Lab Information
EXPERIMENT NO. 17
SPEED-TORQUE CHARACTERISTICS OF A WOUND-ROTOR MOTOR
PURPOSE:
To Study the effects of added rotor resistance on the speed and 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 208-30 Power supply
7. One SLA-100 Strobe-Tachometer
PROCEDURE:
1. Couple the motor to the Prony Brake. Make the connections shown in Figure 32. Make sure
the Prony belt is slack.
2. Have the instructor check your machine and meter connections. A jumper cable should be
placed across the current coils of the meters to protect them from overload during starting. Make
sure the start switch on the motor's panel is OFF.
3. Place the wound-rotor controller in its maximum position, fully CCW. Set the input voltage to
208V.
4. Start the motor and perform a load testing at "no load" and then apply 8 oz. to 32 oz. in steps
of 8 oz. Record the voltage, stator current, rotor currents, and speed for each load step.
5. Calculate the output horsepower for each load step.
REPORT:
1. Plot the speed and output horsepower as ordinates versus the torque as abscissa for each load.
2. Show the data for Step #4 and the calculations for Step #5.
3. Explain the variance or invariance in the rotor currents for the load. test.