There are three types of overcurrent relay (OCR) used for motor protection: Electronic Thermal Electromagnetic Electronic OCIT (overcurrent inverse time) relays have largely supers... Read more
Protecting an electric motor basically involves preventing the motor from getting too hot. Remember, every 10*C above the maximum recommended temperature of the insulation can redu... Read more
The standard cage-rotor a.c. induction motor operates as an almost constant speed drive over its load range. This feature is satisfactory for most of the ship’s auxiliary ser... Read more
When motor direct-on-line started with the stator winding star connected, it will only take one-third of the starting current that it would take if the windings were delta connecte... Read more
LV generator circuit-breakers and other large distribution circuit-breakers (600-6000 A) on board ship are traditionally of the air break type called ACB (air circuit breaker). Thi... Read more
The central section of the main switchboard is used for the control of the main generators. The switchgear cubicles on either side of the generator panels are used for essential se... Read more
The power rating of an emergency generator is determined by the size and role of the ship. On some small vessels a few kW will suffice for emergency lighting only. Larger and more... Read more
The Chief Electronic Engineer is responsible for the management of the electronic department onboard to include all electronic equipment and communication/IT systems. The Ch... Read more
Sudden load current surges (e.g. due to motor starting) on a generator cause a corresponding change in its output voltage. This is due to an internal voltage drop in the generator... Read more
An undervoltage (U/V) release mechanism is fitted to all generator breakers and some main feeder circuit-breakers. Its main function is to trip the breaker when a severe voltage di... Read more
