Solid State Electronics : Circuit Symbols and Diagrams for HVAC

 

1. Importance of Electrical Symbols:

   • Serve as the universal language of electricity in circuit diagrams.
   • Represent electrical components using standard symbols.
   • Understanding symbols is essential for reading diagrams and understanding circuitry.

2. Placement and Meaning:

   • The placement of symbols and interconnecting lines shows the electrical circuits within equipment.
   • Understanding the location of components in relation to others helps trace the current's path through the circuit.

3. Types of Symbols:

   • Loads: Consume electrical energy (e.g., motors, lights).
   • Switches: Control the circuit (e.g., toggle, push button).
   • Controls: Switches that respond to specific conditions (e.g., thermostats, humidistats, pressure switches).
   • Power Supplies: Indicated by solid or dashed lines, with line thickness showing different voltages or wiring types.

4. Types of Diagrams:

   • Schematic (Ladder) Diagrams: Show the circuit's function and logic, resembling a ladder.
     • Line voltage is depicted as rails; circuit sections as rungs.
     • Useful for troubleshooting control systems, indicating sequence of operations.
   • Pictorial Diagrams: Show actual locations of components and their interconnecting wiring.
     • Used as blueprints to locate components and wires.
     • Differ from schematics by showing the physical layout and appearance of components.

5. Reading Diagrams:

   • Schematic diagrams help visualize how power is applied and controlled within the circuit.
   • Pictorial diagrams assist in locating specific components or wires based on the schematic's information.

6. Using Diagrams in HVAC:

   • Look for wiring diagrams attached to the unit or in manuals.
   • Manufacturers provide both pictorial and schematic diagrams, along with legends for abbreviations and symbols.
   • Diagrams are essential for installing and troubleshooting equipment.

7. Understanding Ladder Diagrams:

   • Show logic without indicating actual wiring shapes.
   • Depict sequence of operations with components like compressors, fan motors, relays, switches, and capacitors.
   • Power source typically at the top, with loads arranged by voltage draw.

8. Additional Information in Schematics:

   • May include connections to thermostats and other controls, increasing complexity.
   • Line thickness and dashes may indicate voltage levels and factory versus field wiring.