Electric Motor Control
10th Edition
ISBN: 9781133702818
Author: Herman
Publisher: CENGAGE L
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Chapter 54, Problem 4SQ
To determine
Explain whether the
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The following sequential statements, when completed, describe armature reaction in a DC generator. Complete each statement by inserting the appropriate word from among those provided in the word list below.
Notes: A word may be used more than once. There are more words than required.
Word list:armature, between, brushes, clockwise, commutator, currents, direction, distortion, increase, induces, inline, interpoles, main-field, neutral-plane, power, rotating, rotation, slip-rings, slow-down, sparking, speed, torque, voltage.
The effects of armature reaction can be reduced by equipping the DC machine with _________________ connected in series with the _______________, or by physically shifting the position of the __________________.
If this is not done _______________ will occur at the brushes and the generator output ________________ will be reduced.
Prolonged operation in this state can lead to sustained damage to the brushes and _________________.
Q. A 3-phase, star connected, 10 kVA, 400 V, salient pole alternator with direct and quadrature axis reactances of 15 ohm and 8 ohm respectively, delivers full-load current at 0.8 power factor lagging.Neglect the armature resistance. Solve this question to chose the correct answer for the following:
The direct axis and quadrature axis components of armature current are ........ and ......... respectively ?
The following information is given for a 300 kw, 600 V long shunt compound generator. Shunt field resistance = 75 Ω, armature resistance including brush resistance = 0.03 Ω, commutating field winding resistance = 0.011 Ω, series field resistance = 0.012 Ω, diverter resistance = 0.036 Ω. When the machine is delivering full load, calculate the voltage, power generated by the armature and efficiency.
Chapter 54 Solutions
Electric Motor Control
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- Q. A 3-phase, star connected, 10 kVA, 400 V, salient pole alternator with direct and quadrature axis reactances of 15 ohm and 8 ohm respectively, delivers full-load current at 0.8 power factor lagging.Neglect the armature resistance. Solve this question to chose the correct answer for the following: The load angle?arrow_forward4. A short shunt compound generator supplies a load of 10 kW at 200 V through a pair of feeder resistance of 0.10 ohm. Armature, shunt field resistance and series field resistance are 0.10 ohm, 52.5 ohms and 0.10 ohm, respectively. If the core, friction, and windage losses amount to 631 watts, determine (a) HP of driving engine (b) commercial, electrical and mechanical efficiencies.arrow_forwardA 440 V, 3-phase, delta connected cylindrical synchronous motor with synchronous reactance of Xsm=2Ω is connected to a turbo-generator with Xsg=3Ω through transmission line of reactance Xtr=1.5Ω. If its field current is adjusted to give an excitation voltage of 12 Kv, then Calculate: (a) Calculate the maximum magnitude of the resultant flux emf? (b) Calculate the magnitude of armature current and its P.F? (c) Calculate the magnitude of the armature current in phase with stator voltage? (d) Calculate the maximum power output from the motor? (e) Compute the excitation voltage Ef on a per unit basis, when the generator is delivering rated KVA at rated voltagee and at power factor of (i) 0.8 lagging and (ii)0.8 leading? (f) Draw the complete phasor diagram and show that armature current leading the terminal voltage?arrow_forward
- 2-) a) Explain the effect of the capacitor on the operation of the asynchronous machine as a generator. b) Squirrel-cage asynchronous motor, which has never been used before, as a generator in its first use will be run. Does the machine work as a generator? Explain.arrow_forwardThe armature resistance of a 3-phase, delta connected, rated speed of 1000 rpm and 6-pole synchronous generator is 0.4 ohm and the synchronous reactance is 2.4 ohm. While this generator is feeding a pure ohmic load of 37 kW, if the terminal voltage is 124 volts; in this situation. a) the no-load voltage of the generator, b) the moment applied to the generator shaft,calculate.arrow_forwardDC Electric Machine: synchronous machine: Which option is correct for the graph given regarding the synchronous machine? The order should be: name of the characteristic / run in (1) / run in (2) / run in (3) A) Idle running characteristic of the motor / capacitive / ohmic / Inductive. B) Setting characteristic of the generator / Pure inductive / ohmic / Pure capacitive. C) Setting characteristic of the generator / Inductive / ohmic / capacitive. D) External characteristic of the generator / capacitive / ohmic / Inductive. E) External characteristic of the motor / Inductive / ohmic / capacitivearrow_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 long-shunt compound d.c. generator with armature, series field and shunt field resistance of 0.5, 0.4 and 250 Ω respectively gave the following readings when run at constant speed : Load current (A) : 0 10 20 30 40Terminal p.d. (V) : 480 478 475 471 467 Plot the curve of internal generated e.m.f. against load current. Explain fully the steps by which this curve is obtained and tabulate the values from which it is plotted.arrow_forwardSquirrel-cage asynchronous motor, which has never been used before, as a generator in its first use will be run. Does the machine work as a generator? Explain.arrow_forward
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