Components, Symbols, and Circuitry of Air-Conditioning Wiring Diagrams

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Components, Symbols, and Circuitry of
Air-Conditioning Wiring Diagrams

• Electricity for Refrigeration, Heating and Air
  Conditioning 7th Edition

Chapter 5 Components, Symbols, and Circuitry of
Air-Conditioning Wiring Diagrams
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Components, Symbols, and Circuitry of
Air-Conditioning Wiring Diagrams

• Upon completion of this chapter the student will
  be able to

• Explain what electrical loads are and their
  general purpose in heating, cooling, and
  refrigeration systems
• Give examples of common loads used in heating,
  cooling, and refrigeration systems
• Identify the symbols of common loads used in
  heating, cooling, and refrigeration systems
• Explain the purpose of relays and contactors in
  heating, cooling, and refrigeration systems
• Identify the symbols of relays and contactors in
  heating, cooling, and refrigeration systems

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Components, Symbols, and Circuitry of
Air-Conditioning Wiring Diagrams

• Upon completion of this chapter the student will
  be able to

• Explain the purpose of switches and the types
  used in heating, cooling, and refrigeration
  systems
• Identify the symbols of switches in heating,
  cooling, and refrigeration systems
• Identify the symbols and purpose of other
  miscellaneous controls in heating, cooling, and
  refrigeration systems
• Identify the different types of wiring diagrams
  used in the industry and the purpose of each
• Read simple schematic diagrams
• Read advanced schematic diagrams

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Key Terms

• Contractor
• De-energized
• Disconnect Switch
• Energized
• Factual Diagram
• Fuse
• Heater
• Installation Diagram
• Load
• Magnetic Overload
• Magnetic Starter
• Motor
• Normally
• Normally Closed
• Normally Open

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Key Terms

• Pictorial Diagram
• Pilot Duty Device
• Pole
• Pressure Switch
• Push-button Switch
• Relay
• Schematic Diagram
• Signal Light
• Solenoid
• Switch
• Thermal Overload
• Thermostat
• Throw
• Transformer

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Loads

• Loads are electrical devices that consume
  electricity to do useful work.
• Load are devices such as motors, solenoids,
  resistance heaters and other current-consuming
  devices.
• Load are the most important part of a heating,
  cooling, or refrigeration system because they do
  all the work in the system.

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Motors

• A motor is an electrical device that consumes
  electric energy to rotate a device in an electric
  system.
• Motors are used in the industry to rotate devices
  such as compressors, condenser fan motors, pump,
  and other units that require rotating movement.

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Motors
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Solenoids

• The solenoid is a device that creates a magnetic
  field when energized and causes some action to an
  electric component such as a relay or valve.
• A solenoid is considered to be a load because it
  consumes electricity to do useful work.

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Heaters

• Heaters are loads that are found in many systems
  and wiring diagrams.
• A heater takes electrical energy and converts it
  to heat.
• In some cases, electric resistance heaters are
  used to heat homes.

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Heaters
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Signal Lights

• A signal light is a light that illuminated to
  denote a certain condition in a system.
• The letter inside the signal light symbol denotes
  the color of the signal light.
• A signal light is used to show that a piece of
  equipment is operating or that it is operating in
  an unsafe condition.

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Contactors and Relay

• Contractors and relays are devices that open and
  close a set or sets of electric contacts by
  action of solenoid coil.
• The contactor or relay is composed of a solenoid
  and the contacts.
• When the solenoid is energized, the contacts will
  open or close, depending on their original
  position.

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Contactors and Relay
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Terms

• Normally refers to the position of a set of
  contacts when the device is de-energized.
• Normally open is a set of contact that are
  normally open, however, when the relay is
  energized the contacts are closed.
• Normally closed is a set of contact that are
  normally close, however, when the relay is
  energized the contacts are open.

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Magnetic Starters

• A magnetic starter is the same type of device as
  a contactor in terms of the ampere rating of the
  device.

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Switches

• A switch is a device that opens and closes to
  control some load in an electric circuit.
• Electric switches can be opened and closed by
  temperature, pressure, humidity, flow or by some
  manual means.
• The throw indicates how the switch may be
  operated.

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Switches
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Terms

• The disconnect switch is used to open and close
  the main power source to a piece of equipment or
  load.
• The push-button switch is a symbol used to open
  and close a set of contacts by pressing a button.
• Thermostats are mechanically operated switches
  used in most control systems.
• Pressure switches are used for different
  functions in modern control circuits.

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Safety Devices

• Safety devices are important in todays modern
  systems.
• The fuse is the simplest type of overload
  devices.
• The fuse is effective against a large overload,
  but it is less effective against small overloads.
• The thermal overload is operated by heat.
• The magnetic overload is operated by magnetism,
  which is directly proportional to the current
  draw.

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Transformers

• The transformer decreases or increases the
  incoming voltage to a desired voltage.

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Schematic Diagrams

• Most modern heating, cooling and refrigeration
  systems are becoming more complex with more
  controls and safety devices.
• The schematic diagram is the most useful and
  easiest to follow of any electric diagram.
• The schematic diagram tells how, when and why a
  system works.
• The schematic wiring diagram includes the symbols
  and the line representations so the user can
  easily identify loads and switches along with the
  circuits.