In the event of a slow- or shut-down occurring, the appropriate lamps light up on the bridge telegraph and in the signal panel for emergency in the control room. If, with regard to the safety of the vessel, it proves necessary to start the engine again, the "cancel" button on the bridge telegraph can be activated. Since this is an emergency function, it will immediately release an alarm in the engine room.
If it is not imperative for the engine to run, the fault should be rectified before the engine is stated again. When the fault has been rectified, the reset button is pressed on the control room.
When this button is activated, the slow down circuit will be reset, and the engine will be automatically regulated up to the position of the handle. In the case of a shut-down, the engine will be automatically restarted after reset and the engine will regulate up to the value at which the bridge telegraph is set to.
Reset of a slow- or shut-down can also take place from the bridge by placing the telegraph on the bridge in stop position. An automatic reset order is thereby transmitted to the control panel, and if the slow- or shut-down condition has vanished automatic restart can be done by placing the telegraph in an arbitrary position.
However, it should be noted that it is only a reset arrangement. If the slow- or shut-down condition is still present, an automatic start can only be done by cancelling with the emergency buttons.
If an overspeed shut-down occurs, such a condition cannot be cancelled from the bridge by means of the cancelling button, but only by means of the regulating handle in the control room which has to be in the stop position.
When an overspeed shut-down has occurred, it should be noted that the fault could be due to a fault in the governor, or a fault in the remaining part of the manoeuvring system. In the case of an overspeed shut-down, the manual regulating system should be examined before the engine is allowed to start again and run to load.
A slow-down or shut-down can be due to a fault in the pressure switches or thermostates alone, without the measured value indicating a fault.
The contact for the appropriate channel can therefore be pressed in on the safety panel, thereby placing the channel out of action. This should, however, be carried out only whilst the pressure switch or thermostat is being replaced or repaired. A fixed light will appear in the safety panel whilst the channel is coupled out. It must be noted that such switching off a channel cannot cancel a slow- or shut-down. The reset button on the signal panel for emergency must always be pressed in afterwards.
When slowing down or shutting down the main engine on a vessel, several precautions must be taken to ensure safety and prevent damage to the engine and associated systems. Here are the key precautions:
Precautions During Slow-Down
Monitor Engine Parameters:
- Continuously monitor engine parameters such as temperature, pressure, and RPM.
- Ensure that all parameters are within safe limits during the slow-down process.
Gradual Reduction of Speed:
- Reduce the engine speed gradually to avoid thermal shock and mechanical stress.
- Follow the manufacturer's recommended procedures for deceleration.
Lubrication:
- Ensure that the lubrication system is functioning properly to avoid damage due to insufficient lubrication.
- Check oil pressure and temperature regularly.
Cooling System:
- Monitor the cooling system to ensure that the engine does not overheat.
- Adjust cooling water flow as needed to maintain proper temperature.
Fuel Management:
- Transition smoothly between different fuel types if required (e.g., switching from heavy fuel oil to diesel oil).
- Ensure proper atomization and combustion of fuel to prevent unburnt fuel accumulation.
Turbocharger Care:
- Be cautious with turbocharger speed and temperature.
- Ensure sufficient cooling and lubrication to avoid damage.
Precautions During Shut-Down
Step-by-Step Procedure:
- Follow a step-by-step shutdown procedure as per the engine manufacturer's guidelines.
- Do not shut down the engine abruptly to avoid thermal stress and mechanical damage.
Cooling Down:
- Allow the engine to cool down gradually to prevent thermal shock.
- Keep the cooling system running for a while after the engine is stopped to dissipate residual heat.
Lubrication:
- Maintain lubrication for a short period after shutdown to ensure that moving parts are adequately protected as they come to a stop.
Fuel System:
- Properly secure the fuel system by closing valves and draining fuel lines if necessary to prevent leakage and contamination.
Ventilation:
- Ensure proper ventilation to remove any residual exhaust gases and prevent the accumulation of flammable vapors.
Inspection:
- Conduct a thorough inspection of the engine and associated systems for any signs of wear, damage, or leaks.
- Address any issues identified during the inspection before the next start-up.
Securing the Engine:
- Lock out and tag out the engine controls to prevent accidental start-up.
- Ensure that all maintenance tasks are logged and communicated to the relevant personnel.
Documentation:
- Document the shutdown process, noting any abnormalities or issues encountered.
- Keep records for maintenance and operational review.
Safety Measures:
- Ensure all safety devices and alarms are operational.
- Have firefighting equipment and emergency procedures in place and ready for use if needed.
By adhering to these precautions, the main engine can be safely slowed down and shut down, minimizing the risk of damage and ensuring the longevity and reliability of the vessel's propulsion system.
