Electrical Transformers and Rotating Machines
4th Edition
ISBN: 9781305494817
Author: Stephen L. Herman
Publisher: Cengage Learning
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Question
Chapter 16, Problem 12RQ
To determine
The two devices used to eliminate the induced voltage produced in the rotor when the field excitation current is stopped.
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The supply frequency is 50 Hz. What will be
the rotor voltage frequency if the motor
speed is equal to 90% of synchronous
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05 Hz.
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Name three factors that determine the amount of voltage induced in the rotor of a wound-rotor motor.
Chapter 16 Solutions
Electrical Transformers and Rotating Machines
Ch. 16 - What conditions must be met before two alternators...Ch. 16 - How can the phase rotation of one alternator be...Ch. 16 - What is the function of the synchronizing lamps?Ch. 16 - What is a synchroscope?Ch. 16 - Assume that alternator A is supplying power to a...Ch. 16 - What two factors determine the output frequency of...Ch. 16 - At what speed must a six-pole alternator turn to...Ch. 16 - What three factors determine the output voltage of...Ch. 16 - What are slip rings used for on a rotating field...Ch. 16 - Is the rotor excitation current AC or DC?
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- The reason why the starting torque of a series motor is higher than a shunt motor is because the series motor has O more current flowing through its armature O a stronger net magnetic field around both coils during the inrush of stator currentarrow_forwardWhen a repulsion-start induction-run motor reaches about 75% of rated full-load speed, it stops operating as a repulsion motor and starts operating as a squirrel-cage motor. What must be done to cause the motor to begin operating as a squirrel-cage motor?arrow_forwardQuestion 2 Beli vifth Slack side Motor (imprut) Tight side Beli thickpess\ Centre distance Figure 2 Figure 2 shows an open flat belt drive connected to a motor and a pulley. The motor transmits 20 kw to the connect pulley of 450 mm diameter and is rotating at 850 r/min to a second pulley rotating at 400 r/min. The distance between pulley centres is approximately 2 m. The belt is 6 mm thick and has a density of 970 kg/m. The maximum stress in the belt is not to exceed 2,7 MPa. The coefficient of friction for both pulleys is 0,3. Determine: 2.1. The diameter of the second pulley. 2.2. The length of the belt. 3.3. The width of the belt taking centrifugal tension into account.arrow_forward
- What type of field winding is made with many turns of small wire?arrow_forwardWhat is the standard current rating for the secondary winding of a CT?arrow_forwardQ3) A 220 V d.c series motor has armature and field resistances of 0.15 Q and 0.10 Q respectively. It takes a current of 30 A from the supply while running at 1000 rpm. If an external resistance of 1 Q is inserted in series with the motor, calculate the new steady state armature current and the speed. Assume the load torque remains constant.arrow_forward
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