The remote control system for the main engine is intended for use in the wheelhouse, the engine control room (ECR), and on the bridge wings for the purpose of controlling the engine by means of a combined telegraph and manoeuvring lever.
The Engine Manoeuvring System (EMS), which is interfaced to the Engine Control System (ECS), is what makes it possible to control the engine remotely from a distance (ECS). Every main engine has its own control system, complete with a telegraph lever of its own. When you move the active telegraph lever, the ECS will take over and automatically start, stop, and reverse the engine as well as control the speed setting.
The ECS is responsible for controlling the various functions of the engine’s operation based on the input signals that it receives from either the bridge or the local operation panels. The ECS is responsible for starting the engine in the correct direction and for controlling its operational functions, including the fuel injection and exhaust valve actuation, in order to ensure that the engine maintains the desired speed throughout its operation. The ECS is also responsible for providing safety features, which protect the engine in the event that any of the operational parameters exceed the limitations that have been set.
In most cases, the telegraph transmitter in the wheelhouse is used in conjunction with the engine management system (EMS) and the engine control system (ECS) to accomplish automatic maneuvering, which includes stopping, starting, and reversing the main engine.
The speed of the engine is automatically controlled, and the set point is transmitted from the telegraph transmitter located in the wheelhouse (or active station). The speed set point is communicated to the ECS, which, in turn, communicates with the ECUs to manage the engine speed.
For the purpose of determining the speed of the main engine, the Engine Control System (ECS) makes use of a Tacho Adapter Module to establish a connection between the tacho pick-ups that are attached to the engine and one of the CPUs that are located on the serial interface board.
The ECS works in conjunction with the independent main engine safety system (ESS) for main engine emergency stop, overspeed and shutdown protection.
In the engine control room the main engine safety system has its own panel, which displays the relevant information for each shutdown input channel, actual main engine rpm etc; it is also possible to make adjustments and cutouts on the shutdown input channels. Pushbuttons with LED indication on the ESS panel are used for Shutdown indication, Shutdown Cancel function and Shutdown Reset function. At the bridge, the shutdown and shutdown cancel functions are shown on two pushbuttons on the EMS panel.
The overspeed, shutdown and slowdown functions are carried out by the engine protection system in response to signals from sensors on the main engine and the ancillary systems. A wrong way alarm is also incorporated in the alarm system. Manual emergency stops are operated from pushbuttons on the bridge, bridge wings, engine control room console and LOP.
The bridge main operation station is equipped with a telegraph transmitter; the transmitter is equipped with a set point potentiometer and is located in the bridge centre console. The bridge telegraph transmitter is connected with the port and starboard bridge wing control panels. The ECR is equipped with a similar telegraph receiver. The bridge and ECR telegraph levers are equipped with potentiometers with hardware connections to the EMS system.
The electrical shaft system which interconnects the bridge telegraph with the bridge wing control telegraphs is a synchronising system, in which non-activated
control levers follow the active control lever. For example, when the bridge control is master, the two bridge wing levers automatically follow the master lever in the wheelhouse.
For back-up communication of telegraph orders from the bridge to the engine side local control stand, during local control, the system is fitted with a separate emergency telegraph system which is completely independent from the EMS. By means of a dial indicator and lamps for each telegraph order, the communication telegraph indicates the requested order. On the bridge the dial is moved to the position for the new order and the indicator lamp for that direction and speed will start flashing. At the engine side control station a bell will start sounding and the engine side emergency telegraph will start flashing for the desired speed and direction position.
To accept the new order the dial at the engine side control station telegraph must be turned to correspond with the desired engine speed and direction. The lamp will change to a steady light and the bell will stop.
Transfer to a control stand (target takes control) with higher priority is always possible without pre-selection (proposal/request) at an active control stand with lower priority. This transfer cannot be prevented at the control stand with lower priority. The local (engine side) control stand is the operating station with the highest priority. The engine control room has the next highest priority and the bridge control station the lowest priority.
A change from local control directly to automatic bridge control is not possible. There is only one exception: if an ECR telegraph potentiometer fault is present at the time of change request, the proposal to change to automatic bridge control is automatically given and has to be acknowledged.
When Bridge Control is selected and the system is not in FWE mode, starting, stopping and control of the main engine speed is controlled by the position of the bridge telegraph handle. Moving the telegraph handle from stop to ahead or astern will cause the starting sequence to be activated, ie, the ECS will be instructed to supply starting air until the main engine rpm has reached starting level. At this point starting air is removed and fuel is supplied and the engine speed is controlled as required.
If the main engine start attempt failed, a new repeated start will automatically be executed immediately. After three failed start attempts a start blocking occurs, and the bridge has to move the telegraph handle to the stop position before a new start can be performed.
If the main engine is ordered to move in the opposite direction whilst still rotating, starting air will not be supplied until the engine’s speed has decreased below the reversing level. The ECS controls braking air application to the engine and the engine can be brought to the reversing speed quickly as it is possible to regulate the braking air supply timing.
When ECR Control is selected the starting, stopping, reversing and speed control of the main engine is handled from the ECR telegraph handle located in the engine control room control console.
When the bridge requests a speed change the main engine direction and speed is altered by moving the bridge telegraph control handle to the desired position and this will initiate the telegraph alarm. An engineer in the ECR moves the ECR telegraph handle to the same position as that of the bridge telegraph. This performs the necessary speed and direction change and at the same time acknowledges the telegraph alarm.
If the engine is not ready for start, e.g, it is start blocked, the Start Block LED on the manoeuvring panel is illuminated. Starting interlock (blocking) is activated by the following:
- Main engine local control on
- Main engine safety system shutdown or emergency stop (control air pressure low, safety air pressure low, main start valve blocked, sain start valve blocked)
- Start failure (start air time-out or maximum number of failed start attempts)
- Turning gear engaged
- Start air pressure low
- Auxiliary blowers not in automatic
- Engine running
- Safety system off
- EMS malfunction
Slow turning of the main engine is normally used before the engine is started after a prolonged period of standstill and is done by turning the engine for 1-2 revolutions on reduced starting air. If the engine has been stopped for more than 30 minutes the system indicates that a slow turning should be initiated. The ECS activates the starting air system to supply starting air to the cylinders in reduced quantities so that the engine turns over slowly on a reduced starting air pressure. If the slow turning is not completed within the preset time the ECS signals a failure and blocks a further start until the cause of the failure has been rectified. If slow turning failure occurs the engine must not be started until the cause of the failure has been determined and corrected. In an emergency situation the start interlock can be cancelled by the CANCEL LIMITS at the bridge panel and the engine can be started.
A facility exists for prolonged turning over of the engine on air and this is known as Air Run. This facility is normally used after engine maintenance in order to check that the engine will turn readily or after prolonged stop in port.
The cylinder indicator cocks should be open when operating the air run facility. During air run the fuel command is automatically set to zero so there is no risk of the engine starting. The air run facility functions at engine standstill only and the engine turns on air whilst the AIR RUN pushbutton in the Manual Control panel is pressed.
If the start attempt is unsuccessful a second start attempt is initiated and REP. START is indicated in the display and a repeated start alarm is released. When the engine speed drops down below the firing speed the ECS will shut down the fuel supply to the engine fuel injectors and will initiate another start procedure.
If the engine stops again after the maximum number of start attempts (normally three), the start sequence is terminated with an alarm for three start attempts and a start blocking, which must be reset by putting the telegraph lever to the stop position before any further start attempts can be made.
The EMS hardware and peripherals are constantly monitored by the EMS in order to identify any faults which might develop. Supervision is usually carried out for:
- The bridge telegraph and ECR telegraph
- The speed sensing circuit
- The electronic governor
- The auxiliary voltages
- The solenoid valves
- The internal analogue/digital and digital/analogue converters
- The memory check
- The computer cycle
If a fault becomes active it is sensed by the EMS and this triggers audible and visual alarms; these are indicated at the operating panels on the bridge and in the ECR. The audible alarm is only activated at the station in control.
To comply with classification society rules, the system freezes the momentary operating conditions as far as possible. In a frozen condition the operator has to transfer control to manual mode in the ECR or at the engine local station. A reset can only be done in manual mode.
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