Practice technical discipline questions for Electrical Machines, Power Systems, Power Electronics & Drives, Control Systems, Network Theory, and Switchgear with worked solutions.
Marking scheme: +1.00 positive, 0.00 negative (CIL CBT Pattern).
A $3\text{-phase}$, $4\text{-pole}$, $50\text{ Hz}$ induction motor runs at a rotor speed of $N_r = 1440\text{ rpm}$ while developing a mechanical power output of $P_{\text{mech}} = 10\text{ kW}$. Assuming negligible mechanical and windage losses, what is the rotor copper loss ($P_{\text{cu}}$)?
A $400/5\text{ A}$ current transformer (CT) feeds an overcurrent induction disc relay set at a plug setting of $125\%$. If a primary fault current of $I_f = 3000\text{ A}$ occurs on the protected feeder, what is the Plug Setting Multiplier (PSM)?