Signal isolation when EDC speed signal is used The MAN installation guide-lines stipulate that the engine must be potential-free. i.e. the battery must never be connected with the boat’s potential. This must also be borne in mind when the throttle lever control system is being con- nected up. The 4–20 mA throttle lever signal is galvanically separated from the EDC control box. The EDC speed signal is not. If the EDC speed signal is to be used for engine synchronisation and read into the throttle lever control system, take the following points into account:
a) potential-free further processing of the speed signal in the throttle lever control system + + Battery Engine 1 + MAN engine terminal box potential Boat’s EDC speed signal + + Battery Potential-free further processing for throttle lever control system Terminal box 2 (X) If a separate supply battery (2) is used to supply the throttle lever control system, a link (X) from its negative terminal to the boat’s potential is possible. If this is not guaranteed: b) The throttle lever control system should use the same negative potential as the MAN terminal box with integrated EDC control unit, i.e.
either the throttle lever control system should use the same battery for voltage supply as the starter motor, or the negative potentials of the supply batteries must be linked together. 101