M/E Remote Control & CPP Pitch Control — Dredger

We renewed the main engine remote control and pitch control system of a dredger fitted with a controllable pitch propeller (CPP) using a Siemens S7-1200 PLC and SIMATIC KTP700 HMI. The existing no-name control system was not operating reliably, so the system was redesigned from scratch. A dual-lever (pitch and throttle) control head, a touch HMI and an emergency pitch control box added by us were installed on the bridge; a compact PLC enclosure in the engine room reads the engine and shaft speed from newly fitted speed sensors and drives the governor and pitch actuators.

Electric actuators are used for the governor (throttle) and pitch control; the PLC positions them according to the lever position. Clutch in/out, system on/off and mode selection are done on the HMI.

The system has three operating modes: in separate mode, pitch and speed are set independently with the two levers; in combinator mode, a single lever movement changes pitch and speed together along a predefined curve; in fixed-RPM mode the engine is held at constant speed and manoeuvring is done with pitch only. Engine rpm, shaft rpm, pitch percentage, clutch status and the active mode are shown live on the HMI.

The system was first run on a workshop test rig with the actual control head, actuators and HMI; it was then installed and commissioned on board and verified during sea trials.