91Ó°ÊÓ

A 6-pole, single-phase motor is connected to a \(60 \mathrm{~Hz}\) source. What is its synchronous speed?

What is the purpose of the auxiliary winding in a single-phase induction motor? How can we change the rotation of such a motor?

State the main difference between a splitphase motor and a capacitor-start motor. What are their relative advantages?

Explain briefly how a shaded-pole motor operates.

List some of the properties and advantages of a universal motor.

Why are some single-phase motors equipped with a resilient mounting? Is such a mounting necessary on 3-phase motors?

What is the main advantage of a capacitorrun motor?

The palm of the human hand can just barely tolerate a temperature of \(130^{\circ} \mathrm{F}\). If the full-load temperature of the frame of a \(1 / 4 \mathrm{hp}\) motor is \(64^{\circ} \mathrm{C}\) in an ambient temperature of \(76^{\circ} \mathrm{F}\), a. Can a person keep his hand on the frame? b. Is the motor running too hot?

a. A single-phase motor vibrates at a frequency of \(100 \mathrm{~Hz}\). What is the frequency of the power line? b. A capacitor-run motor does not have to be set in a resilient mounting. Why? c. A 4-pole, \(60 \mathrm{~Hz}\), single-phase hysteresis motor develops a torque of 6 in.lb when running at \(1600 \mathrm{r} / \mathrm{min}\). Calculate the hysteresis loss per revolution [J].

The line is composed of a 2 -conductor cable made of No. 12 gauge copper. The ambient temperature is \(25^{\circ} \mathrm{C}\) and the service entrance voltage is \(122 \mathrm{~V}\). Calculate the following: a. The resistance of the transmission line b. The starting current and the voltage at the motor terminals