12:57 €←EE21A-assignment1.pdfClass: EE21ADC GENERATORSUNIVERSITY OF SOMALIA (UNISO)Course: Electrical machinesAssignment 1Date: 30/03 2023Solve the following problems1. A 4-pole, D.C. generator has a wave-wound armature with 792 conductors. The flux per pole is 0.0121Wb. Determine the speed at which it should be run to generate 240 V on no-load. [751.3 r.p.m.]...| ...| 77% i2. A 20 kW compound generator works on full-load with a terminal voltage of 230 V. The armature, seriesand shunt field resistances are 0.1, 0.05 and 115 2 respectively. Calculate the generated e.m.f. when thegenerator is connected short-shunt. [243.25 V]3. A d.c. generator generates an e.m.f. of 520 V. It has 2,000 armature conductors, flux per pole of 0.013Wb, speed of 1200 r.p.m. and the armature winding has four parallel paths. Find the number of poles. [4]DC MOTORS4. When driven at 1000 r.p.m. with a flux per pole of 0.02 Wb, a D.C. generator has an e.m.f. of 200 V. Ifthe speed is increased to 1100 r.p.m. and at the same time the flux per pole is reduced to 0.019 Wb per pole,what is then the induced e.m.f.?[209 V]5. Calculate the flux per pole required on full-load for a 50 kW, 400 V, 8-pole, 600 r.p.m. D.C. shuntgenerator with 256 conductors arranged in a lap-connected winding.The armature winding resistances is 0.12, the shunt field resistance is 200 £2 and there is a brush contactvoltage drop of 1 V at each brush on full load.[0.162 Wb]6. A short-shunt compound d.c. Generator supplies a current of 100 A at a voltage of 220 V. If the resistanceof the shunt field is 50 £2, of the series field 0.025 02, of the armature 0.05 £2, the total brush drop is 2 V andthe iron and friction losses amount to 1 kW, find(a) the generated e.m.f. (b) the copper losses (c) the output power of the prime-mover driving the generatorand (d) the generator efficiency.[(a) 229.7 V (b) 1.995 kW (c) 24.99 kW (d) 88%]UNIVERSITY OF SOMALIA (UNISO)Solve the following problems1. d.c. motor connected to a 460-V supply takes an armature current of 120 A on full load. If thearmature circuit has a resistance of 0.25 £2, calculate the value of the back e.m.f. at this load.[430 V]2. A 4-pole d.c. motor takes an armature current of 150 A at 440 V. If its armature circuit has aresistance of 0.15 02, what will be the value of back e.m.f. at this load? [417.5V]3. Calculate the torque in newton-metre developed by a 440-V d.c. motor having an armature resistanceof 0.25 £2 and running at 750 r.p.m. when taking a current of 60 A.[325 N-m]4. A 4-pole, lap-connected d.c. motor has 576 conductors and draws an armature current of 10 A. If theflux per pole is 0.02 Wb, calculate the armature torque developed. [18.3 N-m]5. A 4-pole 250-V, D.C. series motor has a wave-wound armature with 496 conductors.Calculate (a) The gross torque (b) the speed (c) the output torque and(d) The efficiency, if the motor current is 50 A8The value of flux per pole under these conditions is 22 mWb and the corresponding iron, friction anwindage losses total 810 W. Armature resistance - 0.19 22, field resistance = 0.14 2.[(a) 173.5 N-m (b) 642 r.p.m. (c) 161.4 N-m (d) 86.9%]6. AD.C. serieor on full-load takes 50 A from 230Vdc mains. The total resistance of the motor 0.22 2. If theiron and friction losses together amount to 5% of the input, calculate the power delivered by the motor shaft. Total

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Solve the following problems 1. A 4-pole, D.C. generator has a wave-wound armature with 792 conductors. The flux per pole is 0.0121 Wb. Determine the speed at which it should be run to generate 240 V on no-load. [751.3 r.p.m.]

Solve the following problems 1. A 4-pole, D.C. generator has a wave-wound armature with 792 conductors. The flux per pole is 0.0121 Wb. Determine the speed at which it should be run to generate 240 V on no-load. [751.3 r.p.m.]

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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