This card in the Reserve Controller Director contains relays for PV and output switching during the failure of a primary controller. This card is used in the Basic, Extended, and Multifunction Reserve Controller Directors.

The RCD chassis must have one of the 30735863-001 cards, which can switch two primary controllers. To switch additional primary controllers, up to three of the optional 30735863-002 12-relay switch cards may be added to the RCD chassis, to switch a total of 8 primary controllers (2 controllers per switch card).

The 30735863-001 (the first switch card) has 16 relays. The additional test relays connect the reserve controller outputs to its inputs.

The toggle switch on this card is to enable/disable backup. The LED is illuminated when a backup is in progress.