(a) Show that the total power in a 3-phase, 3-wire system using the two-wattmeter process of measurement is given by the sum of the wattmeter readings. Illustrate a connection diagram.
(b) Illustrate a phasor diagram for the two-wattmeter method for a balanced load.
(c) Use the phasor diagram of part (b) to derive a formula from which the power factor of a 3-phase system may be determined using only the wattmeter readings.