There are various types of diagram which attempt to show how an electrical Circuit operates on ship. Symbols are used to represent the various items of equipment.
The shipbuilder provides a complete set of ships’ electrical diagrams.
It is important that you study these diagrams to be able to read and understand them competently, and to use them as an aid in locating electrical faults.
How to read ship’s block diagram
A ship electrical block diagram shows in simplified form the main inter relationships of the elements in a system, and how the ship system works or may be operated. Such diagrams are often used to depict control systems and other complex relationships.
Picture describes the main functions of an overcurrent relay (OCR) used for protection. Its circuit diagram shows one way of realising the overall OCR function.
Diagrams like this state the function of each block but usually do not give any information about the components in each block or how the blocks are actually interconnected.
How to read ship’s system diagram
A ship system diagram shows the main features of a ship’s system and its bounds, without necessarily showing cause-to-effects main use is to illustrate the ways of operating the system. Detail is omitted in order to make the diagram as clear as possible, and so, easily understood.
How to read and understand ship’s circuit diagrams
A circuit diagram shows, in full, the functioning of a circuit.
All essential parts and connections are depicted by means of graphical symbols arranged to show the operation as clearly as possible but without regard to the physical layout of the various items, their parts or connections.
The electrical connections for a motor starter are clearly shown in the simplest possible way.
A most important point is that no attempt is made to show the moving contacts of a relay or contactor along side the coil that operates them (where they are actually physically located). Instead, the coil and its related contacts are identified by a common number or letter.
Although there are international agreements as to the symbol to be used to represent electrical components you must be prepared to meet various different symbols representing the same component.
The use of a ship circuit diagram is to enable the reader to understand the operation of the circuit, to follow each sequence in the operation from the moment of initiating the operation (e.g. by pressing a start button) to the final act (e.9. starting of the motor).
If the equipment fails to operate correctly, the reader can follow the sequence of operations until he comes to the operation that has failed.
The components involved in that faulty operation can then be examined to locate the suspect item.
There is no need to examine other components that are known to function correctly and have no influence on the fault, so the work is simplified.
A circuit diagram is an essential tool for fault finding on ship electrical system.