A Motor Control Centre (MCC) is an assembly of one or more enclosed sections having a common power bus and principally containing motor control units. Motor control centres are in modern practice a factory assembly of several motor starters. A motor control centre can include variable frequency drives, programmable controllers, and metering and may also be the electrical service entrance for the building. Motor Control Centres nave been used by the automobile manufacturing industry which used large numbers of electric motors. Today, they are used in many industrial and commercial applications. Where very dusty or corrosive processes are used, the motor control centre may be installed in a separate air conditioned room. But often an MCC will be on the factory floor adjacent to the machinery controlled.