Three-Phase Induction Motor Starters

Transcription

1 Electricity and New Energy Three-Phase Induction Motor Starters Courseware Sample F0

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3 Safety and Common Symbols Caution, risk of danger Festo Didactic III

4 Safety and Common Symbols IV Festo Didactic

5 Table of Contents Festo Didactic V

6 Table of Contents VI Festo Didactic

7 Preface Festo Didactic VII

8 Preface VIII Festo Didactic

9 About This Manual Manual objectives Safety considerations Prerequisite DC Power Circuits Single-Phase AC Power Circuits Three-Phase AC Power Circuits Three-Phase Rotating Machines Systems of units Festo Didactic IX

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11 To the Instructor Accuracy of measurements Equipment installation Festo Didactic XI

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13 Sample Exercise Extracted from the Student Manual and the Instructor Guide

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15 Exercise 1 DOL Starters and Soft Starters EXERCISE OBJECTIVE DISCUSSION OUTLINE Overcurrent protection. Overload protection. Start up current. Consequences of extended large currents. Voltage sag. Start-up torque. Voltage output of a soft starter. Effect of the soft starter on the motor current. Effect of the soft starter on the motor torque. Effect of the soft starter on the motor speed. How a soft starter controls voltage. Bypass circuit. Types of soft starters. DISCUSSION Introduction Direct-on-line starters Festo Didactic

16 Exercise 1 DOL Starters and Soft Starters Discussion Motor protections Overcurrent protection 8 Festo Didactic

17 Exercise 1 DOL Starters and Soft Starters Discussion D )XVHV E &LUFXLW EUHDNHUV )LJXUH 2YHUFXUUHQW SURWHFWLRQ GHYLFHV Overload protection $W VWDUW XS D PRWRU UHTXLUHV D FXUUHQW KLJKHU WKDQ WKH QRPLQDO FXUUHQW XQWLO WKH URWDWLRQ VSHHG VWDELOL]HV 7KH PRWRU RYHUFXUUHQW SURWHFWLRQ LV VHOHFWHG VR WKDW LWV UDWHG FXUUHQW LV DERYH WKH PRWRU VWDUW XS FXUUHQW &RQVHTXHQWO\ D FXUUHQW ORZHU WKDQ WKH RYHUFXUUHQW SURWHFWLRQ UDWHG FXUUHQW EXW KLJKHU WKDQ WKH PRWRU QRPLQDO FXUUHQW FDQ IORZ LQ WKH PRWRU ZLQGLQJV $ FXUUHQW RI VXFK YDOXH FDQ FDXVH RYHUKHDWLQJ DQG HYHQWXDOO\ GDPDJH WKH PRWRU LI LW FLUFXODWHV LQ WKH ZLQGLQJV IRU DQ H[WHQGHG SHULRG KHQFH WKH QHHG IRU RYHUORDG SURWHFWLRQ LQ DGGLWLRQ WR RYHUFXUUHQW SURWHFWLRQ 2YHUORDG SURWHFWLRQ FRPPRQO\ LPSOHPHQWHG ZLWK DQ RYHUORDG UHOD\ SURWHFWV D FLUFXLW IURP RYHUKHDWLQJ GXH WR D KLJK FXUUHQW WKDW IORZV IRU WRR ORQJ 0RWRU VWDUWHUV VRPHWLPHV FRPH ZLWK D EXLOW LQ RYHUORDG UHOD\ RWKHUZLVH WKH RYHUORDG SURWHFWLRQ PXVW EH LQVWDOOHG VHSDUDWHO\ 2YHUORDG UHOD\V DUH PDLQO\ GHILQHG E\ WKHLU WULSSLQJ FODVV %\ GHILQLWLRQ WKH WULSSLQJ FODVV LV WKH QXPEHU RI VHFRQGV LW WDNHV IRU WKH RYHUORDG UHOD\ WR WULS LI WKH FXUUHQW LV VL[ WLPHV LWV FXUUHQW VHWWLQJ )RU H[DPSOH D FODVV RYHUORDG UHOD\ ZLWK D $ FXUUHQW VHWWLQJ WULSV DIWHU VHFRQGV LI D $ FXUUHQW JRHV WKURXJK LW &ODVV RYHUORDG UHOD\V DUH XVXDOO\ XVHG ZLWK PRWRUV WKDW KHDW UDSLGO\ VXFK DV KHUPHWLF PRWRUV +LJKHU FODVV RYHUORDG UHOD\V DUH PRVWO\ XVHG ZLWK PRWRUV GULYLQJ KLJK LQHUWLD ORDGV WKDW WDNH WLPH WR DFFHOHUDWH 7KH DERYH GHILQLWLRQ LV QRW VXIILFLHQW WR GHILQH WKH EHKDYLRU RI DQ RYHUORDG UHOD\ LQ HYHU\ VLWXDWLRQ $Q DGGLWLRQDO UHTXLUHPHQW IRU DQ RYHUORDG UHOD\ LV WKDW LW VKRXOG QHYHU WULS LI WKH FXUUHQW LV HTXDO RU EHORZ LWV FXUUHQW VHWWLQJ,Q EHWZHHQ WKH FXUUHQW VHWWLQJ DQG VL[ WLPHV WKH FXUUHQW VHWWLQJ WKH UHODWLRQVKLS EHWZHHQ WKH FXUUHQW DQG WULSSLQJ WLPH YDULHV VOLJKWO\ GHSHQGLQJ RQ WKH RYHUORDG GHVLJQ Festo Didactic

18 Exercise 1 DOL Starters and Soft Starters Discussion 10 Festo Didactic

19 Exercise 1 DOL Starters and Soft Starters Discussion Motor start-up phenomena Start up current Festo Didactic

20 Exercise 1 DOL Starters and Soft Starters Discussion Consequences of extended large currents 12 Festo Didactic

21 Exercise 1 DOL Starters and Soft Starters Discussion Voltage sag Start-up torque Festo Didactic

22 Exercise 1 DOL Starters and Soft Starters Discussion Soft starters 14 Festo Didactic

23 Exercise 1 DOL Starters and Soft Starters Discussion Voltage output of a soft starter Festo Didactic

24 Exercise 1 DOL Starters and Soft Starters Discussion Effect of the soft starter on the motor current 16 Festo Didactic

25 Exercise 1 DOL Starters and Soft Starters Discussion Poly.(DOL) Poly.(SS) Effect of the soft starter on the motor torque Festo Didactic

26 Exercise 1 DOL Starters and Soft Starters Discussion Effect of the soft starter on the motor speed 18 Festo Didactic

27 Exercise 1 DOL Starters and Soft Starters Discussion Poly.(SpeedDOL (rev/min)) Poly.(SS) How a soft starter controls voltage Festo Didactic

28 Exercise 1 DOL Starters and Soft Starters Discussion 20 Festo Didactic

29 Exercise 1 DOL Starters and Soft Starters Discussion Bypass circuit Types of soft starters Festo Didactic

30 Exercise 1 DOL Starters and Soft Starters Discussion 22 Festo Didactic

31 Exercise 1 DOL Starters and Soft Starters Procedure Outline PROCEDURE OUTLINE PROCEDURE Setup and connections In this part of the exercise, you will connect your equipment as a DOL starter, configure parameters in LVDAC-EMS so that the Four-Quadrant Dynamometer/Power Supply emulates a flywheel, and set the Oscilloscope to observe the motor start-up current, torque, and speed. Power Input Power Input Low Power Input Power Input Festo Didactic

32 Exercise 1 DOL Starters and Soft Starters Procedure Operating ModeDynamometer Computer-Based InstrumentationThyristor Control OK Tools Friction Compensation Calibration OK OK OI I1 a Current input I4 of the Data Acquisition and Control Interface is used to monitor the motor current in order to protect the motor from overheating if excessive currents flow through the stator windings. The range of current to be used for current input I4 is 40 A. 24 Festo Didactic

33 Exercise 1 DOL Starters and Soft Starters Procedure I1 I1 Sync. Festo Didactic

34 Exercise 1 DOL Starters and Soft Starters Procedure Digital Output 1DO1D + Remote Control Analog OutputsT n Analog Inputs/T /n Analog Outputs A Function Mechanical Load Load Type Flywheel Inertia Friction Torque Pulley Ratio a Note that the pulley ratio between the Four-Quadrant Power Supply/Dynamometer and the Four-Pole Squirrel Cage Induction Motor is 24:24. FunctionDirect On-Line Starter Motor Full Load Current [FLA] OverloadOn Overload Class 26 Festo Didactic

35 Exercise 1 DOL Starters and Soft Starters Procedure I1) Analog Input 7/T Analog Input 8/n Peak Detect Starting an induction motor using a DOL starter In this part of the exercise, you will start the motor using a DOL starter. You will record the motor current, torque, and speed at start-up and analyze the results. StatusStarted Start/Stop Single Refresh Start a The above manipulation must be performed rapidly to ensure that the Oscilloscope records the entire evolution of the various parameters during motor start-up. Stop a Since the Oscilloscope operates in peak detect mode and a slow time base is used, it displays the envelope of the motor current rather than its waveform. Status Stopped Start/Stop Festo Didactic

36 Exercise 1 DOL Starters and Soft Starters Procedure 28 Festo Didactic

37 Exercise 1 DOL Starters and Soft Starters Procedure a The maximal current obtained in step 22 is a peak value. Convert this peak value to an rms value before making the comparison. Festo Didactic

38 Exercise 1 DOL Starters and Soft Starters Procedure 30 Festo Didactic

39 Exercise 1 DOL Starters and Soft Starters Procedure Soft starter setup and settings In this section, you will modify the equipment connections so as to replace the DOL starter with a soft starter. I1 Festo Didactic

40 Exercise 1 DOL Starters and Soft Starters Procedure I1 32 Festo Didactic

41 Exercise 1 DOL Starters and Soft Starters Procedure Sync. Digital Output 1 Remote Control T and n Analog Outputs Analog Inputs7/T8/n Digital Outputs Firing Control Inputs Range I1 FunctionSoft Starter ModeSoft Start Motor Full Load Current [FLA] Initial Torque Start Time Soft Starter Initial Torque Kick Start Time Soft Stop OverloadOn Overload Class Festo Didactic

42 Exercise 1 DOL Starters and Soft Starters Procedure Starting an induction motor using a soft starter In this part of the exercise, you will start the motor, still coupled to the same mechanical load used earlier in the exercise, using a soft starter. You will record the motor current, torque, and speed at start-up and analyze the results. Single Refresh Start a The above manipulation must be performed rapidly to ensure the Oscilloscope records the entire evolution of the various parameters during motor start-up. Stop 34 Festo Didactic

43 Exercise 1 DOL Starters and Soft Starters Procedure Festo Didactic

44 Exercise 1 DOL Starters and Soft Starters Procedure 36 Festo Didactic

45 Exercise 1 DOL Starters and Soft Starters Procedure DOL starter versus soft starter In this part of the exercise, you will compare the results you obtained with the DOL starter and the soft starter (for the same mechanical load) and try to deduce what the advantages and limitations of each one are. Festo Didactic

46 Exercise 1 DOL Starters and Soft Starters Conclusion Tools Reset to Default Friction Compensation Yes CONCLUSION REVIEW QUESTIONS 38 Festo Didactic

47 Exercise 1 DOL Starters and Soft Starters Review Questions Festo Didactic

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49 Bibliography Foundations of Analog and Digital Electronic Circuits Industrial Power Engineering and Applications Handbook Practical Variable Speed Drives and Power Electronics The Induction Machine Handbook Power Electronics Handbook Electrical Machines, Drives and Power Systems Power Conversion and Control of Wind Energy Systems Festo Didactic