Scanned by Cartrickstarvivek.comNGFUFULAR PUBLICATIUNSRated filll IThe circuit diagram is draAt starting, the speed of the motor is zero, hence back emf developed is zero(E,P¢Z,where, n is the speed of the motor).The field current, I, = 120R, 60 A=2AIn the absence of E,, the armature current is very high, which is potentially detrimentsto the armature circuit. A starter is an additional resistance which limits the startimcurrent and ensures smooth operation of the motor, hence it is necessary.1,-1, +1,1=40 -2- 38 Aaack emf E, =V, -v.- Brush contact d34A shunt motor has a rated armature current oVThe rated speed of the motor is 1000 rpm. The armature resistance is 0.2 ohm, Findthe speed of the motor if total torque is reduced to 70% of that at rated load andohm resistance is inserted in series with the armature.me fluxconnected to 200ye of zeroal cmf or-(120-02x 38-3)V=(120-76-3)V =109 4Vfrom the[WBUT 2013]POZNE.60AAnswer:At rated loadPO E 109.4Virpm60A N 1800onductors.e armaturene full loadWBUT 2012]V= 200E, =V, -1r, =(200 - 0.2x10) V- (200 - 2) V =198 VTorque is proportional to current.Let 1, be the rated current at full load,Let 1, be the current when torque is 70% of that at rated load.or.At half load, line current =A= 20 A.The ficld current remains constant for constant terminal voltage ie, 2A,Hence, I = (20 - 2) A=18AThe new back emfE -V, - I'r, - Brush contact dropT 1,1, = 1,-10x0.7 = 7A=(120 - 0.2x18-3)V= (120-3.6-3)V=113AVor,E PO 1094N' 604 1800(The flux remains constant for constant field current)1800 113.4x1800Hence back e.m.f = {200-(3+ 0.2)× 7} V =177.6V(Since back emfis proportional to speed at constant flux]N,N' = E109 4 pm = 1865.8 rpm=1865 rpanN = N, x 1000 x177.6E109.4rpm = 897 rpm125At 125% of full load, load current = 40XA 50A1001983.5. a) A 120 V D.C. Shunt Motor having an armature resistance of 0.2 n and fieldresistance of 60 0, draws a line current of 40 A at full load, The brush voltage dropis 3 V and the rated full load speed is 1800 rpm. Calculate the speed at half loadand 125% of full load.(WBUT 2012)The armature current, I = 50-2= 48 AThe back emf= (120– 48x0.2-3)V=(120-9.6 –3)VE =107.4 VE Po_109.4N' 604 1800The relation between, where V, is thee current and , the[WBUT 2014]Answer:The relevant data for the D.C. shunt motor are listed below:Terminal voltageV =120 VI- 40AArmature resistancefihe flux remains constant for constant field current and terminal voltage)R, = 0.20R, = 602107.4x18001094 rpm = 1767 rpmR-20Field resistanceV = 120VRy = 602Line current= 40 ABrush voltage drop 3 VBEE-143

This question is from the D.C machine under we are going to find out the different parameters of D.C…

Answered: 34A shunt motor has a rated armature…

34A shunt motor has a rated armature current of 40A whe The rated speed of the motor is 1000 rpm. The armature resis the speed of the motor if total torque is reduced to 70% of tha

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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