3. A 12-pole, 420 V, 10 kW, 50 Hz, three-phase induction motor gave the following test results. Voltage (V) Current (A) 6.7 Power (W) 500 (including 230W Open-circuit test 420 mechanical loss) 980 Locked-rotor test 99 14.0 (a) Calculate the parameters of the per-phase equivalent circuit assuming a star-connected stator winding. (b) Determine the torque, output power, input line current, power factor and efficiency if the machine operates with a slip of 0.03. (c) If the stator winding is actually connected in delta what would be the value of resistance per-phase obtained from direct measurement?

3. A 12-pole, 420 V, 10 kW, 50 Hz, three-phase induction motor gave the following test results. Voltage (V) Current (A) 6.7 Power (W) 500 (including 230W Open-circuit test 420 mechanical loss) 980 Locked-rotor test 99 14.0 (a) Calculate the parameters of the per-phase equivalent circuit assuming a star-connected stator winding. (b) Determine the torque, output power, input line current, power factor and efficiency if the machine operates with a slip of 0.03. (c) If the stator winding is actually connected in delta what would be the value of resistance per-phase obtained from direct measurement?

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...

See similar textbooks

Similar questions

A 25 HP, 6 pole, 50 Hz, 3-phase slip ring induction motor runs at 960revolutions per minute on full load with a rotor current per phase of 35 A.Allowing 250 W for the copper loss in the short-circuiting gear, and 1000Wfor mechanical losses, find the resistance per phase of the three-phaserotor winding.
The rotor resistance and reactance of a squirrel-cage induction motor rotor atstandstill are 0.14 ohm per phase and 0.8 ohm per phase respectively. Assuminga transformer ratio of unity, from the eight-pole stator having a phase voltage of254 at 60 Hz to the rotor secondary, calculate the followingA. rotor starting current per phase.B. the value of slip producing maximum torque.
(b) 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
Open circuit tests carried out on a 3.5 MVA, 4.16 kV, 60 Hz, three phase star connected synchronous generator gave the following results:If (A):1015202530EL (kV):3.54.165.76.257.95In the short circuit test a field current of 20A was needed to circulate full load current. The armature winding resistance is 1.2Ω /phase, the field winding resistance is 500 Ω and the rotational loss is 250kW. Determine the power angle, the voltage regulation and the efficiency when the generator delivers rated load at terminal voltage of 4.4 kV and at 0.8 power factor leading.Draw the power flow diagram for the generator and include all values of power flows.
A 70-MVA, 69.3-kV, three-phase round-rotor synchronous generator has a synchronous reactance of 14 ohm per phase and negligible armature resistance. 1) The generator is delivering rated power at 0.87 power factor lagging at the rated terminal voltage to an infinite bus bar (Fig. 1). Determine the magnitude of the generated emf per phase and the power angle δ. 2) The generator is delivering 53.5 MW to the bus bar at the rated voltage with its field current adjusted for a generated emf of 46 kV per phase. Determine the armature current and the power factor. Is the power factor is lagging or leading? 3) Given that the generator is operating at the excitation voltage of Part (1), determine the maximum steady-state power which the machine can deliver without losing synchronism. Find the armature current corresponding to this maximum power.
Q. A 3-phase, star connected, 10 kVA, 400 V, salient pole alternator with direct and quadrature axis reactances of 15 ohm and 8 ohm respectively, delivers full-load current at 0.8 power factor lagging.Neglect the armature resistance. Solve this question to chose the correct answer for the following: The direct axis and quadrature axis components of armature current are ........ and ......... respectively ?
The primary leakage impedance and equivalent secondary impedance referred to stator atstandstill of a 3-phase, 220 V, 50-Hz, 4-pole induction motor are (0.4 + 3j)ohms and (1.2 + j1) ohms per phaserespectively. If the magnetizing current is neglected, determine the maximum torque the motor candevelop and slip at which it occurs.
A 75kW, 440V, 3-phase, 6-pole,50Hz wound rotor induction motor has a full load slip of0.04 and the slip at maximum torque of 0.2 when operating at rated voltage and frequencywith rotor winding short circuited at the slip rings. Assume the stator resistance androtational losses to be negligible. Find(a) Maximum torque(b) Starting torque(c) Full load copper loss.The rotor resistance is now doubled by adding an external series resistance.Determine(d) Slip at full load(e) full-load torque(f) slip at maximum torque
A 20KW, 440V, short shunt compound dc generator has full load efficiency of 87%. If the resistance of the armature and interpoles is 0.4ohm and that of the series and shunt fields 0.25ohm and 240ohms respectively, calculate the combined bearing friction, windage and core loss of the machine A 10 kW 250 volts self-excited generator, when delivering rated load, has an armature-circuit voltage drop of 5% of the terminal voltage and a shunt field current equal to 5% of the rated load current. The resistance of the armature is 0.02 ohm. Calculate the voltage generated and power output.
The full load slip of a 4-pole, 60Hz, 440V (line-to-line) three phase induction motor is 0.05. (i). What is the speed of the rotating stating? What is the frequency (in Hz) of the rotor current? (ii). When the output power of the motor is 90 hp at a speed of 1732 rmp, rotational losses (which include frictional and core losses) are 10,100W, while copper losses for both the rotor and stator total 3700W. Determine the motor efficiency and line current, assuming the motor has a 0.8pf lagging under the conditions.
A 3-phase, 50-Hz, 415V, Y-connected, 4-pole, squirrel-cage rotor induction motor, has a per-phase of rotor winding impedance of 0.015+j0.08Ω. Assuming that the stator winding impedance is negligible, determine the following; i) The maximum slip, smax ii) The maximum pull-out torque, τmax iii) The required starting torque, τstart iv) The external resistance that should be added in series with rotor resistance if ratio between starting torque and the maximum torque should be 0.85
A 220 V, single-phase induction motor gave the following test results:Blocked-rotor test: 120 V, 9.6 A, 460 WNo-load test: 220 V, 4.6 A, 125 WThe stator winding resistance is 1.5 Ω, and during the blocked-rotor test, the starting winding is open. Determine the equivalent circuit parameters. Also, find the core, friction and windage losses.