AC transformers change incoming AC voltage to a lower AC output for devices such as surveillance equipment and access control hardware. DC power supplies convert input power to regulated DC, while power supply chargers also charge a standby battery and transfer connected equipment to that battery when primary AC power is lost.

Compare the power supply’s input voltage and output voltage, such as 115 VAC input with 12 VDC, 24 VDC, 16.5 VAC, or 24/28 VAC output, to the site power and connected equipment requirements. Check the total current or VA capacity, per-output limits, and any charging demand so the supply can support locks, cameras, readers, and accessories without exceeding its ratings.

Choose a power supply with multiple protected outputs when an access control or camera system powers several locks, readers, cameras, heaters, or other accessories from a shared source. Individually fused or PTC-protected outputs help distribute power by device and limit the effect of a short circuit or overload on the other connected equipment.

When connecting power supplies to batteries, use the supported sealed lead-acid or gel battery type, and account for the built-in charging and standby-power functions. Connections to fire alarm control panels should use the available fire alarm disconnect or FACP interface as required for the access system, while units that connect to building power should be wired by a certified electrician in accordance with applicable electrical requirements.