A 50 Hz balanced three-phase, Y-connected supply is connected to a bal anced three-phase Y-connected load. If the instantaneous phase -a of the supply voltage is Vcos ( t) and the phase-a of the load current is Icos ( t ), the instantaueous three-phase power is

time-varying with an aver age value of (3/2)VI cos and a frequency of 100 Hz.

a constant with a magnitude of VI cos

a constant with a magnitude of (3/2)VI cos

time-varying with an aver age value of (3/2)VI cos and a frequency of 100 Hz.

time-varying with an average value of VIcos and a frequency of 50 Hz.

A 50 Hz balanced three-phase, Y-connected supply is connected to a bal

1.	A 50 Hz balanced three-phase, Y-connected supply is connected to a bal anced three-phase Y-connected load. If the instantaneous phase -a of the supply voltage is Vcos ( t) and the phase-a of the load current is Icos ( t ), the instantaueous three-phase power is
A.	a constant with a magnitude of VI cos
B.	a constant with a magnitude of (3/2)VI cos
C.	time-varying with an aver age value of (3/2)VI cos and a frequency of 100 Hz.
D.	time-varying with an average value of VIcos and a frequency of 50 Hz.
Answer» C. time-varying with an aver age value of (3/2)VI cos and a frequency of 100 Hz.

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