Buildings motor control center

The engineer providing the initial design of major facilities is faced with the decision of providing a motor control center building or indi id-ual (usually rack-mounted) motor starters and corresponding branch circuit protection devices. For installations using only several motors it fre-... 

For facilities that include large numbers of motors and other electrical equipment, it normally is both more economical and more convenient to furnish a building to enclose the required motor starters and distribution panels. This building is normally referred to as a motor control center (MCC). In addition to typically allowing less expensive non-explosion-proof equipment, these buildings are frequently environmentally controlled (air conditioned, and possibly heated in colder climates) to reduce equipment corrosion and enhance reliability. Maintenance is more easily performed indoors than if the equipment were installed outside and maintenance personnel were subject to extreme cold, rain, snow, or other adverse weather conditions. 

The motor control center (MCC) and Substation have concrete block load bearing walls of ordinary construction. The control house is of blast resistant construction with reinforced concrete walls and roof designed for 0.2 bar static. All three buildings are 4 m tall. 

Building 5—A motor control center (MCC) constructed of unreinforced masonry. An electrician spends 1 hour a day monitoring equipment in the MCC. The MCC provides power for process equipment critical to the continued operation of the facility. Critical power for safety shutdown equipment for both Process Units 1 and 2 is located in Building 5. 

This table shows the home office hours required by a large contractor to design and procure the different types of equipment normally encountered in a chemical plant. The hours comprise all technical and clerical activities from the start of process design to project closeout. They are intended for a continuous operation, single unit plant with electronic DCS instrumentation built on a direct-hire basis on a clear site and include process-related buildings, such as a motor control center and control room. 

Electrical switchgear, circuit breakers, switches, and small transformers are normally grouped together in a building or Motor Control Center (MCC). Climate controlled buildings may also be required to house minicomputers, transducer banks, and other instrument interfaces. Putting this equipment in a building protects it from fires and explosions in the process area. 

The loss of two motor control centers (at the time of the hydrogen burn) meant that the ac oil lift pumps were out of service. It is not possible to start a reactor coolant pump unless the oil lift pump can be started. There is a standby dc oil lift pump, but it was necessary to send people to the auxiliary building to start it. 

The possibility that motor control centers and other equipment within the basement of the reactor building could possibly flood and short-out, thereby causing a mini-blackout that incapacitates ECS before it is initiated by operator action has not yet been addressed and is considered an open item. 

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