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Question 44521

posted 10 months ago

A three phase, 10 pole, delta connected induction motor is supplied at440V, 50 Hz. It draws a current of 32A with a power factor of 0.81lagging. The motor runs at 575 RPM.
Total stator, Rotor copper and mechanical losses equate to 3, 4 and 7%of the input power. Determine each of the following:
The slip
The efficiency of the motor
The torque developed in the rotor
The shaft output torque.
Sketch and label the motor power flow chart for the motor described in this question. You answer must clearly identify the input power, output power and power losses.

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Question 44522

posted 10 months ago

A 3 phase STAR wound induction motor is supplied with a line voltage of400V at 60HZ. Each phase of the stator has 300 turns and the rotor is of the wound type with 200 turns. The Rotor windings have a resistance of100 and an inductance of 0.1H.
When the motor is stationary determine each of the following:
i The rotor EMF
ii The rotor frequency
The rotor current
- The power factor of the rotor

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Question 45030

posted 10 months ago

a) Sketch circuit diagrams showing field connections for the following self-excited generator d.c.generators. In addition connect the following self-excited generator by drawing the properconnections in the two terminal boxes

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Question 41769

posted 11 months ago

A de series motor is connected to a constant-torque load, which may be considered to require a constant electromagnetic torque regardless of motor speed. Neglect the voltage drops due to the armature and series-field resistances, the armature reaction, and the effects of saturation. (a) By what percent is the motor speed changed when the line voltage is reduced from 230 V to 200 V? (b) Repeat (a), assuming shunt motor. (c) State briefly what effects saturation might have on the answers to (a) and (b).Ans. (a) 13%; (b) *0

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Question 41768

posted 11 months ago

A 230-V shunt motor, having an armature resistance of 0.05 2 and a field resistance of 75 , draws Aline current of 7 A while running light at 1120 rpm. The line current at a given load is 46 A. Determine(a) the motor speed at the given load, (b) motor efficiency, and (c) total core and mechanical losses.Ans. (a) 1110.5 rpm; (b) 83.9%; (c) 903.9 W

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Question 42471

posted 11 months ago

A 50-Hz, two-pole, 750 kVA, 2300 V, three-phase synchronous machine hasa synchronous reactance of 7.75 2 and achieves rated open-circuit terminalvoltage at a field current of 120 A.
Calculate the armature-to-field mutual inductance.
The machine is to be operated as a motor supplying a 600 kW load at its rated terminal voltage. Calculate the internal voltage Eaf and the corresponding field current if the motor is operating at unity power factor.
c. For a constant load power of 600 kW, write a MATLAB script to plot the terminal current as a function of field current. For your plot, let the field current vary between a minimum value corresponding to a machine loading of 750 kVA at leading power factor and a maximum value
corresponding to a machine loading of 750 kVA at lagging power factor.What value of field current produces the minimum terminal current? Why?

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Question 42469

posted 11 months ago

55 A 460-V, 50-kW, 60-Hz, three-phase synchronous motor has a synchronous reactance of X, = 4.15 ohms and an armature-to-field mutual inductance,Laf = 83 mH. The motor is operating at rated terminal voltage and an input power of 40 kW. Calculate the magnitude and phase angle of the line-to-neutral generated voltage Êat and the field current Iț if the motor is operating at (a) 0.85 power factor lagging, (b) unity power factor, and (c) 0.85 powerfactor leading.

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Question 42472

posted 11 months ago

8 The manufacturer's data sheet for a 26-kV, 750-MVA, 60-Hz, three-phase synchronous generator indicates that it has a synchronous reactance X, =2.04 and a leakage reactance Xal = 0.18, both in per unit on the base. Calculate (a) the synchronous inductance in mH, (b) the armature leakage inductance in mH, and (c) the armature phase inductance La in m Hand per unit

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Question 42470

posted 11 months ago

6 The motor of Problem 5.5 is supplied from a 460-V, three-phase source through a feeder whose impedance is Zr = 0.084 + j0.82 ohms. Assuming the system (as measured at the source) to be operating at an input power of40 kW, calculate the magnitude and phase angle of the line-to-neutral generated voltage Eaf and the field current If for power factors of (a) 0.85lagging, (b) unity, and (c) 0.85 leading,

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Question 43076

posted 11 months ago

Propose two methods to control the torque of a D.C motor.Does it will effecting the material and cost? Write it in about30 words.

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