1 / 23

Determination of Induction-Motor Parameters

Determination of Induction-Motor Parameters. DC Test Determines R 1 Connect any two stator leads to a variable-voltage DC power supply Adjust the power supply to provide rated stator current Determine the resistance from the voltmeter and ammeter readings. For a Y-Connected Stator.

leecampbell
Download Presentation

Determination of Induction-Motor Parameters

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Determination of Induction-Motor Parameters • DC Test • Determines R1 • Connect any two stator leads to a variable-voltage DC power supply • Adjust the power supply to provide rated stator current • Determine the resistance from the voltmeter and ammeter readings ECE 441

  2. ECE 441

  3. For a Y-Connected Stator ECE 441

  4. For a Delta-Connected Stator ECE 441

  5. Determination of Induction-Motor Parameters • Blocked-Rotor Test • Determine X1 and X2 • Determines R2 when combined with data from the DC Test • Block the rotor so that it will not turn • Connect to a variable-voltage AC supply and adjust until the blocked-rotor current is equal to the rated current ECE 441

  6. ECE 441

  7. Simplified Equivalent Circuit Neglect the exciting current under blocked-rotor conditions – remove the parallel branch ECE 441

  8. IEEE test code recommends that the blocked-rotor test be made using 25% rated frequency with the test voltage adjusted to obtain approximately rated current. A 60-Hz motor would use a 15-Hz test voltage. The calculated reactance is corrected to 60-Hz by multiplying by 60/15. Calculated resistance is correct. ECE 441

  9. ECE 441

  10. ECE 441

  11. How Is the Blocked-Rotor Impedance Divided? If the NEMA-design letter of the motor is known, use Table 5.10 to divide the impedances. Otherwise, divide the impedances equally. ECE 441

  12. Determination of Induction-Motor Parameters • No-Load Test • Determine the magnetizing reactance, XM and combined core, friction, and windage losses. • Connect as for blocked-rotor test (next slide). • The rotor is unblocked and allowed to run unloaded at rated voltage and rated frequency. ECE 441

  13. Electrical connection for the No-Load Test is the same as for the Blocked-Rotor Test ECE 441

  14. Determination of Induction-Motor Parameters • At no-load, the speed is very close to synchronous speed – the slip is =0, causing the current in R2/s to be very small, and will be ignored i the calculations. • IM>>Ife, so I0 = IM. ECE 441

  15. The equivalent circuit for the no-load test is shown. Ignore ECE 441

  16. Substitute X1 from the blocked-rotor test to determine the value of XM. ECE 441

  17. Example 5.16 • The following data were obtained from no-load, blocked-rotor, and DC tests of a three-phase, wye-connected, 40-hp, 60-Hz, 460-V, design B induction motor whose rated current is 57.8A. The blocked-rotor test was made at 15 Hz. ECE 441

  18. Blocked-Rotor No-Load DC Vline = 36.2V Vline = 460.0V VDC = 12.0V Iline = 58.0A Iline = 32.7A IDC = 59.0A P3phase = 2573.4W P3phase = 4664.4W a) Determine R1, X1, R2, X2, XM, and the combined core, friction, and windage loss. b) Express the no-load current as a percent of rated current. ECE 441

  19. Convert the AC test data to corresponding phase values for a wye-connected motor. ECE 441

  20. Determine R1 Determine R2 ECE 441

  21. Determination of X1 and X2 From Table 5.10, for a design B machine, X1 = 0.4XBR,60 = 0.4(1.0182) = 0.4073Ω/phase X2 = 0.6XBR,60 = 0.6(1.0182) = 0.6109/phase ECE 441

  22. Determination of XM ECE 441

  23. Determination of combined friction, windage, and core loss: b) Express the no-load current as a percent of rated current. ECE 441

More Related