Part 3 Description - 4100 Series

The relay expansion board(s) provides independent relay control for the charging circuits of the system. During an off-peak period, the system determines the number of elements required to achieve the targeted heat level. The relays located on the relay expansion board(s) for the required elements are then closed, energizing the elements. Every 15 minutes, the system evaluates the number of elements required and randomly changes which elements are energized. This prolongs the life of the elements and ensures that the brick core is evenly heated.

Line voltage power to the relay expansion board(s) comes in on the L1 and L2 240 terminals and through a 1/4A (250mA) fuse. An interface cable connects the base I/O relay board to the first relay expansion board. At the base I/O board, this interface cable must be connected to the port labeled "expansion". In systems with two relay expansion boards, the first relay expansion board is then connected to the second relay expansion board with an interface cable.