ECET 211 Electric Machines & Controls Lecture 8 Motor Control Circuits (2 of 2) Lecture 8 Motor Control Circuits

Transcription

1 ECET 211 Electric Machines & Controls Lecture 8 Motor Control Circuits (2 of 2) Text Book: Electric Motors and Control Systems, by Frank D. Petruzella, published by McGraw Hill, Paul I-Hai Lin, Professor of Electrical and Computer Engineering Technology P.E. States of Indiana & California Dept. of Computer, Electrical and Information Technology Purdue University Fort Wayne Campus Prof. Paul Lin 1 Lecture 8 Motor Control Circuits Part 1. NEC Motor Installation Part 3. Motor Reversing and Requirements Jogging Sixing Motor Branch Circuit Reversing of AC Induction Conductor Motors Branch Circuit Motor Reversing of DC Motors Protection Jogging Selecting a Motor Controller Part 4. Motor Stopping Disconnecting Means for Plugging and Anti-plugging Motor ad Controller Dynamic Breaking Providing a Control Circuit DC Injection Breaking Part 2. Motor Starting Electromechanical Friction Full-Voltage Starting of AC Brakes Induction Motors Part 5. Motor Speed Reduced-Voltage Starting Multispeed Motors of Induction Motors Wound-Rotor Motors DC Motor Starting Prof. Paul Lin 2 1

2 Lecture 8 Motor Control Circuits Part 3. Motor Reversing and Jogging Reversing of AC Induction Motors Reversing three-phase Induction Motor Starter Figure 8-29 Magnetic full-voltage three-phase reversing Prof. Paul Lin 3 Reversing of AC Induction Motors Figure 8-30 Mechanical interlocking of forward and reverse contactors Figure 8-31 Magnetic reversing starter with electrical interlock in the motor starter Prof. Paul Lin 4 2

3 Reversing of AC Induction Motors Figure 8-32 Reversing starter circuit implemented using IEC symbols Prof. Paul Lin 5 Reversing of AC Induction Motors Figure 8-33 Pushbutton interlocking Prof. Paul Lin 6 3

4 Reversing of AC Induction Motors Figure 8-34 Limit switches incorporated into a reversing starter circuit to limit travel Prof. Paul Lin 7 Reversing of AC Induction Motors Figure 8-35 Reversing a single-phase motor The direction of rotation is changed by interchanging the start winding leads, while those of the run winding remain the same Prof. Paul Lin 8 4

5 Reversing of AC Induction Motors Figure 8-36 Reciprocating machine process a repeated forward and reverse action Prof. Paul Lin 9 Reversing of DC Motors The reversal of a DC motor can be accomplished in two ways: Reversing the direction of the armature current (I A ); leaving the field current the same Reversing the direction of the field current (I F ) and leaving the armature current the same Figure 8-37 DC motor reversing power circuits Prof. Paul Lin 10 5

6 Jogging Jogging (sometimes called Inching) is momentary operation of a motor for the purpose of accomplishing small movements of the driven machine. Figure 8-38 Push button job circuit Prof. Paul Lin 11 Jogging Figure 8-39 Jog circuit with control relay Figure 8-40 Start/stop/selector jog control circuit Prof. Paul Lin 12 6

7 Motor Stopping Remove the power supply plus electric braking Plugging and Antiplugging Plugging stops a polyphase motor quickly by momentarily connecting the motor for revere rotation while the motor is still running in the forward direction. Figure 8-41 Plugging switch Part 4. Motor Stopping Figure 8-42 Plugging a motor to stop it Prof. Paul Lin 13 Plugging and Antiplugging Part 4. Motor Stopping Figure 8-43 Antiplugging protection circuit Prof. Paul Lin 14 7

8 Dynamic Braking Part 4. Motor Stopping Figure 8-44 Dynamic braking applied to a DC motor Prof. Paul Lin 15 DC Injection Braking Part 4. Motor Stopping Figure 8-45 DC injection braking applied to an DC Prof. Paul Lin 16 8

9 Part 4. Motor Stopping Electromechanical Friction Brake Figure 8-46 Electromechanical drum and shoe-type friction brake used on DC series motor drives Prof. Paul Lin 17 Part 4. Motor Stopping Electromechanical Friction Brake Figure 8-47 AC electromagnetic brake Prof. Paul Lin 18 9

10 Lecture 8 Motor Control Circuits Part 5. Motor Speed Multispeed Motors Figure 8-48 Two-speed separate winding across-the-line motor starter Prof. Paul Lin 19 Lecture 8 Motor Control Circuits Part 5. Motor Speed Wound-Rotor Motors Figure 8-49 Wound-rotor magnetic motor controller Low speed (full resistance) both S & H are open Medium speed S closed Maximum speed H closed Prof. Paul Lin 20 10

11 Summary & Conclusion Questions? Prof. Paul Lin 21 11