A shunt-connected 75kW, 250V DC motor has an armature resistance of 45mohm and a fieldresistance of 185ohm. When operated at 250V its no-load speed is 1850rpm. The motor isoperating under load at a terminal voltage of 250V and a terminal current of 290A.a. Calculate the motor speed, load power, load torque in this operation point.b. Assuming the load torque remains constant as a function of speed, calculate the motorspeed if the terminal voltage is reduced to 200V.Solution: na 1754 rpm; Pload = 69 kW; Tload = 372 Nm; nb = 1700 rpm; lb = 362 A=

Given a shunt connected 75 kW,250 V DC motor Armature resistance Ra= 45 mΩ Field resistance Rf=185…

Answered: A shunt-connected 75kW, 250V DC motor…

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

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A250 V, dc shunt motor has an armature resistance of 0.5 chmand a field resistance of 250 chm When driving a load df constant tarque at 600 r.p.m, the armeture current is 20 A If it is desired to raise the speed fram600 to 800 r.p.m, what resistance should be inserted in the shunt field circuit? Assume that the magnetic circut is unsaturated
-A 250V, DC series motor has total resistance of 0.8 Q. Its full load current and speed are 10 A and 1500 r.p.m respectively. If the torque is reduced to 50% .Determine the current and speed. Assume straight line magnetization characteristics.
(b) A 2 pole 220 V, 100A, and 850 rpm separately excited DC motor has an armature resistance of 0.15 0. Two field coils are connected in parallel and used to drive a load with the torque of TL = 400 – 0.2N, Nm Where N is the motor speed in rpm. Armature voltage control and two field windings connected in series are used in speed control below and above the rated, respectively. (i) Calculate the motor armature current and speed when the armature voltage is reduced to 110VV. (ii) Examine the motor speed and current when field coils are connected in series.
On full load a 500-volt series motor takes 100-Amp and runs at 840 rpm. The armature resistance of 0.1-ohm, field resistance 0.04-ohm. Find the speed when developing haft full load toque but with a 0.08-ohm diverter resistance parallel with the series field winding. Assume flux proportion to the field current.
A 220 V dc shunt motor develops a total torque of 100 N-M and takes 29A at 600 rpm. The armature and shunt field resistance are 0.3 ohm and 220 ohms respectively. If the speed is to be increased to 800 rpm determine the percentage reduction of the field and additional resistance to be inserted in the field circuit. The torque develop at 800 rpm is 70 N-M.
A 240V , Shunt DC - motor delivers power to a load at 1200 Rev / Min . The load Torque drawn by the motor is 320 N.m. The armature %3 resistance is 0.3 Ohm and the field resistance is 100 Ohm and the rotational losses are 500W. a. What are the armature current and the efficiency ? b. If the torque decreased to be 250 N.m find the speed !
A 240 V, DC shunt motor draws 15 A while supplying the rated load at a speed of 100 rad/s. The armature resistance is 0.5 Q and the field winding resistance is 80 Q. The net voltage across the armature resistance at the time of plugging will be
A 10 kW, 250 V Shunt motor has an armature resistance of 0.5 ohm and a field resistance of 200 ohm. At no load and rated voltage, the speed is 1200 rpm and the armature current is 3 A. At full load and rated voltage, the line current Is 47 A and because of armature reaction, the flux is 4 % less than it no load value. a.) What is the full load speed? b.) What is the developed torque at fll load?1158 rpm
A 10 kW, 250 V Shunt motor has an armature resistance of 0.5 ohm and a field resistance of 200 ohm. At no load and rated voltage, the speed is 1200 rpm and the armature current is 3 A. At full load and rated voltage, the line current is 47 A and because of armature reaction, the flux is 4 % less than it no load value. a.) What is the full load speed? b.) What is the developed torque at full load?
QUESTION 2 a) Draw the equivalent circuit and torque-speed characteristic curve for a series DC motor. b) Briefly explain the induced torque occurs in a series DC motor. e) A 20-hp 240-V 76-A 900 rimin series motor has a field winding of 33 turns per pole. Its armature resistance is 0.09 2, and its field resistance is 0.06 2. The magnetization curve expressed in terms of magnetomotive force versus Ex at 900 rimin is given by the following table: Table Q2 c): The magnetomotive force table for a de motor taken at 900r'min E. V 95 150 188 212 229 243 F.A tuus 1000 1500 2000 2500 500 3000 If the motor running at 33 percent of the full-koad armature current, determine: ) The motor's power converted from electrical to mechanical form, Prene i) The motor's torque, Tnit ii) The motor's speed, n
A 3 phase, 1500 rpm, 2200 V, star connected synchronous motor has an impedance of 0.4+j90 per phase. At some excitation 2900 V is induced in the armature. Find the maximum torque developed by motor before the motor breaks out of synchronism. Also find the load angle this time.
A 230V dc shunt motor has armature and field resistances of 0.3 W and 140 W respectively. Calculate the induced emf and the torque developed by the motor when it runs at a speed of 800 rev min-1 and the armature current is 2A. To drive a larger load at 1000 rev min-1 an additional resistance, R is connected in series with the field winding. In this situation the armature current is 30A. Calculate the new induced emf and torque and the value of R. Assume that the flux is directly proportional to the field current

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