Question

The power to a single-phase 3.3kV load with a peak demand of 200kVA is measured via a single wattmeter with a 110V max rated voltage coil and a max rated current coil of 5A. Establish: a) a suitably ratio for the instrument class voltage and current transformer to enable the wattmeter to provide a full scale reading up to the peak loading assuming unity power factor b) Assuming the supply voltage is constant what would be the voltage across the wattmeter voltage coil and the current through the wattmeter current coil when the wattmeter was reading 100kW at a load p.f of 0.8 . c) Draw a schematic showing the connections to the wattmeter coils via the instrument transformers -include the terminal and polarity markings.

Answer 1