6-20. A 208-V, six-pole, Y-connected, 25-hp design class B induction motor is tested in the laboratory, with the following results: No load: Locked rotor: dc test: 208 V, 24.0 A, 1400 W, 60 Hz 24.6 V, 64.5 A, 2200 W, 15 Hz 13.5 V, 64 A Find the equivalent circuit of this motor, and plot its torque-speed characteristic curve.

6-20. A 208-V, six-pole, Y-connected, 25-hp design class B induction motor is tested in the laboratory, with the following results: No load: Locked rotor: dc test: 208 V, 24.0 A, 1400 W, 60 Hz 24.6 V, 64.5 A, 2200 W, 15 Hz 13.5 V, 64 A Find the equivalent circuit of this motor, and plot its torque-speed characteristic curve.

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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A three-phase, 460-V, 60-Hz, four-pole Y-connected induction motor has the following equivalent circuit parameters: Rs = 0.42Ω, Rrʹ = 0.23Ω, Xs = Xrʹ = 0.82Ω, and Xm = 22Ω. The no-load loss 60W, may be assumed constant. The rotor speed is 1750 rpm. The rotational losses at this speed is 500W. Use the approximate equivalent circuit in figure below, to determine (a) the synchronous speed Ns; (b) the slip s; (c) the input current Ii; (d) the input power Pi; (e) the input PF of the supply, PFs; (f) the gap power Pg; (g) the rotor copper loss Pru; (h) the stator copper loss Psu; (i) the developed torque Td; (j) the efficiency; (k) the starting current Irs and starting torque Ts; (l) the slip for maximum torque sm; (m) the maximum developed torque in motoring, Tmm
A 440 V , 25 hp , 4 - pole , Y - connected three - phase wound - rotor induction motor has the following circuit parameters : R1 = 0.460 , R2 = 0.33 0 , x1 = 1.1 0 , x2 = 0.46 02 , and Xm = 25 22. ( stator referred ) Rotational losses ( including core loss ) = 500 W ( constant ) . If the terminal voltage and supply frequency are simultaneously reduced to 50 % , calculate the stator current , the developed air - gap torque , and the maximum torque at a slip of 0.04 .
A 50-kW, 440-V, 50-Hz, six-pole induction motor has a slip of 6 percent when operating at full-load conditions. At full-load conditions, the friction and windage losses are 300 W, and the core losses are 600 W. Find the following values for full-load conditions: (a) The shaft speed nm (b) The output power in watts (c) The load torque load in newton-meters (d) The induced torque ind in newton-meters (e) The rotor frequency in hertz
A 3-phase, 440-V, delta-connected, 4-pole 50-Hz induction motor runs at a speed of 1447 rpm when operating at its rated load. The equivalent circuit has the following per-phase :parametersr1=0.2 Ω, x1=x2'=2 Ω , r2'=0.4 Ω, rc=200 Ω , xɸ = 40 Ω Using the approximate circuit, determine, for rated load, the values of line current and power factor, torque, output power and efficiency. The mechanical loss is 1000 watts.
A 6-pole, 60-Hz, Y-connected, three-phase induction motor develops a torque (Td) of 250 N.m at a speed of 720 rpm. The rotor resistance is 0.4 Ohm/phase, and the stator winding impedance is negligible. A) What is the air-gap power? B) What is the rotor current refered to the stator? C) If the rotational loss is 1kW, what is the motor output power in hp?
)A 50-kW, 440-V, 50-Hz, six-pole induction motor has a slip of 6 percent when operating at full-load conditions. At full-load conditions, the friction and windage losses are 300 W, and the core losses are 600 W. Find the following values for full load conditions: (a) The shaft speed nm (b) The output power in watts (c) The load torque τload in newton-meters (d) The induced torque τind in newton-meters (e) The rotor frequency in hertz
A 20-hp, 3-phase, 400-V, 60-Hz 4-pole induction motor delivers full-load at5% slip. The mechanical rotational losses are 400W. Calculate the shaft torque
A 4-pole, 115 V, 60 Hz, 1710 rpm, capacitor-start single-phase induction motor has been designed to produce maximum starting torque per unit starting current. The motor has the following parameters: R1m=1.5ohms, X1m=2.6ohms, R1a=2.5 ohms, X1a=2.5 ohms, Xmag=40 ohms, R/2=1 ohms, X/2=1.6 ohmsNa/Nm =l, Capacitor in series with auxiliary winding = 375 μF.a) Draw the equivalent circuit for the motor under starting conditions. Determine the value of the starting torque.b) Draw the equivalent circuit for the motor when it runs at the rated (i.e., full load) speed. Determine the torque developed at this speed.c) Determine the ratio of the starting torque to the torque developed at the rated speed.
18. A single-phase, 120 V, 60 Hz, four-pole, split-phase induction motor has the following standstill impedances:Main winding: Zm =5+j6.25Auxiliary winding: Za =8+j6a) Determine the value of capacitance to be added in series with the auxiliary winding to obtain maximum starting torque.b) Compare the starting torques and starting current with and without the added capacitance in the auxiliary winding circuit when operated from a 120V, 60Hz supply.
A 440V, 50 Hz, 6 pole, Y-connected induction motor is rated at 75 kW. The equivalent circuit parameters are R1 Ω =0.082 Ω R2 = 0.070 Ω XM = 7.2 Ω X1 Ω =0.19 Ω X2 = 0.180 Ω In this problem, you are to calculate the pull-out torque. The slip is 0.04. a) Rth and Vth? b) Slip at pullout torque Smax? c) The pullout torque Tmax?
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 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 total stator losses amount to 1000 W, evaluate the efficiency of the motor at this load.