The legacy Bulk AC to 24 VDC and Bulk AC to 12 VDC power supplies are available as both DIN rail and panel-mounted units. Both types of power supplies can be used in redundant systems and the legacy DIN rail-mounted supply can be used in systems requiring load sharing as well as redundancy. The legacy DIN rail-mounted supply contains an integrated OR-ing diode to isolate power supply faults. Refer to “OR-ing Diodes” for usage information. The legacy panel-mounted power supply cannot be used in systems that require load sharing.
If you have redundant system power supplies, connect the redundant legacy Bulk AC to 12 VDC power supplies to different System Power Supplies (Dual DC/DC) on each controller and I/O subsystem.
The legacy DIN rail-mounted Bulk AC to 24 VDC power supply provides 24 VDC power to field devices and System Power Supplies (Dual DC/DC). This power supply provides enough power for approximately 40 AI, AO, and dry contact DI cards.