Understanding Motor Controls
4th Edition
ISBN: 9781337798686
Author: Stephen L. Herman
Publisher: Delmar Cengage Learning
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Chapter 4, Problem 12RQ
To determine
The size of the overload heater that should be used to protect the motor.
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What is the Relay Number and its law?
Problem 5
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Where and why is a centrifugal switch used in a split-phase motor?
2.
Why and where is a capacitor used in the single-phase AC motor?
3. What type of motor would you select to perform each of the following jobs?
(a) Electric drill:
(b) Refrigerator:
(c) Hair driers and desk fans:
(d) Air Conditioner Fan:
(e) XY plotters and printers:
(f) Electric clock:
The working current has a power of 100 kW and a power factor of 0.50. After a capacitor of 75 KVAR is installed, what does the
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B 0.71
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Chapter 4 Solutions
Understanding Motor Controls
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.Similar questions
- A three-phase motor nameplate indicates a full load current of 362 amperes. The nameplate indicates that the heaters are to be sized for 125% of motor full load current. Current transformers with a ratio of 600:5 are used to reduce the motor current. Using the chart shown in Figure 4–7B, determine the size of overload heaters needed to protect this motor.arrow_forwardA large motor has a full load current rating of 425 amperes. Current transformers with a ratio of 600:5 are used to reduce the current to the overload heaters. What should be the full load current rating of the overload heaters?arrow_forwardThe motor nameplate of a wye-delta started motor has a full load current of 287 amperes. What current rating should be used to determine the proper overload heater size?arrow_forward
- Name three factors that determine the amount of induced voltage.arrow_forwardA 480-volt three-phase load is rated at 34.5 kVA. It is to be supplied with variable three-phase voltage. Because the load is continuous, the transformers ratings are to be increased by 1.25% of the rated load. Three variable autotransformers are used to supply this load. Refer to Table 4-2 and determine the standard size of each transformer that should be used to make this connection.arrow_forwardPower-consuming devices are wired in _____(series orparallel).arrow_forward
- Refer to Figure 211 to answer the following questions. How much voltage will be applied to coil 1CR when it is energized?arrow_forwardRefer to the transformer shown in Figure 5-13 to answer the following questions. The transformer shown in Figure 5-13 is supplying 325 volt amperes to a load. The primary voltage is 240 volts. What is the primary current? Figure 5-13 Autotransformer practice problems.arrow_forwardWhat environmental conditions affect the life of a transformer?arrow_forward
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