The most common power supply converts 120 VAC to what secondary voltage for controllers?

Study for the Direct Digital Controls and Lab Test with interactive questions and detailed explanations. Enhance your skills in managing digital systems and be fully prepared for success!

Multiple Choice

The most common power supply converts 120 VAC to what secondary voltage for controllers?

Explanation:
Power for controllers in Direct Digital Control comes from a step-down transformer that provides a safe, low-voltage supply. The standard control voltage in HVAC and building automation is 24 VAC. This voltage balances safety, ease of wiring (smaller conductors), and the ability to power the controller itself plus multiple field devices like relays, dampers, and valves. Since it’s AC, the supply can be run to the controller and then converted to DC internally if needed by the electronics. Other voltages are used in specific contexts, but 24 VAC is the most widely adopted because of compatibility, availability of transformers, and the ability to drive several devices from one supply.

Power for controllers in Direct Digital Control comes from a step-down transformer that provides a safe, low-voltage supply. The standard control voltage in HVAC and building automation is 24 VAC. This voltage balances safety, ease of wiring (smaller conductors), and the ability to power the controller itself plus multiple field devices like relays, dampers, and valves. Since it’s AC, the supply can be run to the controller and then converted to DC internally if needed by the electronics. Other voltages are used in specific contexts, but 24 VAC is the most widely adopted because of compatibility, availability of transformers, and the ability to drive several devices from one supply.

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