What voltage is the power supply for the remote unit

Most remote units, including RTUs, typically use a 24 VDC power supply, with some systems supporting 12 VDC or AC-to-DC conversion.

Standard Voltage for Remote Units

Remote Terminal Units (RTUs) and similar remote units generally operate on DC power, most commonly 24 volts DC. This voltage ensures stable operation of the RTU and compatibility with connected field instruments and sensors . In cases where only AC mains power is available, a DC power supply unit converts AC voltage to the required 24 VDC output to maintain proper operation . Some remote units, such as fire alarm auxiliary power supplies, may also support 12 VDC for specific applications .

Power Supply Features

• Battery Backup: Many remote units include rechargeable batteries (lead-acid, lithium-ion, or nickel-cadmium) to maintain continuous operation during AC power outages, providing a steady 24 VDC output .
• Solar Integration: In remote or off-grid locations, solar panels can charge the battery system, ensuring uninterrupted 24 VDC power .
• Regulated Output: Remote power supplies often provide regulated and filtered DC output to protect sensitive electronics and field devices .
• Auxiliary Applications: Some units, like the 27-032 remote power supply, can provide multiple outputs for notification circuits or auxiliary devices, all at 24 VDC .

Summary

For most industrial and remote automation applications, the remote unit power supply is 24 VDC, with optional support for 12 VDC in certain systems. AC mains can be converted to DC if necessary, and battery or solar backup ensures continuous operation in remote or hazardous locations . This voltage standard is widely used to power RTUs, sensors, actuators, and auxiliary devices reliably.