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ECET 211 Electric Machines & Controls
Lecture 2-2 (Part 2 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, 2015.
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
2. Symbols and Drawings for Electric Motor Control Systems
Chapter 2. Understanding Electrical Drawings
• Part 1. Symbols-Abbreviations-Ladder Diagram
• Part 2. Wiring – Single – Block Diagrams
• Part 3. Motor Terminal Connections
• Part 4. Motor Nameplates and Terminology
• Part 5. Manual and Magnetic Motor Starter
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Wiring Single-Line-Block Diagram
Wiring Diagrams – for wiring up systems
• To show the point-to-point wiring between components of an electrical system
• Include
ID Numbers and color coding assigned to conductors in the ladder diagrams
• Shows coils, contacts, motors in the actual locations
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Figure 2-16 Typical motor starter wiring diagram
Wiring Diagrams – for wiring up systems
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Figure 2-17 Routing of wires in cables and conduits
Conduit layout diagram: C1 - Conduit 1; C2 - Conduit 2
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Figure 2-18 Wiring with the internal connections of the magnetic starter omitted
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Figure 2-19 Combination wiring and ladder diagram,
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Figure 2-20 Single-line diagram of a motor installation
Single line (one-line) diagram uses symbols to show all major components of an electric circuit
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Figure 2-21 Single-line diagram of a power distribution system
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Figure 2-22 Block Diagram of a variable frequency AC drives
A block diagram represents the major functional parts of complex electrical/electronic system by blocks
• 3-phase 60Hz AC input
• The Rectifier block
• The Inverter block
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Motor Classification
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DC Motor Connections
DC Motor Applications: cranes, conveyors, elevators, material handling processes
Features
• Wide range speed control (down to almost zero), acceleration, reverse operation
• Can supply over 5-times rated torque without stalling
• Dynamic breaking (for quick stopping, reducing size of mechanical brake)
DC-motor generated energy is fed to a resistor grid, or
Regenerative braking (DC motor generated energy)
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DC Motor Connections
Figure 2-24 DC motor used on crane
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Figure 2-25 Parts of a DC compound motor
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Figure 2-26 Standard DC shunt motor connections for counter-clockwise and clockwise rotation
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Figure 2-27 Standard DC series motor connections for counter-clockwise and clockwise rotation
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Figure 2-28 Standard DC compount motor connections for counter-clockwise and clockwise
rotation
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AC Motor Connections
Single-phase motor connections
Three-phase motor connections
Dual-voltage motor connections
Multispeed motor connections
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Figure 2-29 Three-phase squirrel-cage AC induction motor
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Baldor Motor Manufacturing Plants
ABB Robotics – Electric Motor Manufacturing at Baldor, 3 to 15 HP, (ABB), Nov. 18, 2013 , 6 min, https://www.youtube.com/watch?v=V21_lqOhOZc
Baldor – Fort Smith, Arkansas Motor Plant, 6: 67 min, https://www.youtube.com/watch?v=rrEYh7H7VhA
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Figure 2-30 AC split-phase induction motor
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Figure 2-31 Dual-voltage split-phase motor stator connection
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Figure 2-32 Permanent-split capacitor motor
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Figure 2-33 Three-phase wye and delta motor connection
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Figure 2-34 Dual voltage three-phase wye connection
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Multi-Speed Motor
Motor Speed:
• Stator Field Speed = 120 x Frequency/Number of Poles, N = 120 * f/P
• Rotor shaft speed: Nr = N* (1 – slip); slip ranged from 0.03 to 0.05
Speed change methods
• N = 120*f/P => change the number of poles 2, 4, 6, 8
• N = 120*f/P => change the frequency from the power source
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Figure 2-35 Constant horse-power two-speed, three phase motor and controller
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Figure 2-36 Reversing the direction of rotation of a three phase motor
Interchange of any two power leads
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Figure 2-36 Reversing phase relay circuit Monitor the correct phase rotation sequence
A solid-state sensing circuit => • Relay energized => NO contact closed (if correct phase
sequence)
• Relay energized => NO contact closed (if correct phase sequence)
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Summary & Conclusion
Questions?
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