Motor control centre MCC and distribution boards (DB) are constructed to a group together motor starters at convenient locations.
At the same time to centralize control of equipment or machinery whose operations are inter-related or inter-dependent.
General arrangements of the MMC/Distribution boards are: Isolator shall be provided at the main incoming side. The switch shall be interlocked with the door of its compartment to prevent the door from being opened when the isolator is switched “On”.
At starters compartment, only the push button, pilot lamp and instruments shall be exposed on the door panel. Circuit breaker, contractors and others shall be installed inside. The door shall be keyed or pad-lockable for safety during maintenance.
For large MCC such kernel station shall be provided with mimic diagram, indicating process flow.
Welding sockets 3 phases, 30 ampere shall be provided on the threshing/pressing station, kernel recovery station and boilers motor control centre.
Electric motor starters shall generally be as follows :
a. Induction motors up to 5 Hp shall Direct On Line (DOL) starting.
b. Above 5.5 Hp shall be star-delta configuration or auto-transformator multi step starter as necessary to a particularly load condition.
Interlocking of the starter shall be provided and the stopping or tripping of a
starter shall result in the tripping of the following in sequence:
1. Fibre/shell (fuel) conveyor.
2. Air lock-fibre cyclone.
3. Depericarter fan.
4. Nut polishing drum.
5. Cake breaker conveyor.
6. Screw press.
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