What is MCC on ship
The motor control centre consolidates all the motor controlling equipment for all the major motors on board the vessel.
Over-current and overload protection is provided to the motor and its immediate circuitry.
Motor Controls on Ship Power System
It is often convenient to group motor driven auxiliaries according to their function, e.g. fuel and lubrication oil services, accommodation ventilation systems, machinery ventilation systems and domestic service systems.
The auxiliary motors would be supplied from grouped motor controllers located either in the engine room, in a machinery control room or in a convenient location close to the auxiliary motors. This can often simplify the machinery control functions and required protection systems’ circuitry.
On small ships, e.g. tugs, etc., such grouping is not economical and the major ship’s auxiliaries are normally supplied directly from the main switchboard.
In this case the motors would be provided with individual starters located adjacent to the motor.
For high-speed vessels where weight is important, minimum cable weight may be achieved using a ‘non- distributed’ distribution scheme.
Auxiliary motor controls should be arranged in compliance with the general control philosophy applied to machinery control systems.
Not Automated Ship Power Panels
For ships that do not have automated machinery operation, the most economic method of control is to provide local starters for each auxiliary motor supplied from power panels located in the same or adjacent spaces.
These motors would be manually controlled (started and stopped), locally at the motor’s controller (e.g., a starter).
This arrangement minimises cable costs.
When a centralised machinery control system is required, cables for the motor control functions can be installed back to the machinery control room and the starter push buttons located on a centralised machinery control console.
Alternatively, the motors may be grouped together at motor control centres located inside the control room.
The motor control functions can then be left on the motor’s starter at the MCC or again wired back to a central control desk.
Fault on Fully automatic Ship Control System
When hard-wired systems are used, the installation is prone to mechanical problems, which may cause loose or broken connections; and the marine environment can also cause corroded connections.
These problems have been overcome to a certain extent by using microprocessors and digital control systems.
When fully automatic machinery control is required, these techniques are now m common use and microprocessor devices control the ship’s machinery through video display units (or desktop computers) located in the machinery control room or on the bridge.
The ship’s auxiliaries are generally controlled with programmable logic controllers (PLCs) installed inside the motor control centres and linked through a data bus to the machinery control location.
When this type of system is used, the motor control centres can be located either together in the machinery control room or alternatively, distributed throughout the ship close to the motors being controlled.
There is little difference in the cabling requirements of either method, however when motor control centres are located in a dry, atmosphere-controlled space such as the machinery control room, a higher degree of mechanical protection is required (IP 44 instead of IP 22) and consequently adds to the MCC costs (‘IP- stands for Ingress Protection ).
