Understanding Motor Controls
4th Edition
ISBN: 9781337798686
Author: Stephen L. Herman
Publisher: Delmar Cengage Learning
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Chapter 42, Problem 4RQ
A motor is tripping out on overload. The motor nameplate reveals a full load current of 168 amperes. When the motor is operating under load, an ammeter indicates the following: Phase #1 = 166 amperes, Phase #2 = 164 amperes, and Phase #3 = 225 amperes. What is the most likely problem with this motor?
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Chapter 42 Solutions
Understanding Motor Controls
Ch. 42 - What are the three main electrical test...Ch. 42 - What is the advantage of a plunger type voltage...Ch. 42 - A motor is tripping out on overload. The motor...Ch. 42 - A motor is tripping out on overload. The motor...Ch. 42 - Prob. 5RQCh. 42 - Refer to the circuit shown in Figure 42–17. Assume...Ch. 42 - Prob. 7RQCh. 42 - Refer to the circuit shown in Figure 4221. Assume...Ch. 42 - Prob. 9RQCh. 42 - Refer to the circuit shown in Figure 42–21. Assume...
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- A motor is tripping out on overload. The motor nameplate reveals a full load current of 68 amperes. When the motor is operating under load, an ammeter indicates the following: Phase #1 = 106 amperes, Phase #2 = 104 amperes, and Phase #3 = 105 amperes. What is the most likely problem with this motor?arrow_forwardAssume that a nine-lead dual-voltage motor is being tested with an ohmmeter. The meter indicates resistance values as follows: T7–T8 = 6Ω, T7–T9 = 6Ω, and T8–T9 = 10Ω. What would these readings indicate?arrow_forwardA motor nameplate lists the voltage as 208–230/460. The nameplate also lists the full-load amps as 34.2–31.6/15.8. If the motor is operated at 240 volts, what should be the full-load current?arrow_forward
- A wye-connected load has a voltage of 480 V applied to it. What is the voltage dropped across each phase?arrow_forwardRefer to the schematic diagram in Figure 318. Assume that the motor is not running. When the third speed push button is pressed, the motor starts in its lowest speed. After a delay of 3 seconds, the motor accelerates to second speed and 3 seconds later to third speed. After a period of about 1 minute, the fourth speed push button is pressed, but the motor does not accelerate to fourth speed. Which of the following could cause this problem? a. Control relay CR2 coil is open. b. S2 contactor coil is open. c. CR3 coil is shorted. d. S3 contactor coil is open.arrow_forwardWhat is the minimum pulley diameter for a 1 HP motor running at 1750 RPM?arrow_forward
- For a cylindrical-rotor synchronous machine, the magnitude of the internal generated voltage is |Eg| = 240 volts, and the magnitude of the terminal voltage is |Vt| = 200 volts. Which of the following is true? a. The machine is operating as a generator. O b. The machine is operating as a motor. O C. Information is insufficient to determine the operating mode of this machine.arrow_forwardHow many lines of magnetic flux must be cut in 1 s to induce a voltage of 1 V?arrow_forwardWhat unit controls the voltage applied to the armature?arrow_forward
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