Lab Information
EXPERIMENT NO. 13
TORQUE CHARACTERISTICS OF A CAPACITOR-START MOTOR
PURPOSE:
To study the torque-load characteristics of a capacitor-start motor.
APPARATUS REQUIRED:
1. One Multi-function motor MFM-100.
2. One PB-100 Prony Brake
3. One SLA-100 Strobe-Tuchometer
4. One Hampden AC voltmeter
5. One Hampden AC ammeter
6. One Hampden AC wattmeter
7. One 0 to 140 volt AC supply.
PROCEDURE:
1. Couple the Multi-function motor to the prony brake and make the connections shown in
Figure 27. Make sure the switch on the motor panel is OFF. Adjust the prony brake belt so that it
is slack.
2. Place a jumper across the current coils of the meters to protect them from overload during
starting. Have the instructor check your meter connections.
3. Adjust the AC supply to 115 volts. Switch on the motor using the start switch and adjust the
AC supply if necessary to maintain 115 volts.
4. Perform a load test on the motor starting at "no load" (slack belt), then apply 8 oz to 32 oz in
Steps of 8 oz. Record the motor's current, voltage, watts and speed for each load step.
5. Calculate the output horsepower using the following formula:
HP = T (IN-OZ) N (rpm) * 9.93 x 10-7
REPORT:
1. Show data fro Step #4 and computations for Step #5.
2. Plot the motor's watts, speed, and output horsepower as ordiantes versus the output torque as
abscissa. Are these the results you expected?
FIGURE 27