The two wattmeter method is used to measure active power on a three phase, three wire system. If the phase voltage is unbalanced, then the power reading is

A $$3$$ - $$\phi $$ load operates with balanced voltages applied to its terminals, and draws balanced currents. The potential coil of a moving coil wattmeter is connected from $$R$$ to $$Y$$ terminals of the load. The current coil of the meter is connected in series with phase $$B.$$ by appropriate derivation, show that the quantity indicated by this wattmeter is proportional to the reactive power drawn by the load

Instrument transformers are known to introduce magnitude and phase errors in measurements. These are primarily due to

A $$2300$$ $$V,$$ $$3$$-phase synchronous motor driving a pump is provided with a line ammeter and a field rheostat. When the rheostat is adjusted such that the $$ac$$ line current is minimum. The ammeter reads $$8.8$$ $$A.$$ What is the power being delivered to the pump, neglecting losses? How should the rheostat be adjusted so that the motor operates at $$0.8$$ leading power factor? How many $$kVARs$$ is the motor supplying to the system at this new power factor?