Vt= Mains voltage Vt= 1027 Volts When a shunt motor with an armature resistance of 6 Ohm and a shunt winding resistance of 150 Ohm is operated from a constant source of 1027 Volts, it first rotates at 850 rpm and draws 6 amps of armature current. (There is no heating, the excitation current is constant in all cases, the machine is magnetically linear and there is no armature reaction effect.) a) If the shaft of the motor is blocked, how many amps will the total current drawn from the source be? b) What is the value of the external starting resistor Rx, which must be added to the armature circuit in order to limit the armature current to 50 amps at the time of starting, in Ohms? c) After starting, the motor accelerates and the starting resistance is reset. Then the motor is loaded and the new armature current becomes 30 amps. In this case, what would be the new number of revolutions in the steady state? d) Mechanical losses are 150 Watts. Find the shaft moment in the operation in part c.
Vt= Mains voltage
Vt= 1027 Volts
When a shunt motor with an armature resistance of 6 Ohm and a shunt winding resistance of 150 Ohm is operated from a constant source of 1027 Volts, it first rotates at 850 rpm and draws 6 amps of armature current.
(There is no heating, the excitation current is constant in all cases, the machine is magnetically linear and there is no armature reaction effect.)
a) If the shaft of the motor is blocked, how many amps will the total current drawn from the source be?
b) What is the value of the external starting resistor Rx, which must be added to the armature circuit in order to limit the armature current to 50 amps at the time of starting, in Ohms?
c) After starting, the motor accelerates and the starting resistance is reset. Then the motor is loaded and the new armature current becomes 30 amps. In this case, what would be the new number of revolutions in the steady state?
d)
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