Electrical Machines A self-excited shunt generator fails to build up, because 1. the field circuit is open 2. The armature circuit is open 3. the residual magnetism is absent 4. The direction of rotation is wrong From these, the correct answer is 1, 2 and 3 1, 3 3 only 1, 2, 3 and 4 1, 2 and 3 1, 3 3 only 1, 2, 3 and 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines When the armature current of 5 Amp is flowing through the dc motor the torque produced is 47 Nm. Keeping the speed constant if the armature current is increased to 7 amp, calculate the new torque. Assume losses to be constant. 27.73 Nm . 65.8 Nm. 74 Nm. 38.5 Nm. 27.73 Nm . 65.8 Nm. 74 Nm. 38.5 Nm. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In synchronous generator V curve is drawn between either of these. field current on X-axis and armature current on Y-axis. field current on X-axis and power factor on Y-axis. field current on Y-axis and armature current on X-axis. either of these. field current on X-axis and armature current on Y-axis. field current on X-axis and power factor on Y-axis. field current on Y-axis and armature current on X-axis. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines When R2 is rotor resistance, X2 the rotor reactance at supply frequency and s the slip, then the condition for maximum torque under running condition will be R2 = s2X2. R2 = s2X2. R2 = sX2. sR2 = X2. R2 = s2X2. R2 = s2X2. R2 = sX2. sR2 = X2. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a synchronous generator with constant steam input supplies power to an infinite bus at a lagging power factor. If the excitation is increased power angle increase and power factor decrease both power angle and power factor increase power angle decrease and power factor increase both power angle and power factor decrease power angle increase and power factor decrease both power angle and power factor increase power angle decrease and power factor increase both power angle and power factor decrease ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Wave winding is employed in DC machine of high current and low voltage rating. low current and high voltage rating. high current and low voltage rating. low current and low voltage rating. high current and low voltage rating. low current and high voltage rating. high current and low voltage rating. low current and low voltage rating. ANSWER DOWNLOAD EXAMIANS APP
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