HomeworkLib
Question

Consider a 50 kW, 3-phase, 380 V line-to-line, 50 Hz, 6 pole Y-connected wound-rotor induction motor....

Consider a 50 kW, 3-phase, 380 V line-to-line, 50 Hz, 6 pole Y-connected wound-rotor
induction motor. The stator winding ac resistance is 0.1 Ω/phase. The effective stator-to-rotor turns
ratio is 2. The exciting branch is negligible.
It is found that when an external resistor of 0.09 Ω/phase is connected to the rotor terminals maximum
starting torque of 1150 Nm is obtained.
a. Compute the internal mechanical power and the internal torque developed by this motor when it
drives a load at a speed of 950 rpm with the rotor terminals are short circuited (normal motor
operation). (17 pts)
b. Suppose that constant V/f ratio control is used to control the speed of this motor. Find the frequency
at which maximum torque is obtained at starting without connecting any external resistances to the
rotor (18 pts)

engineering   Electrical-Engineering   
0 0
Add a comment Improve this question Transcribed image text
Next > < Previous
Sort answers by oldest

Homework Answers

Answer #1

& Given question P= 50kw, U = 380v, f-50HZ, P=6, Rilph = o.Inph, Stator Potor =2, Re = 0.99948 I manset: 11 SUNM la We know rTem SNs (Us, No em (Nsq Nr) stad O OSX1000 - TmanStat Ng-950 Nse 950 11417 so 1150 Ny 950 Nse-lus:90 120xf2 = 1451.30 P 120xfIn question additional resistance in rotor circuit will make maximum torque at starting , to get same maximum torque with out external resistance with V/f control method by changing frequency and maintain V/f= constant.required frequency is obtained.

0 0
Add a comment
Know the answer?
Add Answer to:
Consider a 50 kW, 3-phase, 380 V line-to-line, 50 Hz, 6 pole Y-connected wound-rotor induction motor....
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Log In

Sign Up

Not the answer you're looking for? Ask your own homework help question. Our experts will answer your question WITHIN MINUTES for Free.
Similar Homework Help Questions

  • A 3-phase, 460 V, 1740 rpm, 60 Hz, 4-pole wound-rotor induction motor has the following parameters...

    A 3-phase, 460 V, 1740 rpm, 60 Hz, 4-pole wound-rotor induction motor has the following parameters per phase: R1 = 0.25 Ω, ' 2R = 0.2Ω, ' 1 2 X = X = 0.5Ω, 30 m X = Ω. The rotational losses are 1700 W. With the rotor terminals short-circuited, find: 1. at starting: • current when started direct on full voltage, • a torque 2. at full load: • slip • current • ratio of starting current to full-load...

  • A 3 phase, 440 V, 6 pole, 970 rpm, 50 Hz, Y-connected induction motor has the...

    A 3 phase, 440 V, 6 pole, 970 rpm, 50 Hz, Y-connected induction motor has the following parameters referred to the stator Rs = 0.2 Ω, Rr'一0.15 Ω, xs-x-= 0.4 Ω The stator to rotor turns ratio is 3.5 The motor speed is controled by the Static Scherbius Drive. The drive is designed for a speed range of 30% below the synchronous speed. The maximum value of firing angle is 170'. Calculate (i) Turns ratio of the transformer (ii) Torque...

  • -23 An 8-pole, 230-V, 60-Hz, A-connected, three-phase induction motor has a rotor impedance of 0.025 +...

    -23 An 8-pole, 230-V, 60-Hz, A-connected, three-phase induction motor has a rotor impedance of 0.025 + 0.112/phase. The stator winding impedance is negligible. Determine (a) the speed at which the motor develops the maximum torque, (b) the maximum torque of the motor, and (c) the start- ing torque as a percentage of maximum torque. What additional resistance must be inserted in the rotor circuit to make the starting torque equal to 75% of the maximum torque?

  • 4. A three-phase induction motor has the following data: Nominal power, P 7.5 kW Nominal voltage, = 400 V Connection: Y Nominal frequency, f-50 Hz Nominal speed, nn 960 rpm Stator resistance, r,...

    4. A three-phase induction motor has the following data: Nominal power, P 7.5 kW Nominal voltage, = 400 V Connection: Y Nominal frequency, f-50 Hz Nominal speed, nn 960 rpm Stator resistance, r, 0.55 Ω Rotor resistance referred to a stator winding phase: r:-0.51 Ω Stator leakage inductance, L,-4.4 mH Rotor leakage inductance referred to a stator winding phase,1'-4.4 mH Magnetising inductance L-65 mH How many pole pairs has the motor? 12] a. Calculate the nominal power factor of the...

  • A 500 hp, three-phase, 2200 V, 60 Hz, 12-pole, Y-connected, wound-rotor induction motor has the following...

    A 500 hp, three-phase, 2200 V, 60 Hz, 12-pole, Y-connected, wound-rotor induction motor has the following parameters: 5.9 0.225 Ω x, R, R',-0.235 Ω X, 31.8 Ω R""-780 Ω 1.43 Ω Calculate the following: a. Slip at maximum torque b. Input current and power factor at maximum torque c. Maximum torque d. Resistance that must be added to the rotor windings (per phase) to achieve maximum torque at starting

  • 5. A 208-V four-pole 60-Hz Y-connected wound-rotor induction motor is rated at 30 hp. Its equivalent...

    5. A 208-V four-pole 60-Hz Y-connected wound-rotor induction motor is rated at 30 hp. Its equivalent circuit components are R=0.100 Ry=0.070. X - 10.00 R = 250 X; -0.2100 X=0.21002 Praw=500 W P =0.5% of input at full load For a slip of 0.05, find (a) The line current (b) The induced voltage in the rotor (c) The stator power factor (d) The rotor power factor (e) The rotor frequency (f) The stator copper losses (g) The core loss (h)...

  • A 230 V, 50 Hz, three-phase, Y-connected, 6-pole induction motor has the following per-phase parameters R-0.07...

    A 230 V, 50 Hz, three-phase, Y-connected, 6-pole induction motor has the following per-phase parameters R-0.07 Ro 00 0.08 Ω x, x, 0.3 xm 6.33 At a slip of 2%, determine the followings using approximate equivalent circuit of the motor i) The motor speed in rev/min and rad/s. ii) The rotor current. ii) The stator current. iv) The induced torque. v) The efficiency of the motor.

  • The equivalent circuit of a 440 V, 3-phase, 8 pole, and 50 Hz star-connected induction motor (HELP)

    Question:  The equivalent circuit of a 440 V, 3-phase, 8 pole, and 50 Hz star-connected induction motor is shown in figure 1. The short-circuit test is conducted with a locked rotor and a line current of 80 A. The open-circuit test is conducted by supplying the stator winding at rated voltage and at the rotor is rotating freely without any mechanical load.           Fig. 1 The per-phase equivalent circuit of a 3-phase induction motora)  Determine the line voltage and power factor on the...

  • 5 Marks) A 4-pole, 3 phase, 50 Hz, 230 V induction motor. Each phase of rotor winding b) has one-fourth the number of t...

    5 Marks) A 4-pole, 3 phase, 50 Hz, 230 V induction motor. Each phase of rotor winding b) has one-fourth the number of turns of each stator. The full-load speed is 1,455 rpm. The rotor resistance is 0.3 Ω and rotor standstill reactance is 1.0 Ω per phase. The rotor and stator windings are similar. Stator losses are equal to 50 Watts. Friction and windage losses are equal to 30 W. Calculate ) Blocked rotor voltage per phase. 2 Marks)...

  • A four-pole Y-connected, 415 V, 50 Hz, induction motor has phase equivalent circuit parameters of R1=...

    A four-pole Y-connected, 415 V, 50 Hz, induction motor has phase equivalent circuit parameters of R1= 2 ohms. R2=2.2 ohms. X1=X2=4 ohms. X(motor)=90 ohms Under rated condition, the rotor slip is 6%. (i) What is the rotor speed and rotor electrical frequency under the rated conditions; (ii) Calculate the stator input current, power factor, and electromagnetic torque under these conditions; (iii) The machine is running at rated conditions and it is to be stopped by switching the two stator leads....

ADVERTISEMENT
Free Homework Help App
Download From Google Play
Scan Your Homework
to Get Instant Free Answers
Need Online Homework Help?
Ask a Question
Get Answers For Free
Most questions answered within 3 hours.
ADVERTISEMENT
ADVERTISEMENT