Marine Electrics & Electronics

A big advantage of A.C. transmission is the ability to easily change voltage by means of a transformer. As there are no moving parts maintenance is very low and efficiency very high ( typically 98%).

The wire coil of the electromagnet, without its core of magnetic material is called the solenoid. If this solenoid is provided with a movable soft iron core and current flows through the turns of the coil , the magnetic field tends to pull the plunger in to the centre of the coil. Accordingly the coil with its moving centre is called the solenoid.

Discharge lamps
Cold cathode type-only used for decorative lighting
Hot cathode

• a, High pressure fluorescent

(i)Mercury vapour types) Used mainly for street lighting
(ii) Sodium type , ) but sometimes used for deck lighting

• b, Low pressure Hot Cathode Fluorescent type discharge Lamp
  Read more

  Add comment (0)

  Hits: 271

When the double pole switch is closed the navigation light is illuminated. Current in the relay circuit causes the relay coil to energise so contact 'a' ,may be attracted to 'b'.

If voltages exceed 250 volts d.c. or 55 volts A.C. then the switchboard must be dead front (no exposed live parts at the front) of the metal clad type.

The effect of a large load suddenly switched on to a small power installation such as a ships plant will be an instantaneous dip in the generator voltage.