Induction machine operation, Mechanical Engineering

Induction Machine Operation

For operation with rated L-L voltage of 230 V and rated frequency of 60 Hz, the performance of a particular 10 hp machine at its rated speed and power is:

Speed = 1750 rpm I1 = 24.5 A rms Pin = 7.93 Kw T = 40.7 Nm Pout = 7.46 Kw

S = 0.0277 Cos è = 0.811 Pg = 7.67 Kw I2

2R2 = 212w eff = 94.1 %

a) One important parameter change for efficiency improvement is to reduce the value of R2. Determine the new values of the quantities above for a second identical machine except that R2 is 1/2 as large and the machine is operated at 1/2 the slip (so R2/S = constant). This is a "thinking question", the answers can be obtained with only minimal calculation (many are unchanged) by reasoning guided by the equivalent circuit. Don't make it hard or long.

R2new = (1/2) R2

Slip = __0.01385___ Po = ___________ hp

Speed = ______ RPM cos è = _________

I1 = ___________ A Pg = ___________ w

Pin = ___________ w I2R2 = _________ w

T = ___________ Nm eff = ___________ %

b) The equivalent circuit parameters of the above10 hp, 230 V (rms L-L), 60 hz, 4 pole, three phase induction motor are:

r1 = 0.140Ù x1 =0.650Ù xm = 12.0Ù

r2 = 0.157Ù x2 = 0.650Ù Neglect core loss

Use the equivalent circuit to find the input current and developed torque at rated voltage and frequency and a slip of S = 0.01385 (1/2 rated slip). As a first approximation I1 and T were shown to be linear functions of slip. Compare your results with 50% of the rated slip values as listed below.

Equiv Ckt @ S= 0.5 SR 50% of Rated Values

I1 = _________ A I1 = __12.25__ A

T = _________ Nm T = ___20.35__ Nm

Induction Machine Operation

c) Evaluate the motor performance at 15 hz with constant volts/hz and at the same slip frequency as in part a (S = 4 x 0.0277 = 0.1108) neglecting R1). Recall that, without stator resistance, the current, torque and power factor are the same as the rated values given in part a, only the powers vary.

Optional: Include R1 This requires an equivalent circuit calculation.

R1 = 0 (25 points) R1 ≠ 0

I1 = ___________ A I1 = ___________ A

Pin = ___________ w Pin = ___________ w

T = ___________ Nm T = ___________ Nm

Po = ___________ hp Po = ___________ hp

cos è = _________ cos è = _________

Pg = ___________ w Pg = ___________ w

I2R2 = _________ w I2R2 = _________ w

d) Test s show the starting current and torque of a (different than in part a) motor to be

I = 6 x IR A T = 1.5 x TR Nm at rated voltage V = VR

Use this starting performance data to find the voltage ratio (Vo/Vin )of a transformer which when placed between the motor and the source Vin = VR will limit the transformer input side starting current to = 2 x IR A.

What is the torque and motor side current as multiples of rated values of when using this motor starting transformer? Hint: At starting, (S = 1) the motor is simply an impedance. (25 points)

Vo/VR = _________

I1 = ______ x IR

T = ______ x TR

Posted Date: 3/16/2013 3:39:53 AM | Location : United States







Related Discussions:- Induction machine operation, Assignment Help, Ask Question on Induction machine operation, Get Answer, Expert's Help, Induction machine operation Discussions

Write discussion on Induction machine operation
Your posts are moderated
Related Questions

Explain the Creation Phase of radial drilling machine Objective:  "To generate alternative methods for providing the function, through creative thinking, brainstorming and

The wing of a light, single-engine general aviation aircraft has an area of 15.8 m 2 and a span of 9.6 m. The airfoil of the wing is NACA 65-415, which has a lift slope of 0.1033

Internal Energy (U): It is the energy possessed by the system on account of its configurations, and motion of atoms and molecules. Not like potential energy and kinetic energy

Working of stream engine: The high pressure steam from boiler is supplied to the steam chest. The high pressure steam enters cylinder through inlet port and exerts pressure on

Phase 1 Initially ALL Valves A, B, C, D, E and F are closed.  ALL Tanks A, B, C, D, E are separated and each sealed from the atmosphere. Tank E initially has 2' of air @

Necessity of Suspension System Not to transmit road shocks to the motorcycle components. To guard the driver from road shocks and to make sure the stability of the ve


Determine the shape of the beam: A simply supported beam of span l carries a concentrated load P at midspan. If the beam is to be a beam of consistent strength, determine the

Loosening a Part with Multiple Fasteners: Loosening a part with multiple fasteners should be done from the outside to inside in a criss-cross pattern, loosening the small fastener