A power supply with either 1 x 8A 12V DC (13.7V) or 1 x 4A 24V DC (27.4V) output. The output voltage is changed by means of a simple selector plug. This unit can also house and charge one or two VRLA batteries up to 7Ah capacity and can signal a mains failure with relay contacts.
This unit also has a completely independent SPCO relay that can be driven from a 12V or 24V DC supply regardless of PCB selector position (e.g. if PCB is in 24V mode, this relay can still be used in 12V mode or not at all). A typical use for this relay would be for interfacing with a fire panel to de-power items such as magnetic locks in the event of an emergency.