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1.5: Circuit Control Devices

  • Page ID
    3290
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    • Contributed by Camosun College
    • Sourced from BCCampus (Download for free at http://open.bccampus.ca/find-open-textbooks)

    Controlling a circuit is an essential part of the electrical system. The control devices will turn circuits on and off as well as limit the conditions within the circuit, including amperage and voltage.

    Circuit control devices include:

    • resistors
    • switches
    • relays
    • solenoids

    Resistors

    Resistors are used in circuits where full current flow may not be required. One side effect of resistors is that they produce heat. There are three common resistors found in most circuits:

    • fixed
    • stepped
    • variable

    Fixed resistors

    Fixed resistors (Figure \(\PageIndex{1}\)) restrict current flow or voltage and are connected into the circuit or built right into a component. In some cases, this resistance is provided by wires. These are special wires that can be identified by markings that state “resistor wire—do not cut or splice.”

    4.png
    Figure \(\PageIndex{1}\): Fixed resistors (CC BY-NC-SA; BC Industry Training Authority)
    tappedResistors.png
    Figure \(\PageIndex{2}\): Stepped resistor (CC BY-NC-SA; BC Industry Training Authority)
    5.png
    Figure \(\PageIndex{3}\): Variable resistors (CC BY-NC-SA; BC Industry Training Authority)
    6.png
    Figure \(\PageIndex{4}\): Slide, rocker, and toggle switches (CC BY-NC-SA; BC Industry Training Authority)
    DPDT.png
    Figure \(\PageIndex{5}\): Double pole double throw switch (CC BY-NC-SA; BC Industry Training Authority)
    rotarySwitch.jpg
    Figure \(\PageIndex{6}\): Rotary switch (CC BY-NC-SA; BC Industry Training Authority)
    momentaryContactSwitch.jpg
    Figure \(\PageIndex{7}\): Momentary contact switch (CC BY-NC-SA; BC Industry Training Authority)
    temperatureSensitiveSwitch.png
    Figure \(\PageIndex{8}\): Temperature-sensitive switch (CC BY-NC-SA; BC Industry Training Authority)
    relays.png
    Figure \(\PageIndex{9}\): Relay (CC BY-NC-SA; BC Industry Training Authority)
    solenoid.png
    Figure \(\PageIndex{10}\): Solenoid (CC BY-NC-SA; BC Industry Training Authority)