Lab Information
EXPERIMENT NO. 16
STARTING CHARACTERISTICS OF A WOUND-ROTOR MOTOR
PURPOSE:
To study the effect of added rotor resistance on the starting torque of a wound-rotor motor.
APPARATUS REQUIRED:
1. One WRM-100 Wound-Rotor Motor
2. One PB-100 Prony Brake
3. One WRSC-100 Wound-Rotor Controller (or WRSC-300)
4. Two Hampden AC Ammeters
5. One Hampden AC Voltmeter
6. One 0 to 208V-30 power supply
PROCEDURE:
1. Couple the motor to the Prony Brake. Make the connections of Figure 31. Make sure the
Prony Brake belt is tight against the pulley so the motor cannot rotate. Turn the wound-rotor
fully counter-clockwise to its maximum resistance position.
2. Have the instructor check your connections and brake hookup. Make sure the motor start
switch on the motor panels is OFF.
3. Switch on the 0 to 208V-30 Power Supply and adjust its output from zero up to 104 volts 30.
Switch on the motor and quickly record the torque and stator current.
4. Repeat Step #3 with the wound-rotor controller in its mid-resistance position.
5. Repeat Step #3 with the wound-rotor controller in its minimum resistance position.
6. Assuming that the starting current is directly proportional to the voltage applied, predict the
starting current at full line voltage for each start test.
FIGURE 32