380 V, 60 Hz, Star connected, 870 r.p.m., Eight poles, Three-Phase Induction Motor has the following per phase parameters: R1 = 0.07, R2 = 0.05, X1 = X2 = 0.2, Xm = 6.5, Draw the exact equivalent circuit and determine the following: Power Factor VI. Input Power VII. Rotor Current VIII. Magnetizing Current IX. Stator copper loss X. Rotor copper loss

380 V, 60 Hz, Star connected, 870 r.p.m., Eight poles, Three-Phase Induction Motor has the following per phase parameters: R1 = 0.07, R2 = 0.05, X1 = X2 = 0.2, Xm = 6.5, Draw the exact equivalent circuit and determine the following: Power Factor VI. Input Power VII. Rotor Current VIII. Magnetizing Current IX. Stator copper loss X. Rotor copper loss

Electric Motor Control

10th Edition

ISBN:9781133702818

Author:Herman

Publisher:Herman

Chapter33: Four-speed, Two-winding (consequent Pole) Motor Controllers

Section: Chapter Questions

Problem 7SQ: Why are different motor connections shown for what appears to be the same motor in the various...

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Why are different motor connections shown for what appears to be the same motor in the various diagrams in Figure 332? FIG. 332 Typical arrangements for four-speed, three-phase, two-winding motors.
A 110-V, 50-Hz single phase induction motor (split -phase) has the following constants for the main and auxiliary windings: Main winding, Zm (1.2 +j 25) ohm and auxiliary winding, Z,= (12+j 5) ohm. Determine (i) total current and power factor currents at time of starting, and (ii) phase angle between the main winding current and starting winding current.
A four-pole, single-phase, 120 V, 60 Hz induction motor gave the following standstill impedances when tested at rated frequency:Main winding : Zm =1.5+j4 ohmsAuxiliary winding : Za =3+j6 ohmsa) Determine the value of external resistance to be inserted in series with the auxiliary winding to obtain maximum starting torque as a resistor split-phase motor.b) Determine the value of the capacitor to be inserted in series with the auxiliary winding to obtain maximum starting torque as a capacitor-start motor.c) Determine the value of the capacitor to be inserted in series with the auxiliary winding to obtain maximum starting torque per ampere of the starting current as a capacitor-start motor.d) Compare the starting torques and starting currents in parts (a), (b), and (c) expressed as per unit of the starting torque without any external element in the auxiliary circuit, when operated at 120V, 60Hz.
A 460 V, 60 Hz, Star connected, 870 r.p.m., Eight poles, Three-Phase Induction Motor has the following per phase parameters: R1 = 0.07, R2 = 0.05, X1 = X2 = 0.2, Xm = 6.5, Draw the approximate equivalent circuit and determine the following:I. Starting TorqueII. Maximum TorqueIII. Rated TorqueIV. Stator CurrentV. Power FactorVI. Input PowerVII. Magnetizing Current
Calculate and plot the torque-speed characteristics for a four-pole induction motor. Themotor parameters are rs = 24.5 Ω, rr =23 Ω, Xs = 10 Ω, Xr = 40 Ω, and Xm = 25 Ω. Therated voltage is 110 V. The maximum frequency of the supplied phase voltages is fmax =60 Hz. Assume the phase voltages are supplied with frequencies 20, 40 and 60 Hz. ...
17. A single-phase, 120 V, 60 Hz, four-pole, split-phase induction motor gave the following blockedrotor test data:VIP Main winding 32 4 80Auxiliary winding 40 4 128a) Determine the standstill impedances of the main and auxiliary windings.b) Determine the values of the resistances to be added in series with the auxiliary winding to obtain maximum starting torque.c) Compare the starting torques and starting currents with and without the added resistance in the auxiliary winding circuit if the motor is connected to a 120 V, 60 Hz supply
The no-load and locked-rotor test results of a three-phase 10 HP, 220 V, 60 Hz, 6 poles star connected induction motor are; The no-load test: VNL=220 V, PNL=340 W, INL=6.2 A The locked-rotor test: VSC=54 V, PSC =430 W, ISC =15.2 A The voltage across the stator windings is 2 V when nominal DC current flows through it. Coefficient for DC resistance is 1,25. a) Calculate the equivalent circuit parameters and draw the complete single-phase equivalent circuit of the induction motor. b) Calculate efficiency of the motor for s=0.06 by using the approximate equivalent circuit (RFe core resistance is not ignored). c) Shaft torque for s=0,06 d) Slip value at the maximum (breakdown) torque, e) Maximum (breakdown) torque of the induction motor. f) Speed of the motor at maximum torque point. g) Rotor frequency at maximum torque.
Q2. For a 10 kW, 380V, three-phase, four-pole, 1200 r/min, delta-connected induction motor. Adopt a specific magnetic loading of 0.4712 Wb/m2 and a specific electric loading of 23000 ampere-conductors per metre. The motor has a full-load efficiency of 85% and a full-load power factor of 0.8. A square pole design may be assumed and the stator leakage impedance voltage drop may be ignored. Assume also that the winding is full-pitched and uniformly wound. To calculate the following design parameters (a) The approximate outer diameter and length of the rotor core (b) the air gap length of the motor (c) the turns per phase (d) the number of conductors per slot, if 3 slots per pole per phase are chosen
1.Show that if three phase currents, each of equal magnitude and differing in phase by 120degree, flow in a three phase winding that are 120 degree apart from each other then it willproduce a rotating magnetic field of a fixed magnitude. 2. A three phase, 5-hp, 60Hz, 115V, 4-pole induction motor is operating at rated voltage, rated frequency, and 125 percent rated load has an efficiency of 85.4 percent. The stator conductor loss, rotor copper loss and core loss are 223.2W, 153W, and 114.8W respectively.Sketch the power flow diagram, enter the given data, and determine i) shaft speed ii) shaft torque 3. Can single phase induction motor be self-started? Explain the operation of a split phase single phase induction motor?
A three-phase, 60-Hz induction motor runs at 890 r/min at no load and at 840 r/min at full load. (a) How many poles does this motor have? (b) What is the slip at rated load? (c) What is the speed at one-quarter of the rated load? (d) What is the rotor’s electrical frequency at one-quarter of the rated load?
(b) A 415V, 50Hz, delta-connected, 4-pole, squirrel cage induction motor has a perphase equivalent circuit as shown in Figure Q4(b). The circuit parameter values (in Ω/phase) for the stator is as follows: R1 = 0.095 Ω ; R2 = 0.06 Ω; X1 = 0.68 Ω ; X2 = 0.67 Ω; Xm = 18 Ω The motor is running at 1400 rpm at full-load. The core loss of the motor is assumed to be zero. The total friction and windage losses is 600 W, independent of load. Determine the efficiency of the motor.
Plot the V curves (no load, partial loads and full load) for a 7.2 kW, 208 V, three phase, star connected synchronous motor by varying the power factor from 0.5 lagging to 0.5 leading. The synchronous reactance of the motor is 4Ω/phase and the winding resistance is negligible. Assume Ea= 100 Ifwhere Ifis the field winding current