small pressure coil current at normal voltage, plus that due to the current circuit current supplied at low voltage. The total power, therefore, required for testing the meter with phantom loading is comparatively very small.
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