Basic Electric 3 HVAC Electric Components WWW.HVAC-WTC.COM

4.2.1 Switches Single-pole, single-throw (SPST) Double-pole, single-throw (DPST) Double-pole, double-throw (DPDT) INSTRUCTOR NOTES: Explain that these pole and throw arrangements also apply to relays. Basic Electricity 03106-13

Common Switch Applications 4.2.1 Common Switch Applications Switches are used in many ways, even to respond to light or moisture. INSTRUCTOR NOTES: Talk about the different ways thermostatic and pressure switches are used to control system functions. Basic Electricity 03106-13

4.2.2 Circuit Breaker Panel Special HACR circuit breakers are used for air conditioning equipment for the same reason that slow-blow fuses are used. INSTRUCTOR NOTES: Explain the difference between magnetic- and thermal-trip circuit breakers. Basic Electricity 03106-13

4.2.3 Solenoid The operating coil of a solenoid valve essentially creates an electromagnet when it is energized. Basic Electricity 03106-13

4.2.4 Control Relays Contactors and motor starters are simply relays that control greater amounts of current and/or have additional features related to motor protection. Basic Electricity 03106-13

4.2.5 Control Transformer INSTRUCTOR NOTES: Discuss the different transformer forms and common applications. Explain how control transformers are rated. Basic Electricity 03106-13

4.2.8 Electronic Controls Printed circuit boards contain items such as miniature relays, terminals for wiring connections, resistors, diodes, and capacitors. INSTRUCTOR NOTES: Discuss the applications of electronic controls. Explain that most boards are not field-repaired, but that technicians must determine if a failure was related to the board itself or to an external problem. Basic Electricity 03106-13