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

1. 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

2. 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

3. 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

4. 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

5. 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

6. 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.

7. 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.

8. Motors

9. 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.

10. 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.

11. Heaters

12. 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.

13. 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.

14. Contactors and Relay

15. 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.

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

17. 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.

18. Switches

19. 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.

20. Safety Devices • Safety devices are important in today’s 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.

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

22. 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.