ECET 211 Electric Machines & Controls Lecture 2-1 (Part 1 of 3) Symbols and Drawing for Electric Motor Control Systems

Transcription

1 ECET 211 Electric Machines & Controls Lecture 2-1 (Part 1 of 3) Symbols and Drawing for Electric Motor Control Systems Text Book: Chapter 2. Understanding Electrical Drawings, 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 Symbols and Drawings for Electric Motor Control Systems Chapter 2. Understanding Electrical Drawings Part 1. Symbols-Abbreviations-Ladder Diagram Motor Symbols Abbreviations for Motor Terms Motor Ladder Diagrams Part 2. Wiring Single Block Diagrams Part 3. Motor Terminal Connections Part 4. Motor Nameplates and Terminology Part 5. Manual and Magnetic Motor Starter Prof. Paul Lin 2 1

2 Symbols and Drawings for Electric Motor Control Systems Abbreviations and Symbols for Motor Terms Power Source PWR - Power AC Alternating Current 3PH three phase 1PH single phase DC Direct Current NEG - Negative POS - Positive REC - Rectifier TRANS - Transformer Prof. Paul Lin 3 Symbols and Drawings for Electric Motor Control Systems Single phase 120V 60Hz sinewave power source (max 15 A) MATLAB script for generating & plotting the waveform Vp = 120*sqrt(2); %Vp = 120* = volts f = 60; % 60 Hz, 60 sine waves per second T = 1/f; % Period T = 1/f = 1/60 = ms dt = T/100; % Take 100 samples per one period t = 0: dt: 2*T; % Plot for two cycles vt = Vp* sin(2*pi*f*t); plot(t, vt), grid on; xlabel(' time - second'); ylabel('volts'); Prof. Paul Lin 4 2

3 Symbols and Drawings for Electric Motor Control Systems Three phase 220V 60Hz sinewave power source MATLAB Program (script) Vp = 220*sqrt(2); %Vp = 220* = volts f = 60; % 60 Hz, 60 sine waves per second T = 1/f; % Period T = 1/f = 1/60 = ms dt = T/100; % Take 100 samples per one period theta1 = 0; theta2 = pi*(2/3); theta3 = pi*(4/3); t = 0: dt: 2*T; % Plot for two cycles v1 = Vp* sin(2*pi*f*t + theta1); v2 = Vp* sin(2*pi*f*t + theta2); v3 = Vp* sin(2*pi*f*t + theta3); plot(t, v1, t, v2, t, v3), grid on; xlabel(' time - second'), ylabel('volts'); Prof. Paul Lin 5 Symbols and Drawings for Electric Motor Control Systems 3PH 220V 60Hz sinewave power source Prof. Paul Lin 6 3

4 Abbreviations and Symbols for Motor Terms Abbreviations and Symbols for Motor Terms SW Switches BKR - Breaker Power On/Off Disconnect Switches Prof. Paul Lin 7 Understanding Electrical Drawings Abbreviations and Symbols for Motor Terms BRK - Breaker Prof. Paul Lin 8 4

5 Abbreviations and Symbols for Motor Terms Motor HP Horse Power MTR Motor PH - Phase 3PH three phase 1PH single phase L1, L2, L3 Power Line connections T1, T2, T3 Motor terminal connection Prof. Paul Lin 9 Abbreviations and Symbols for Motor Terms Transformer CT Current Transformer TRANS - Transformer (Control Transformer) PRI - Primary SEC - Secondary Prof. Paul Lin 10 5

6 Abbreviations and Symbols for Motor Terms DC Motor Related ARM Armature FLD - Field RH - Rheostat NEG -Negative POS - Positive Prof. Paul Lin 11 Abbreviations and Symbols for Motor Terms Relay, Magnetic Contactors, Switches CR - Control Relay M - Motor Starter NC - Normally Close NO - Normally Open COM - Common Prof. Paul Lin 12 6

7 Abbreviations and Symbols for Motor Terms Electromechanical Relay CR - Control Relay M - Motor Starter NC - Normally Close NO - Normally Open COM - Common Prof. Paul Lin 13 Abbreviations and Symbols for Motor Terms Actuators Switch Symbols Prof. Paul Lin 14 7

8 Abbreviations and Symbols for Motor Terms Human Machine Interface PB - Push Button PL - Pilot Light NC - Normally Close NO - Normally Open Prof. Paul Lin 15 Abbreviations and Symbols for Motor Terms Electrical Wires and Connections Circuit Protection Devices Prof. Paul Lin 16 8

9 Motor Control Diagrams and Drawings A variety of controls diagrams and drawings are used to install, maintain, and troubleshot motor control systems These diagrams include Ladder diagrams design and simulation Focuses on the electrical operation and sequence of a motor control circuit Block Diagrams Wiring diagrams Line Diagrams Prof. Paul Lin 17 Figure 2-3 A Typical Ladder Diagrams Two vertical rails (L1, L2) connected to power source Horizontal lines (rungs) contain control circuitry Read: Top => Down; Left to Right Prof. Paul Lin 18 9

10 Figure 2-4 Power and Control Circuit Wiring Control circuit Control Transformer ( v step down), Fuse, Temp SW, M coil, OL (Over load switch) Main power circuit 480v, three-m contacts, OL heating element, Motor Prof. Paul Lin 19 Figure 2-5 Identification of coils and associated contacts Control relay: R (coil), CR-1, CR-2 contacts Magnetic contactors (Starters): M1 (coil), M1 - - NO contact M2 (coil), M2 - \ - NC contact M3 (coil), M3 - \ - NC contact Prof. Paul Lin 20 10

11 Figure 2-6 Load and Control Devices Load a circuit components that has resistance and consumes electric power Parallel connection: all load elements receiving the same voltage Contacts LS control => Pilot Light (on/off) PB control => Solenoid (on/off), NC (contact) control => Heater element (on/off) Prof. Paul Lin 21 Figure 2-7 Load are placed on the right and contacts on the left Prof. Paul Lin 22 11

12 Figure 2-8 Stop devices connect in series and start devices connect in parallel Prof. Paul Lin 23 Figure 2-9 Differentiating between multiple devices of the same type Prof. Paul Lin 24 12

13 Figure 2-10 Ladder diagram with rung numbers detailed Prof. Paul Lin 25 Figure 2-12 Wiring numbering Prof. Paul Lin 26 13

14 Figure 2-13 Alternative wiring identification with documentation Prof. Paul Lin 27 Figure 2-14 Representing mechanical functions Mechanical Interlock Prof. Paul Lin 28 14

15 Figure 2-15 Control transformer grounding (a) control transformer properly grounded to the L2 side of the circuit. (b) control transformer improperly grounded at the L1 side of the circuit Prof. Paul Lin 29 Summary & Conclusion Study Chapter 2, Part 1 Review Questions, page 22 Prof. Paul Lin 30 15