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
1.  What is a soil in an engineering context? Define. 2.  (a)  What is a clay? (b) What are the major properties and characteristics of clay? Discuss. (c)  Define the term

A counter flow heat exchanger is used to cool 2000kg/hr of oil(Cp= 2.5 KJ/Kg K) from 105 o C to 30 o C by the use of water entering at 15 o C. If the overall heat transfer coeff

Calculate the greatest stress - plate: A rectangular plate 10 mm thick within a hole of 50 mm diameter drilled on this is as shown in Figure 10. This is subjected to axial pul

(a) Show that the force exerted by a jet of water on an inclined fixed plate in the dissection of jet is given by fx = .a.v 2 . sin 2 θ. Where a is area of jet, v is velocity of j

Inspection of Tyres STEPS Both the tyres are checked for free rotation. Loose spokes are to be tightened. At the same time it is checked that the tyre is not dam

Ask question #MiThe steam that leaves the super-heater is expanded from 130bar at 535°C to 25.2bar at 310°C in a high pressure turbine. The steam from the exit of the HP turbine is

Example of Wedge friction: T wo blocks A and B are employed to raise load of 2000 N resting on another block C by the application of force P as shown in the figure g

Determine the relative error in the function y = ax 1 m1 x 2 m2 ........x n mn If u = 4x 2 y 3 / Z 4 and error in x, y, z be 0.a, compute the relative maximum error in u ta

ALUMINIUM Aluminium was first generated in year of 1825. Presently it is generated in quantity second only to steel. This is the most abundant metallic element on the crust of

show that the avogadro constant is the number of atoms in 0.072kg of carbon-12