Question

A single phase voltage controller has input of 230 V and a load of 15 Ω resistive. For 6 cycles on and 4 cycles off, determine the power delivered to the load.

(a) 2.1 W

(b) 2.1 kW

(c) 516 W

(d) 5.16 kW

This question was posed to me by my college director while I was bunking the class.

This question is from AC Voltage Controllers-3 topic in portion Voltage Controllers of Power Electronics

Answer 1

Right option is (b) 2.1 kW

The explanation: Vrms = Vo x √k

k = (6/6+4) = 6/10 = 0.6

Vrms = √0.6 x 230 =   178.157 V

P = (Vrms)^2/R = 2116 W = 2.116 kW.