A water current power generation system comprising: a support structure for location on the bed of a body of water; a power generating unit adapted for mounting on the support structure, the power generating unit being adapted for rotation with respect to the support structure; a connection system arranged to provide at least one electrical connection between equipment of the support structure and equipment of the power generating unit; and a control system operable to monitor rotation of the power generating unit on the support structure, and to disengage said at least one electrical connection when rotation of the power generating unit on the support structure reaches a predetermined value, characterised in that the connection system comprises: a first connection point; a first support surface moveable linearly with respect to the first connection point; a second support surface moveable linearly and rotationally with respect to the first connection point; a second connection point moveable linearly and rotationally with respect to the first connection point, and moveable rotationally with respect to the first support surface, and fixed with respect to the second support surface; and a reverse bend radius cable chain located on the first and second support surfaces, and having a first end connected with the first connection point via a first connector cable, and a second end connected with the second connection point via a second connector cable, wherein the connection system is mounted on one of the support structure and power generating unit, the second support surface providing an electrical connection therefor, a second electrical connection being provided on the other of the support structure and power generating unit, and wherein the connection system has a first position in which the electrical connectors are engaged with one another, and a second position in which the electrical connectors are disengaged from one another, wherein the control system operable to monitor rotation of the second support surface of the connection system and to initiate movement of the connection system from the first position to the second position when rotation of the second support surface reaches a predetermined amount. a support structure for location on the bed of a body of water; a power generating unit adapted for mounting on the support structure, the power generating unit being adapted for rotation with respect to the support structure; a connection system arranged to provide at least one electrical connection between equipment of the support structure and equipment of the power generating unit; and a control system operable to monitor rotation of the power generating unit on the support structure, and to disengage said at least one electrical connection when rotation of the power generating unit on the support structure reaches a predetermined value, a first connection point; a first support surface moveable linearly with respect to the first connection point; a second support surface moveable linearly and rotationally with respect to the first connection point; a second connection point moveable linearly and rotationally with respect to the first connection point, and moveable rotationally with respect to the first support surface, and fixed with respect to the second support surface; and a reverse bend radius cable chain located on the first and second support surfaces, and having a first end connected with the first connection point via a first connector cable, and a second end connected with the second connection point via a second connector cable, wherein the connection system is mounted on one of the support structure and power generating unit, the second support surface providing an electrical connection therefor, a second electrical connection being provided on the other of the support structure and power generating unit, and wherein the connection system has a first position in which the electrical connectors are engaged with one another, and a second position in which the electrical connectors are disengaged from one another, wherein the control system operable to monitor rotation of the second support surface of the connection system and to initiate movement of the connection system from the first position to the second position when rotation of the second support surface reaches a predetermined amount.