A 180-V, DC motor is connected as a cumulatively-compounded DC motor. Its characteristics are given below: RA=0.1092 NF 1000 turns Answer The efficiency is : % Rs = 0.05 2 NSE = 10 turns RF = 125 92 IL, rated = 55 A This motor has compensating windings and interpoles. When the motor is rotating at 1680 RPM, 180 V supply, 52 A armature current, the rotational losses are 933 Watt. What is the efficiency of this motor? Radj = 100 2 nm 1800 RPM

A 180-V, DC motor is connected as a cumulatively-compounded DC motor. Its characteristics are given below: RA=0.1092 NF 1000 turns Answer The efficiency is : % Rs = 0.05 2 NSE = 10 turns RF = 125 92 IL, rated = 55 A This motor has compensating windings and interpoles. When the motor is rotating at 1680 RPM, 180 V supply, 52 A armature current, the rotational losses are 933 Watt. What is the efficiency of this motor? Radj = 100 2 nm 1800 RPM

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

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A 180-V, DC motor is connected as a cumulatively-compounded DC motor. Its characteristics are given below: RA = 0.10 2 Rs = 0.05 2 RF = 125 2 Radj = 100 2 NF = 1000 turns NSE= 10 turns IL, rated = 55 A Nm=1800 RPM This motor has compensating windings and interpoles. When the motor is rotating at 1680 RPM, 180 V supply, 52 A armature current, the rotational losses are 933 Watt. What is the efficiency of this motor? Select one: O a. % Efficiency = 74.5 % O b. % Efficiency = 84.4 % O c. None O d. % Efficiency = 94.2 %
A 40-HP, 230-V., 8-pole, 25 Hz three-phase induction motor is running at 355 rpm at rated load. The torque lost by friction is 24 N-m. If the stator losses amount to 1,000 W., calculate the efficiency of the motor at this load.
A 220-V-rms (line-to-line), 60-Hz, three-phase induction motor operates at 3500 rpm while delivering its rated output power of 3 hp. The line current is 8 A rms and the losses are 300 W. Find the input power, power factor, and efficiency.
A 440-V-rms (line-to-line voltage) three-phase induction motor runs at 1150 rpm driving a load requiring 15 Nm of torque. The line current is 3.4 A rms at a power factor of 80 percent lagging. Find the output power, the power loss, and the efficiency.
A 25-hp three-phase induction motor operates for a 440-Vrms (line-to-line) three phase source and draws a line current of 35 A rms at a power factor of 83 percent lagging under rated full load conditions. The full load speed is 1750 rpm. Under no load conditions the speed is 1797 rpm and the line current is 6.5 A rms at a power factor of 30 percent lagging. Find the power loss and efficiency with full load, the input power with no load and the speed regulation.
A 240-V, 100 A armature full-load line current, 1500 RPM, cumulatively-compounded DC motor is considered in this problem. Its characteristics are given below: RA + Rs = 0.20N RF = 140 N Radj = 160 N NF = 2000 turns NSE = 8 turns This motor has compensating windings and interpoles. The magnetization curve for this motor at 1500RPM is shown in a tabular form below: | 0.1 0.2 0.4 0.5 0.6 0.8 1.0 | 1.2 1.6 1.8 2.0 2.2 2.4 If,A EA,V | 6.0 25 | 50 | 110| 135 160 205 | 235 255 | 275 | 285 288 | 290 291 What is the full-load speed of this motor? Select one: O a. Full-load speed n = 1294 RPM O b. Full-load speed n = 1739 RPM O c. Full-load speed n = 1610 RPM O d. None
Consider a separately-excited DC motor with an armature resistance RA= 0.25 N and terminal voltage VT= 120 V. The motor rated speed is 1800 RPM. The field winding supply VF= 36 V and the field resistance is adjustable. The motor has compensating windings and interpoles. IF (A) EA (V) 0.3 85 These values were taken at speed n=1800RPM 0.0 0.1 0.2 0.4 0.5 0.6 0.7 0.8 30 60 102 115 124 130 134 If the motor is driving a load at rated armature current Ia = 46 A, with Radj + Rf=1202. Find the speed of rotation of the motor in RPM. Select one: O a. None O b. Speed n = 1410 RPM O c. Speed n = 1800 RPM O d. Speed n = 2298 RPM
A three-phase induction motor is rated at 5 hp, 1760 rpm, with a line-to-line voltage of 220 V rms. The motor has a power factor of 80 percent lagging and an efficiency of 75 percent under full-load conditions. Find the electrical input power absorbed by the motor under full-load conditions. Also, find the rms line current.
A series-connected dc motor operates at 1400 rpm from a source voltage of VT=75 V. The developed torque (load torque plus loss torque) is constant at 25 Nm. The resistance is RA+RF=0.1 Ω. Determine the value of resistance that must be placed in series with the motor to reduce the speed to 1000 rpm.
A 40Hp, 230V, 10pole, 50Hz three-phase induction motor is running at 585 rpm at rated load. If the stator loss amounts to 1000W and the efficiency of the motor at this load is 90%. Determine the torque lost by friction in lb-ft
A certain four-pole 240-V-rms 60-Hz delta-connected three-phase induction motor has Rs=1 ΩRr′=0.5 Ω Xs=1.5 ΩXr′=0.8 Ω Xm=40 Ω Under load, the machine operates at 1728 rpm and has rotational losses of 200 W. Neglecting the rotational losses, find the no-load speed, line current, and power factor for the motor.
A 208 V, 60 Hz, 2-pole, Y-connected induction motor is rated at 16 hp. Its equivalentcircuit components have the following values:(R1 = 0.200 ohm, X1 =0.410 ohm); (R2 = 0.120 ohm, X2 = 0.410 ohm); Xm = 15.0 ohm.Rotor slip is 4.5% at the rated voltage and frequency. Mechanical and core losses are 230Wand 200W respectively. Find (a) rotor speed (b) line current and motor p.f (c) Air-gap andconverted power (d) Induced torque.