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 = sX2. R2 = s2X2. sR2 = X2. R2 = s2X2. R2 = sX2. R2 = s2X2. sR2 = X2. R2 = s2X2. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following bearings and their uses are correct ball bearings → small machines neither 1 nor 2 both A and B roller bearings → large machines ball bearings → small machines neither 1 nor 2 both A and B roller bearings → large machines ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If starting current of a 3 - Φ induction motor is 5 times the rated current, while rated slip is 4 %, then ratio of starting torque to full load torque is 1. 0.4. 0.6. 0.8. 1. 0.4. 0.6. 0.8. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to 0.125 p.u 0.5 p.u 0.75 p.u 0.25 p.u 0.125 p.u 0.5 p.u 0.75 p.u 0.25 p.u ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A separately excited DC motor has an armature resistance of 0.5 Ohm. The supply voltage is 250V. Armature current is 20A and the speed of rotation is 1500 rpm. Find the torque developed? 15.6 Nm 16.55 Nm Zero 15.28 Nm 15.6 Nm 16.55 Nm Zero 15.28 Nm ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Two of supply terminals to a 3 - Φ induction motor get interchanged during re-connection after normal maintenance. When switched on the supply, the motor will not start at all. rotate in the same direction as before maintenance. get heated and damaged. rotate in direction opposite to that before maintenance. not start at all. rotate in the same direction as before maintenance. get heated and damaged. rotate in direction opposite to that before maintenance. ANSWER DOWNLOAD EXAMIANS APP
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