Induction machine operation, Mechanical Engineering

Assignment Help:

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


Related Discussions:- Induction machine operation

What do you understand by straight line mechanism, What do you understand b...

What do you understand by straight line mechanism ? Describe with a neat sketch the working and construction of any three types of straight line mechanism. Derive a mathematical

Plc, proportional controller for lube oil temperature of engine working dia...

proportional controller for lube oil temperature of engine working diagram

Heat removal factor, 1.Calculate the heat-removal factor for a collector ha...

1.Calculate the heat-removal factor for a collector having an overall heat-losscoefficient of 6 W/m2K and constructed of aluminum fins and tubes. Tube-to-tube centered distance is

Shielded metal arc welding (smaw), SHIELDED METAL ARC WELDING (SMAW) It...

SHIELDED METAL ARC WELDING (SMAW) It also known as Manual Metal Arc Welding (MMAW). The heat required for welding is generated by the electric arc formed between metallic elect

Hinged support, Hinged Support: Hinged (Pin) Support: At hinged end,...

Hinged Support: Hinged (Pin) Support: At hinged end, beam cannot move in any direction support will not develop any resisting moment, but it can develop reaction in any of t

Explain the statement- subsidence of the ground, Explain the statement- su...

Explain the statement- subsidence of  the ground Another type of problem is the subsidence of  the ground due to breakdown of weak rocks like  limestone, soluble rocks (gypsum

Second gear position- shifting of gear, Second Gear Position: When ge...

Second Gear Position: When gear M2 on the main shaft is in mesh with gear C2 on the countershaft then this is known as second gear position. To rotate free gear M2 with the m

Thermodynamics, when does water convert in to ice at vaccum pressure

when does water convert in to ice at vaccum pressure

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd