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A single phase motor is connected to 400V, 50Hz supply. The motor draws a current of 31.7A at a power factor 0.7 lag. The additional reactive power (in VAR) to be supplied by the capacitor bank will be ___________

Correct Answer: 4756
Active power drawn by the motor=VIcosФ = 400*31.7*0.7 = 8876 W Reactive power = VIsinФ=400*31.7*sin(45.57.29) = 9055.3 VAR New power factor=cosθ2 = 0.9 θ2=cos-1(0.9) Q2=8876*tan(25.84) = 4298.855 VAR Change in reactive power=9055.3-4298.855 = 4756.4 VAR.

A single phase motor is connected to 400V, 50Hz supply. The motor draws a current of 31.7A at a power factor 0.7 lag. The capacitance required in parallel with motor to raise the power factor of 0.9 lag (in micro farads) is ___________

A single phase motor is connected to 400V, 50Hz supply. The motor draws a current of 31.7A at a power factor 0.7 lag. The capacitance required in parallel with motor to raise the power factor of 0.9 lag (in micro farads) is __________

Given that 100.48=x, 100.70=yandxz=y2, then the value ofzis close to ___ ?

Discrete transistors T1 and T2 having maximum collector current rating of 0.75A are connected in parallel as shown in the figure. This combination is treated as a single transistor to carry a single current of 1A, when biased with a self bias circuit. When the circuit is switched ON, T1 had draws 0.55A and T2 draws 0.45A. If the supply is kept ON continuously, it is very likely that_________

A three-phase balanced delta connected load of (4+j8) Ω is connected across a 400V, 3 – Ø balanced supply. Determine the phase current IR. Assume the phase sequence to be RYB.

A single wattmeter is connected to measure the reactive power of a three-phase, three-wire balanced load. The line current is 17A and the line voltage is 440V. Calculate the power factor of the load if the reading of the wattmeter is 4488 VAR.

If a 400 V, 50 hz star connected, 3-phase squirrel cage induction motor is operated from 400V and 75 Hz supply. The torque that the motor can now provide while drawing rated current from the supply will _________

At a 33kV 50 Hz to a bus a load of 35 MW is connected. To improve the power factor to unity a synchronous phase modifier is connected taking 5 MW. If the SPM is represented as delta connected impedance, where in each phase we have capacitor connected parallel to resistance forming RC parallel network, then the value of this resistance is ___________

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