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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?Contact Prof. Lin through:

Email: pilin@purdue.edu, or lin@ipfw.edu

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