2.1 Explain controls systems used for propulsion machine and auxiliary machines.
2.1 Description of Electrical Controls on the Main Engine and Auxiliary Engines
Main Engine Control System for Internal Combustion Marine Diesel Engines
Main engine control system is used for automatic remote control and protection of main ship's diesels. It permits to change direction and speed rotation of propeller directly from the bridge by navigators. The system consists of the equipment installed on the bridge, engine control room (ECR) locally mounted near the engine.
The set of Engine Remote Control equipment in ECR essentially consists of a panel fitted up with the various signaling, alarm and control facilities, in addition to the electronic modules (both logic and analog).
Electronic Control Modules Rack comprises:
1. Engine starting and reversal logic module, with LED display (direction of rotation indicator) of logic status and starting set-point adjust potentiometer status;
2. Digital/analog engine RPM converter with cut-in thresholds and LED display of the status of the thresholds and thresholds adjusting potentiometers.
3. Engine control programmer with LED display of stand-by, RPM reduction, emergency, etc. and acceleration gradient adjusting potentiometer.
4. RPM controller with potentiometers for variables and operating limits adjustment.
5. Torque limiter, with limit indicator.
Locally Mounted Equipment comprises electro-hydraulic type actuator, for remote control of the fuel linkages; the said actuator is continuously linked mechanically to the lever and is therefore driven by the manual hand wheel when it is de-energized.
The equipment also comprises induction type pick-ups to monitor the number of RPM's and rotating direction, as well as a five-position servo-motor, complete with four devices to position the engine local control lever for reversing gears and starting air distributors for engine stop, running ahead, starting ahead, running astern, starting astern.
Equipment on Bridge comprises:
1. Engine telegraph.
2. Automatic control panel. It has the following items mounted on panel front:
a). Manual power limiter.
b). Engine speed fine adjustment potentiometer.
c). Illuminated push-button for bridge control demand.
d). "Control transfer inhibited" signal display.
e). "Control on the bridge/ECR" signal display.
f). Direction of engine rotation indicator (LED).
g). Engine RPM indicator.
i). Fuel oil lever actuator position indicator.
3. Shield push-button for emergency stop and emergency maneuvering.
Bridge control of Main Engines:
Automatic control of the starting of the main engine can be done from the bridge as well as in Engine control room. The automatic controls employed in starting the engine are by the following sequence:
i). Automatic control used in correctly positioning of the cam shaft.
ii). Admitting starting air
iii). Admitting fuel
iv). Starting air shut off
v). Speed adjustment to the value required
Thus the engine is started and the various parameters like temperature, pressure, flow and tank level have to measure at every watch to make sure that the engine is running safely.
i). Temperatures of lube oil, JCW, exhaust gas, etc. is measured.
ii). Pressures of lube oil, JCW, fuel oil, and starting air etc. are measured.
iii). Flow of fuel oil is measured while running.
iv). Tank levels of Heavy fuel oil, diesel oil, and lube oil are measured.
For measuring the parameters we make use of the transducers, in turn sending the input signal to the automatic control system.
DIESEL GENERATOR
i). This is employed in automatic starting and stopping of the auxiliary generator from the engine control room. So of the automatic control used are:
ii). Starting and stopping of the engine according to the load demand.
iii). Synchronization of incoming generator.
iv). Closing the circuit breaker
v). Load sharing between the alternators
vi). Maintaining the supply frequency and voltage.
vii). Engine and alternator fault protection
viii). Preferential tripping of non-essential loads.
