ecet 211 electric machines & controls lecture 2-1 (part 1...

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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, 2015.

Paul I-Hai Lin

Professor of Electrical and Computer Engineering TechnologyP.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• 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

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Abbreviations and Symbols for Motor TermsPower Source

• PWR - Power

• AC – Alternating Current

• 3PH – three phase• 1PH – single phase• DC – Direct Current

• NEG - Negative• POS - Positive• REC - Rectifier• TRANS - Transformer

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1PH 120V 60Hz sinewave power source (max 15 A)

MATLAB script for generating & plotting the waveformVp = 120*sqrt(2); %Vp = 120* 1.414 = 169.68 volts

f = 60; % 60 Hz, 60 sine waves per second

T = 1/f; % Period T = 1/f = 1/60 = 16.67 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');

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3PH 220V 60Hz sinewave power source

MATLAB Program (script)Vp = 220*sqrt(2); %Vp = 220* 1.414 = 311.08 volts

f = 60; % 60 Hz, 60 sine waves per second

T = 1/f; % Period T = 1/f = 1/60 = 16.67 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);



plot(t, v1, t, v2, t, v3), grid on;

xlabel(' time - second'), ylabel('volts');

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3PH 220V 60Hz sinewave power source

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0 0.005 0.01 0.015 0.02 0.025 0.03 0.035-400

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Abbreviations and Symbols for Motor Terms


Abbreviations and Symbols for Motor TermsSW – Switches BKR - Breaker

Power On/Off Disconnect

Switches

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Abbreviations and Symbols for Motor TermsBRK - Breaker

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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

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Transformer

• CT – Current Transformer

• TRANS - Transformer (Control Transformer)

• PRI - Primary

• SEC - Secondary

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DC Motor Related

• ARM – Armature

• FLD - Field

• RH - Rheostat

• NEG - Negative• POS - Positive

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Relay, Magnetic Contactors, Switches

• CR - Control Relay

• M - Motor Starter

• NC - Normally Close

• NO - Normally Open

• COM - Common

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Electromechanical Relay

• CR - Control Relay

• M - Motor Starter



• COM - Common

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Actuators

Switch Symbols

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Human Machine Interface

• PB - Push Button

• PL - Pilot Light



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Electrical Wires and Connections

Circuit Protection Devices

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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

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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

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Figure 2-4 Power and Control Circuit Wiring

Control circuit – Control Transformer (480-120 v step down), Fuse, Temp SW, M coil, OL (Over load switch)

Main power circuit – 480v, three-M contacts, OL heating element, Motor

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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

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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) ontrol => Heater element (on/off)

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Figure 2-7 Load are placed on the right and contacts on the left

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Figure 2-8 Stop devices connect in series and start devices connect in parallel

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Figure 2-9 Differentiating between multiple devices of the same type

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Figure 2-10 Ladder diagram with rung numbers detailed

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Figure 2-12 Wiring numbering

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Figure 2-13 Alternative wiring identification with documentation

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Figure 2-14 Representing mechanical functions

Mechanical Interlock

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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

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Summary & Conclusion

Email: [email protected] or [email protected]

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ecet 211 electric machines & controls lecture 2-1 (part 1...

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