This document discusses different types of switches used to control electrical circuits. It introduces single pole single throw (SPST) switches, which have a single input and output contact to open or close a circuit, and single pole double throw (SPDT) switches, which have one input but two output circuits where only one is energized at a time. Some specific switch types covered include toggle switches, slide switches, rocker switches, momentary switches, ganged switches, mercury switches, electromagnetic switches, position switches, and pressure switches.

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TECHVILL
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2.  Introduction to different types of switches.
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3.  To open and close a circuit
 Open (no connection)
 Closed (connection)
 Control device
 Does not consume power
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4.  Pole- what the switch armature is connected
to
Pole Throw
•• ThrowThrow- the closed position of- the closed position of
the switchthe switch
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5. Different types of switches:
 “SPST” – Single Pole / Single Throw
 “SPDT” – Single Pole / Double Throw
 Ganged Switch (MPMT)
 Mercury Switch
 Electromagnetic Switch
 Position Switch
 Pressure Switch
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6. ToggleToggle SlideSlide
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7. RockerRocker Push On/OffPush On/Off
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8. www.techvilla.org.in

9. SPST Switches
 Single pole input
 Single pole output
 A set of contacts inside the
switch opens or closes the circuit
 The contacts carry the current
load of the circuit when closed
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10. The “Momentary” Switch
 A SPST type switch
 Switch contacts are spring
loaded
 Closing the circuit requires
overcoming spring pressure
 Circuit is opened by spring
 Switch is (NO)www.techvilla.org.in

11. SPDT Switches
 One input circuit (pole)
 Two output circuits (throws)
 Only one output is energized at a time
 Contacts carry the current load of circuit
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12. Ganged Switches (MPMT)
 Contain multiple “wipers”
that operate in unison
 Contacts may carry
current load of circuit
 Contacts may supply
current to an
“electromagnetic switch”www.techvilla.org.in

13. Mercury Switches
 A SPST type switch
 Uses mercury as the
conductor for the contacts
 Accurate mounting of
mercury switches is essential
to proper operation
 Used on ground side of
circuit
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14. Electromagnetic Switches
 Also called a “relay”
 Uses a small amount of
current to control a
higher amperage circuit
 Relays are (NO) type
circuits
 Often controlled by low
amperage switch circuitwww.techvilla.org.in

15. Position Switches
 May be used on power or ground side of circuit
 Used to indicate whether a component is in the on
or off position
 Only provides a “high/low” signal to a solid state
control device
 A low current circuit
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16. Pressure Switches
 Can be used on either power or ground side of
circuit
 Switch is turned on/off by “pressure” rather than
a component’s movement
 Switch may carry current load of circuit
 Switch may be used as a type of position switch
for a solid state control device
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