Concept explainers
Identify why it is desirable to disconnect the autotransformer from the circuit hen the motor reaches the run stage.
Explanation of Solution
The autotransformer is used to reduce the amount of inrush current by reducing the voltage applied to the motor at the time of starting. When the motor reaches 75% of the normal speed it is said to have reached run state.
After reaching the run state, full voltage can be supplied to the motor. The use of autotransformer to provide full voltage to the motor is a waste of energy as the same can be applied directly.
Hence, it is desirable to disconnect the autotransformer after the motor reached the run state to save energy and extend the life if the autotransformer.
Want to see more full solutions like this?
Chapter 25 Solutions
Bundle: Understanding Motor Controls, 4th + Mindtap Electrical, 2 Terms (12 Months) Printed Access Card
- Refer 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 difference between a motor starter and a contactor?arrow_forwardWhat is the function of a micro limit switch when used with a manual controller for a wound rotor motor?arrow_forward
- When a diac first turns on, does the voltage drop, remain at the same level, or increase to a higher level?arrow_forwardA manual motor starter controls a single phase 120 volt motor. The motor is not running, and theswitch handle on the starter is found to be in thecenter position. What does this indicate?arrow_forwardWhat is the advantage of a capacitor start induction run motor over a resistance start induction run motor?arrow_forward
- Understanding Motor ControlsMechanical EngineeringISBN:9781337798686Author:Stephen L. HermanPublisher:Delmar Cengage LearningElectrical Transformers and Rotating MachinesMechanical EngineeringISBN:9781305494817Author:Stephen L. HermanPublisher:Cengage LearningRefrigeration and Air Conditioning Technology (Mi...Mechanical EngineeringISBN:9781305578296Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill JohnsonPublisher:Cengage Learning