Electric Motor Control
10th Edition
ISBN: 9781133702818
Author: Herman
Publisher: CENGAGE L
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Chapter 39, Problem 13SQ
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Choose the correct option to find the location where the DC excitation is applied.
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Chapter 39 Solutions
Electric Motor Control
Ch. 39 - Prob. 1SQCh. 39 - What is the effect of the starting winding of the...Ch. 39 - What are typical applications of synchronous...Ch. 39 - Prob. 4SQCh. 39 - A loaded synchronous motor cannot operate...Ch. 39 - Why must a discharge resistor be connected in the...Ch. 39 - Depending on their power factor ratings, what is...Ch. 39 - At what power factor do incandescent lights...Ch. 39 - Prob. 9SQCh. 39 - The speed of a synchronous motor is fixed by the...
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- L-1). The 3-phase wound-rotor induction motor has .... . a) high starting torque b) low starting current c) both "a" and "b" d) neither "a" nor "b" L-2). The 3-phase wound-rotor induction.........a) motor has a wire wound rotor b) motor's rotor can be connected to an external resistive load by way of slip rings and brushes c) motor requires more maintenance than the 3-phase squirrel-cage induction motor d) all of the above L-3). The 3-phase wound-rotor induction motor's rotor circuit's resistance should be adjusted so it is__________ during starting. a) low b) high c) either "a" or "b" d) neither "a" nor "b" L-4). Will a 3-phase wound-rotor induction motor start with no external circuit connected to its rotor leads? a) yes b) noarrow_forwardCompensating winding is placed in the pole shoe O all of the above O armature core O main field Oarrow_forwardurgent please no need to explanationarrow_forward
- Speed control of a 140 V, 1.68 kW DC motor single phase thyristor full wave AC-DC It is made by the converter. AA supply voltage 220 V (rms) Is 50. In the converter It is assumed that there is no loss. The armature resistance of the DC motor is = 0.417 Q. Very a large inductance is connected in series with the motor. The motor voltage constant is = 0.0964 V/rpm. The motor can be considered as a permanent magnet DC. According to this, a) Draw the driver (converter-motor) power circuit. b) Calculate the nominal current of the motor. c) Supply voltage, supply current, converter output voltage for ignition angle a = 30 ° and Draw the waveforms for the converter output current. d) = 950 rpm and for nominal current, d1) The firing angle of the converter, d2) Effective value of supply and thyristor current, d3) Supply power factor, calculate.arrow_forwardThe resistance of the field winding(copper wire) of a DC machine is 0.25 ohm at 25°C. When operating at full-load, the temperature of the winding is 75 °C. The temperature coefficient of resistance of copper is 0.00427 per °C at 0°C. Find the resistance of the field winding at full-load.arrow_forward6- In a stepper motor, how is the speed of rotation determined? a) By the current supplied to the motor. b) By the magnitude of the voltage applied. c) By the load applied to the motor. d) By the frequency of the waveforms used. 7- A transformer core is laminated to a) reduce hysteresis loss b) reduce eddy current losses c) reduce copper losses d) reduce all above losses 8- An induction motor with 580 r.p.m. speed at 60 Hz will have a) 8 poles b) 6 poles c) 4 poles d) 2 poles 9- If any two phases for an induction motor are interchanged a) the motor will run in reverse direction b) the motor will run at reduced speed c) the motor will not run d) the motor will burn 10- No-Load speed of which of the following motor will be highest? a) Shunt motor b) Series motor c) Short-Shunt compound motor d) Long-Shunt compound motorarrow_forward
- 1.5 A 10‐pole, 380 ‐V, 50 Hz, D‐connected three‐phase induction motor is rotating a quarry belt conveyor. The machine has the following parameters, referred to the stator, on a per phase basis: Stator Parameters Winding Resistance................0.19 Ω ......... Winding Reactance.................1.12 Ω.......... Rotor Parameters Winding Resistance......................0.29 Ω Winding Reactance.....................1.12 Ω Magnetising Reactance................................16.8 Ω Equivalent Core‐loss Resistance....................900 Ω. The friction and windage losses are 320 W. When the motor runs at its rated slip of 2.6 %. Determine: 1.5.1 The stator current. 1.5.2 Estimate the Output torque of the motor under the rated conditions. 1.5.3 The Motor…arrow_forwarda. Explain the terms, coil span, coil pitch, short pitching and chording of coils.b. Equalizer rings are needed in lap wound dc machines not in wave wound explain the reason andthe use of equalizer rings with the help of an example.c. What are dummy coils?d. What is the purpose of using short-pitched coils in ac windings?arrow_forwardi need the answer quicklyarrow_forward
- A freewheeling DC motor is driven with 1000 rpm and a nominal load torque of 80Nm. The field circuit resistance is 200 and the armature circuit resistance is 0.2 O. The field coils are fed with a zero degree transmission angle through a single-phase fully controlled converter connected to a single-phase 240V source. The armature circuit is fed from a single phase 400V source through another fully controlled converter. Magnetic saturation has been neglected, the motor constant is given as 0.8 V - s / A - rad. Assuming that there is no fluctuation in armature and field current, find the control angle of the converter feeding the armature at nominal load. If you want to leave the question blank, click again on the option you marked.arrow_forwardState the types of induction motorarrow_forwardA direct current shunt dynamo continuously supplies an ohmic load of 50 Ohm at terminal voltage Vt= 1000 V. The armature winding resistance is 5 Ohm and the shunt pole winding resistance is 200 Ohm. The sum of mechanical losses is 400 W. What is the percent efficiency of the dynamo under these operating conditions? a) 70 b) 74 c) 87 d) 78 e) 85arrow_forward
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