MOTOR CONTROL CENTER [MCC]
MCC stands for Motor Control Center. It consists of feeders for motors and blowers. Feeders are designed according to the motor rating. In most of the MCC is, auto/manual provision will be there.
With manual provision, motors can be operated manually. In auto-provision external signal is required to start the motor. The signal is given by the control panel. Indicators for the motor operation also will be present in the control panel.
A Motor Control Center [MCC] is an assembly of one or more enclosed sections having a common power bus and principally containing motor control units. Motor Control Center [MCC] is in modern practice a factory assembly of several motor starters.
A Motor Control Center [MCC] can include variable frequency drives, programmable controllers, and metering and may also be the electrical service entrance for the building. A motor control center (MCC) is an assembly to control some or all-electric motors in a central location.
It consists of multiple enclosed sections having a common power bus and with each section containing a combination starter, which in turn consists of a motor starter, fuses or circuit breaker, and power disconnect.
A motor control center can also include pushbuttons, indicator lights, variable-frequency drives, programmable logic controllers, and metering equipment. It may be combined with the electrical service entrance for the building. For both classifications of MCC, each motor controller contains a contactor or a solid-state motor controller, overload relays to protect the motor, fuses or a circuit breaker to provide short-circuit protection, and a disconnecting switch to isolate the motor circuit.
Three-phase power enters each controller through separable connectors. The motor is wired to terminals in the controller. MCCs provide wire ways for field control and power cables. Each motor controller in an MCC can be specified with a range of options such as separate control transformers, pilot lamps, control switches, extra control terminal blocks, various types of bi-metal and solid-state overload protection relays, or various classes of power fuses or types of circuit breakers. An MCC can either be supplied ready for the customer to connect all field wiring or can be an engineered assembly with internal control and interlocking wiring to a central control terminal panel board or programmable controller. An MCC is generally mounted on floors, which are often required to have a fire-resistance rating. Fire stops may be required for cables that penetrate fire-rated floors and walls.
An Intelligent MCC uses a smart, electronic protection device in lieu of a conventional thermal overload device, to accommodate various protection functions, depending on configuration and software. However, each control unit uses devices that have embedded intelligence. Specifically, PLC, Soft Starters, circuit breakers, contactors, and AC Drives can provide information over an internal network which can further support communication networks to higher level systems in the operation. Most common network supported outside of the cabinet includes Profibus, ProfiNet, CCLink, Ethernet\IP, DeviceNet or Modbus). This communication link is often connected directly to the PLC mounted inside the cabinet. The PLC performs protection, communication, control, and monitoring functions.
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