Connection system arranged in a rack, for connecting at least one protection board (13a, 13b) of an electrical distribution system of an aircraft with a primary power supply, to at least one powered device (8a, 8b) and to a motherboard arranged in the rack.The connection system includes at least one modular connector on each protection board and, for each protection board capable of being inserted in the rack, at least one additional modular connector attached at least partly on the rack and at least one additional connector connected to the motherboard.