Experiment_21_The_Split-Phase_inductor_Motor - Part III

Experiment_21_The_Split-Phase_inductor_Motor - Part III -...

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21 1 Experiment 21 The Split-Phase inductor Motor - Part III OBJECTIVE To measure the starting and operating characteristics of the split-phase motor under load and no-load conditions. To study the power factor and efficiency of the split-phase motor. DISCUSSION The starting current of a split-phase motor is usually four to five times normal full-load current. This produces two effects: 1) the motor heats very rapidly during start-up: and 2) the high starting current can cause a large line voltage drop so that the starting torque may be seriously reduced. The no-load current is usually 60% to 80% of the full-load current, which is high compared to three-phase motors. Most of the no-load current is used to produce the magnetic field in the motor, and only a small portion is used to overcome mechanical friction and the copper and iron losses. Because of the large magnetizing current, the power factor of these motors is rarely more than 60%, even at full-load. Split-phase motors tend to be much noisier than their three-phase counterparts, because of the inherent 120 cycle mechanical vibration. This vibration can be reduced by using resilient rubber mounting supports. EQUIPMENT REQUIRED Power supply, AC Voltmeter, AC Ammeter, Capacitor-Start Motor, and Tachometer
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21 2 PROCEDURE CAUTION! High voltages are present in this Experiment. Do not make or modify any connections with the power on! The power should be turned off after completing each individual measurement! The grading in this section is 1 point for each correct answer. Starting current
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Experiment_21_The_Split-Phase_inductor_Motor - Part III -...

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