1 1 ECET 211 Electric Machines & Controls Lecture 4-1 Motor Control Devices: Part 1. Manually Operated Switch Part 2. Mechanically Operated Switch Text Book: 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 Lecture 4 Motor Control Devices Chapter 4. Motor Control Devices • Part 1. Manually Operated Switches • Part 2. Mechanically Operated Switches • Part 3. Sensors • Part 4. Actuators Prof. Paul Lin 2
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ECET 211 Electric Machines & Controls
Lecture 4-1 Motor Control Devices: Part 1. Manually Operated Switch
Part 2. Mechanically Operated Switch
Text Book: 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
Lecture 4 Motor Control Devices
Chapter 4. Motor Control Devices
• Part 1. Manually Operated Switches
• Part 2. Mechanically Operated Switches
• Part 3. Sensors
• Part 4. Actuators
Prof. Paul Lin 2
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Part 1. Manually Operated Switches
Primary and Pilot Control Devices
Toggle Switches
Push Button Switches
Pilot Lights
Selector Switch
Drum Switch
Prof. Paul Lin 3
Manually Operated Switches
Primary and Pilot Control Devices
Control device
• A component that governs the electric
power delivery to an electrical load
• Must be capable of handling the voltage
and current to be switched
Prof. Paul Lin 4
Two classes of control devices: Primary control and Pilot
control device
Primary control device:
• Motor contactor, Starter, or Controller that connect the load
to the line
• Contactor can also be used as pilot control device
Pilot control device:
• Relay, Switch contact that used to activate the primary
control device
• Should not be used to switch horsepower load
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Manually Operated Switches – Push Button SW
Figure 4-1 Primary and Pilot Control
Devices
• A typical motor control switch that
include both a Primary Control
(contactor), and a Pilot Control
device (toggle switch)
• Theory of operation
1. Turn toggle switch on to
complete the control circuit:
Power source (L1, L2) Toggle
switch Contactor’s coil M
2. Contactor energized => close
the M’s NO contacts => Deliver
power to the Motor
3. Turn toggle switch off =>
Contact M de-energized => the
M’s NO contacts open => Motor
stop Prof. Paul Lin 5
Manually Operated Switches – Toggle Switches
Types of toggle switch
• SPST – Single pole, single throw
• SPDT – Single pole, double throw
• DPST – Double pole, double throw
• DPDT – Double pole, double throw
Figure 4-2 Toggle switches
Electrical Rating for Switches
• Maximum interrupting voltage and current
• AC rating higher than DC rating for an equivalent amount of
voltage
• AC current is at zero level twice during each cycle
Prof. Paul Lin 6
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AC 120V 60Hz Since Wave
% sine120v.m
% MATLAB simulation
% 2014/1/13
% By Paul Lin
f = 60; %Frequency in Hz
T = 1/f; %Period in Second
dt = T/100; %Samlping time interval
Vrms = 120; % Root Mean Square voltage
t = 0: dt: 2*T; % Time vector
theta = 0; % Initial offset angle
e = 120*sqrt(2)*sin(2*pi*f*t + theta); % Voltage equation
% e = 120*1.414*sin(2*pi*f*t + theta); % Voltage equation