A marine electrician is someone who installs and takes care of electrical equipment and systems on board ships and boats. He or she may also handle emergency repairs on ships in port, in dry dock, and out at sea. Simple electrical systems fall under the responsibilities of a marine electrician, while more advanced technology may require a marine engineer.
An overview of a ship’s electrical system is presented and describes various types of circuit diagram used in electrical work. Electrical calculatons, safety precautions, circuit diagrams and testing methods are outlined together with a description of general electrical maintenance and fault techniques. The electrical power system on board ship is designed to provide a secure supply to all loads with adequate build-in protecton for the equipment and operating personal. The general scheme of a ship’s electrical power system is common to nearly all ship.
The main a.c.generators (sometimes called alternators) produce the electrical power. It is supplied to the main switchboard an then distributed to have various auxiliary services comprising the electrical load. An emergency generator and emergency switchboard maintain supplies in the event of a main power failure.
Shipboard power is generated using a prime mover and an alternator working together. For this an alternating current generator is used on board. The generator works on the principle that when a magnetic field around a conductor varies, a current is induced in the conductor.
The generator consists of a stationary set of conductors wound in coils on an iron core. This is known as the stator. A rotating magnet called the rotor turns inside this stator producing magnetic field. This field cuts across the conductor, generating an induced EMF or electro-magnetic force as the mechanical input causes the rotor to turn.
The magnetic field is generated by induction (in a brushless alternator) and by a rotor winding energized by DC current through slip rings and brushes. Few points to be noted about power on board are :
3 phases is preferred over single phase as it draws more power and in the event of failure of one phase, other 2 can still work.
The Power Distributed on board a ship needs to be supplied efficiently throughout the ship. For this the power distribution system of the ship is used.
A shipboard distribution system consists of different component for distribution and safe operation of the system. They are :
In case of the failure of the main power generation system on the ship, an emergency power system or a standby system is also present. The emergency power supply ensures that the essential machinery and system continues to operate the ship.
Emergency power can be supplied by batteries or an emergency generator or even both systems can be used.
Rating of the emergency power supply should be made in such a way that it provides supply to the essential systems of the ship such as :
b) Emergency bilge and fire pump.
c) Watertight doors.
e) Ships navigation lights and emergency lights.
f) Communication and alarm system.
Emergency generator is normally located outside the machinery space of the ship. This is done mainly to avoid those emergency situations wherein access to the engine room is not possible. A switch board in the emergency generator room supplies power to different essential machinery.
This website uses cookies.