Electric Motor Control
10th Edition
ISBN: 9781133702818
Author: Herman
Publisher: CENGAGE L
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Chapter 31, Problem 4SQ
To determine
Explain why four motor contacts are there for high speeds and low speeds in Figure 31-4.
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Students have asked these similar questions
Synchronous motor when the load is taken completely while working at full load in all properties Does it change properties? Explain.
How to avoid the effect of the high current at starting of the Motor?
a.
variable resistor is connected in series with Armature circuit
b.
variable resistor is connected in parallel with Armature circuit
c.
variable resistor is connected in series with field circuit
d.
None of the above
Clear my choice
24.a. What type of drive is needed for a vertical lift bridge using two induction motors to operate the twoends of the bridge at the same time?A. Synchrotie driveB. Adjustable voltage driveC. Eddy-current couplingD. Adjustable frequency drive24.b. To prevent the motor speed from increasing until the motor fails mechanically, a load should always beconnected to aA. shunt d-c motor.B. series d-c motor.C. wound-rotor motorD. synchronous motor
Chapter 31 Solutions
Electric Motor Control
Ch. 31 - Excluding slip, at what speed (r/min) will an...Ch. 31 - What is meant by the description separate winding...Ch. 31 - Prob. 3SQCh. 31 - Prob. 4SQCh. 31 - In Figure 314, what does the broken line between...Ch. 31 - When the high button is depressed in Figure 314,...Ch. 31 - Which coils are energized immediately when the...Ch. 31 - At what speed can a four-pole, 240-volt, 5-hp,...Ch. 31 - What is meant by the compelling action produced by...Ch. 31 - Prob. 10SQ
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- In Figure 327, the motor cannot be started in high speed. Why?arrow_forwardWhy are different motor connections shown for what appears to be the same motor in the various diagrams in Figure 332? FIG. 332 Typical arrangements for four-speed, three-phase, two-winding motors.arrow_forwardA. The DC motor in Figure 3 on Worksheet 8 is aa) cumulatively connected short-shunt compound DC motor b) cumulatively connected long-shunt compound DC motor c) differentially connected short-shunt compound DC motor d) shunt DC motorB. Is the DC motor in Figure 1 on Worksheet 8 turning in the same direction as that in Figure 3?a) yes b) noarrow_forward
- (Im) Does the excitation circuit current change as the motor current changes? explain the reasons. (DC shunt motor).arrow_forwardIn Synchronous Motor Operation How the regulating characteristics can be obtained from V curve?arrow_forwardA 4 pole, 500V shunt motor has 720 wave connected conductors on its armature. The full load armature current is 60A and flux per pole is 0.03Wb. The armature resistance is 0.2Ω and contact drop per brush is 1V. What is the back emf? What is the developed torque?arrow_forward
- 3 phase , delta connection , 2 pole , 1000 Volt , 50 Hz asynchronous motor 2920 RPM (friction losses will not be considered) a) calculate the iron losses of the engine ? b)calculate the output power of the engine ? c)calculate the input power ? d) effiency ? thank you :)arrow_forwardWhen the high button is depressed in Figure 314, what prevents the high-speed starter from closing immediately?arrow_forwardA 240-volt shunt motor takes 5 amperes on no-load. The armature resistance is 0.25 ohm and the field resistance is 200 ohms. Calculate the efficiency when taking full load current of 50 amperes and the percentage change in speed between no-load and full-load.arrow_forward
- What is this motor's starting torque?arrow_forwardWhy would the slip not change? If you start the motor at 80% of the rated frequency, wouldn't that be 48 Hz?arrow_forward21.a. When field voltage is controlled to provide a method of variable speed control, the system is using aconcept known as fieldA. stability.B. drive.C. bias.D. weakening. 21.b. What type of motor has the same wire diameter in both the field and the armature coils?A. Interpole-woundB. Series-woundC. Compound-woundD. Shunt-woundarrow_forward
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