Part 6/10:
In HVAC systems, the common control voltage used in contactors is 24V AC. This low voltage is essential for safety, as it allows the power to be transmitted through thinner, more cost-effective wiring. The contactor itself serves as an interface between the low-voltage signal from the thermostat and the high-voltage supply necessary for the air conditioner to function.
Safety Mechanisms
Beyond simple power control, contactors also play a critical role in system safety. They ensure that if safety devices, such as pressure switches or overload relays, detect abnormal conditions, power can be interrupted without putting unnecessary strain on smaller switches that would typically face high current loads.