Automation helps the crew to operate the systems on board easier and safer. It will execute actions which are too complicated for the crew to handle in a given time. Automation allows automatic ob­servation of systems, registration of failures, registration of service time and planned maintenance. Detailed requirements for Auto­matic Control Systems on board of ships are described in IEC publication 60092-504 Control and instrumentation.

   1.  Automation

The level of automation depends on a number of factors:

Field I/O panel of a distributed automation and control system

1.1. More advanced systems

An operator workstation makes more sophisticated systems possi­ble, including control and display of engine room systems with sophis­ticated graphics. Trends over a period of time can be captured. Analyses of relationships between figures can be calculated. Running hours and the required automatic logging of all figures can be stored, along with many other statistics.

Some examples of systems that can be part of an automatic control system are:

-     Tank gauging system

From the simple, such as pro­viding liquid heights to the more sophisticated, giving tank contents in m³ or even in tons.

-     Reefer monitoring system

From failure alarms to com­plete data logs of the reefer's temperature and CO₂ content throughout the voyage, which can prove that cargo is not damaged due to transport.

-     Generator control and pow­er management system

From minimum automatic start­ing of a standby generator in case of generator failure and sequential restarting of all es­sentials to a complete load-de­pendent start-stop of the gen­erator plant. In this case, there is automatic power reduction in case of generator failure, until the standby generator is start­ed, has been synchronised, put on-line and has taken the load.

-     Propulsion remote control system

From straight forward remote control systems where each handle controls a single engine or propeller to state-of-the-art systems which can make a ship move 25 metres to port, rotate with the stern as rotating point over 90° to port, follow track or a link in location, adjust speed in accordance with available wa­ter depth.

In automation there are no techni­cal limits and therefore, a balance between expected results and cost has to be found.

Essential automation systems must be composed of type-approved equipment and are subject to an acceptance test at the manufac­turer's under conditions as real as possible.

Two automatic boilers

Governor controlling speed of auxiliary engine

Alternator junction box with AVR open cover

Automatic sewage plant

2  Local control systems

Some equipment has a dedicated local control system which is sepa­rated from the central automation system. Most of the time these local control systems exchange some param­eters with the central automation system. Examples are:

3  Essential services

Essential services are those servic­es required for sailing and keeping the ship in a habitable condition.

Electric power required for propul­sion can be supplied by a single generator set or by more sets in parallel. When supplied by a single generator, failure of this generator set should start a second generator. This generator should automatical­ly be connected to the switchboard followed by automatic restart of all essential auxiliaries.

A sequential start system may be required to limit the step load to the diesel engine.

Essential services include:

On ships sailing on heavy fuel oil, fuel oil circulating pumps, thermal oil circulating pumps and a thermal oil boiler are essential and must au­tomatically restart.

When the electric power required for propulsion is supplied by more generators in parallel, an automatic load shedding system must be fit­ted. This system reduces the load im­mediately to the capacity of the re­maining generator(s) after failure of one generator.

When large motors with frequency drives are installed the control sys­tem can be programmed to reduce the speed of the motors when the generators are close to be over­loaded. A complete shutdown of these mo­tors is then not required and when enough power is available again the motors can be set to the original speed.

Sequential restart timing priority:

When auxiliaries are engine driven and the engines can be started without lubricating oil pressure, this process is simpler.

 4  Failure mode and effect analysis

The Failure Mode and Effect Analy­sis is an appraisal of the result of a failure of equipment on the opera­tion of a ship (or any other type of equipment). This study is compulsory for units which have to fulfill the require­ments of the MODU Code.

The MODU Code is one of the IMO Codes, especially drawn up for off­shore equipment. MODU stands for Mobile Offshore Drilling Unit.

Originally for drilling equipment only, but later made a requirement for offshore equipment in general. FMEA is not limited to the automa­tion of electrical systems but covers all systems required for propulsion of a ship and all components.

The following example of an FMEA covers the layout, the auxiliary sys­tems and the electrical installation of a large pipe lay vessel with the following main characteristics:

The class notation DP(AA) or class 2, requires that a single failure does not result in loss of position of the vessel. Flooding or fire of a space is not considered in this notation.

The ship is designed for dual fuel but marine gas oil is used during DP operation with heavy fuel only for long passages or between jobs.

An FMEA addresses the items: