In electrical engineering and construction, “MCC” stands for “Motor Control Center.” When an industrial application uses more than one electrical motor, it’s desirable to control one or more of them from one location. The purpose is to make the operation process easy and effective.
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MCC meaning in electrical?
In electrical engineering and construction, “MCC” stands for “Motor Control Center.” An MCC is an integrated assembly of motor starters, variable frequency drives, control circuitry, and other components used to control and manage electric motors in industrial and commercial applications.
MCCs provide a centralized location for motor control, protection, and monitoring, making it easier to manage multiple motors in a facility.
They are commonly used in manufacturing plants, refineries, commercial buildings, and various industrial settings to control motors responsible for tasks such as pumps, conveyors, fans, and other machinery.
Why is It Important to Have (MCC)?
MCC is a great time, cost, and effort saver for maintenance and operator teams, below are some of MCC’s advantages:
- It centralizes all or some motor control and operation in one place.
- Makes it easier to perform preventive maintenance for motor control panels and components.
- Cost-effectiveness. MCC needs one power source. We usually use one main bus bar to feed all of them.
- MCCs need less wiring effort and cost. All MMCs have all or most of the motors of the organization in one place.
- MCCs provide a higher fault detection system. As they are all in the same location, it is easy for one operator to regularly check all of them and detect any possible faults early.
Controlling each motor from individual places rather than MCC makes it hard to make regular routine preventive maintenance.
As I mentioned above, the organization that I work for has an MCC. This MCC makes it super easy for us as a maintenance team to do the preventive maintenance tasks.
We simply go to the control building get current and voltage measurements, and check all contactors and control devices. All this is in the same location. A great time saving, isn’t it?
I can imagine the great effort of doing such maintenance tasks if the motor control of each one is in a separate location.
This motor control center also makes it easy for operating staff to start, stop, or isolate any of these motors.
MCC panel Components
A Motor Control Center (MCC) panel is a standardized assembly that contains various components for the control and protection of electric motors.
These components are organized within the MCC panel to facilitate the operation, monitoring, and maintenance of electric motors.
Here are the key components typically found in an MCC panel:
Motor Starters: Motor starters are devices that provide the means to start and stop electric motors. They can include various types of starters such as:
- Full-Voltage Starters: These provide a direct supply of power to the motor.
- Reduced-Voltage Starters: These gradually apply voltage to the motor to reduce inrush current and mechanical stress during startup. Types include star-delta starters and autotransformer starters.
- Variable Frequency Drives (VFDs): VFDs are used for controlling the speed and torque of motors by varying the frequency and voltage supplied to them.
Overload Protection: Overload protection devices, such as overload relays or thermal overload heaters, are used to protect motors from excessive current and overheating. They can trip the motor starter in case of overloads or faults.
Control Devices: MCC panels include various control devices and components, including:
- Push Buttons and Pilot Lights: These are used for manual control, status indication, and fault indication.
- Selector Switches: These enable operators to select different motor operating modes, such as forward or reverse.
- Control Transformers: Control transformers step down voltage to power control circuits and devices safely.
Control Circuitry: MCC panels include control circuits that facilitate the operation of control devices, interlocking, and sequence control for motors.
Protection Devices: Protection devices ensure the safety of the motor and MCC. Common protection devices include:
- Circuit Breakers: These provide short-circuit and overcurrent protection for the entire MCC panel.
- Fuses: Fuses protect against overcurrent and short circuits in individual circuits.
- Ground Fault Protection: Ground fault protection devices detect ground faults and provide protection against electric shock hazards.
Busbars: Busbars are conductive bars that distribute electrical power from the incoming supply to the various motor starters within the MCC panel.
Interlocking Mechanisms: Interlocking systems prevent the simultaneous operation of conflicting motor starters, helping to avoid accidents and equipment damage.
Instrumentation: Depending on the complexity of the MCC panel, it may include instrumentation such as ammeters, voltmeters, and power meters to monitor electrical parameters and motor performance.
Communication and Networking: In modern MCCs, there may be communication interfaces or networking components to connect the MCC panel to a supervisory control system for remote monitoring and control.
Enclosure: The MCC panel is enclosed in a cabinet or enclosure to protect the components from environmental factors, dust, and physical damage.
The specific components and their arrangement within an MCC panel can vary depending on the application, the number of motors being controlled, and the design standards and requirements of the facility.
In the design and selection phase of MCC, design engineers specify the components of the panel.
Each MCC has its own requirements according to the application the motor is working on.
Some common components are in almost all applications. These are :
- Motor starter.
- Overload relay
- Circuit breaker and fusible switch.
- Start and stop buttons.
- Indicator lamps for each phase.
In one MCC, you may find each motor controller has its own control and protection devices as the design requires.
This panel in the image has many control devices, these devices control more than one load. It has the following control components:
- Circuit breakers.
- Solid State relays (SSR).
- Control relays.
- PLC controllers.
How to set motor control center specifications to purchase?
When you are responsible for setting specifications of an MCC, you should make it clear and complete to be easy for the purchasing team.
The main data of any MCC should include the following:
- Operating voltage.
- Phases number.
- The current of each load.
- Protection levels for each load.
- Maximum suggested dimensions. To be suitable for your control room.
- The IP rating of the enclosures.
- Power cable sizes, to make sure that the panel has suitable openings for cables entrance.
- Short circuit ratings.
Make sure to check the following data with the motor control center supplier:
- As built drawing.
- Testing certificates.
- All data sheets for all components.
- The manufacturer of the MCC should be the Manufacturer of the major components.
- Installation information.
- The manufacturer of the components should be in the industry for at least 5 years.
- The motor control center should have spare control panels for the most important loads.
- If the organization has an inventory, make sure that the components of the MCC are the same in the inventory.
- Spare parts list.
An “MCC room” refers to a Motor Control Center room, which is a dedicated space within an industrial or commercial facility where Motor Control Centers (MCCs) are installed and housed.
MCC rooms are designed to provide a controlled and safe environment for the operation and maintenance of electrical motor control equipment.
Here are some key aspects and purposes of an MCC room:
Motor Control Centers (MCCs): MCCs are electrical cabinets or enclosures that contain motor starters, control devices, overload protection, and other components used to manage and control electric motors. MCC rooms house these MCC units.
Electrical Distribution: MCC rooms are typically located near the machinery or equipment they control to minimize the length of motor feeder cables. They receive electrical power from the main electrical distribution system and distribute it to the motors in the facility.
Control and Monitoring: MCC rooms provide a centralized location for operators and maintenance personnel to monitor and control the operation of motors and related equipment. They often feature control panels, displays, and operator interfaces.
Safety: MCC rooms are designed to comply with safety regulations and standards. They may have safety features such as fire suppression systems, ventilation, emergency lighting, and electrical fault protection to ensure the safety of personnel and equipment.
Protection: MCC rooms protect the motor control equipment from environmental factors, such as dust, moisture, and temperature extremes, that could affect their operation. They also safeguard against unauthorized access to sensitive electrical components.
Maintenance Access: MCC rooms are designed with sufficient space and access for maintenance and servicing of MCC units. This includes clearance around MCC cabinets and components to facilitate inspection and repairs.
Organization: MCC rooms are often organized and labeled to ensure that operators and maintenance personnel can quickly identify and troubleshoot issues with motor control equipment.
MCC rooms are common in industrial facilities, manufacturing plants, and commercial buildings where a significant number of electric motors are used for various processes and operations.
The design and layout of an MCC room can vary depending on the specific needs of the facility and the equipment it houses.
Motor Control Center Manufacturers
This industry, I mean MCC manufacturing, is very large to list all manufacturers. But let’s list some of the leading companies.
- Allen-Bradley automation
- General Electric International Company (GE).
- WEG Industries.
- ABB Automation company.
- Siemens Automation.
- Eaton Corporation.
What is the difference between MCC and PCC panels?
MCC (Motor Control Center) panels and PCC (Power Control Center) panels are both important components of electrical distribution systems in industrial and commercial facilities.
However, they serve different purposes and have distinct functions. Here are the key differences between MCC and PCC panels:
|MCC (Motor Control Center) Panels
|PCC (Power Control Center) Panels
|Control and management of electric motors.
|Distribution and control of electrical power to various loads and equipment.
|– Motor starters – Overload protection devices – Control devices (push buttons, selector switches) – Control transformers – Control circuitry
|– Circuit breakers – Switches – Relays – Busbars – Power meters – Protection devices
|Used to start, stop, control speed, and protect electric motors in industrial and commercial machinery.
|Serve as the central point for power distribution and control in a facility, routing power to various electrical loads.
|Typically installed near the machinery or equipment they control.
|Usually located in dedicated electrical rooms or substations, separate from the equipment.
|Enclosure types vary depending on environmental conditions (e.g., NEMA 1, NEMA 12, NEMA 4X).
|Housed in specialized enclosures designed for electrical protection and safety. Enclosure type varies based on application and location.
This table highlights the main differences between MCC panels and PCC panels in terms of their purpose, components, applications, location, and enclosure types.
What is the difference between switchgear and MCC?
Switchgear and Motor Control Centers (MCCs) are both essential components of electrical distribution systems, but they serve distinct purposes and have different functions. Here are the key differences between switchgear and MCC:
Primary Function: Switchgear is primarily designed for the protection, control, and isolation of electrical equipment in the power distribution system. It includes devices such as circuit breakers, fuses, switches, and relays to control and protect electrical circuits and equipment.
Voltage Levels: Switchgear can handle high voltage levels and is typically used for power distribution in medium and high-voltage electrical systems, such as those used by utilities and industrial facilities.
Applications: It is used for switching and controlling power sources, connecting or disconnecting electrical circuits, and safeguarding against overloads, short circuits, and faults.
Components: Typical components of switchgear include circuit breakers, disconnect switches, busbars, relays, and protective devices.
Enclosures: Switchgear is housed in specialized enclosures designed to protect against electrical faults and hazards, such as arc flashes.
Location: Switchgear is often installed in dedicated electrical rooms or substations, away from the machinery it controls.
Motor Control Center (MCC):
Primary Function: MCCs are designed specifically for the control and management of electric motors. They contain motor starters, variable frequency drives (VFDs), control devices, and other components necessary to operate motors efficiently and safely.
Voltage Levels: MCCs are typically used for low and medium-voltage motor control applications.
Applications: They are used to start, stop, control the speed, and protect electric motors used in various industrial and commercial machinery and processes.
Components: MCCs include motor starters (often combination starters), overload relays, control transformers, control circuitry, and sometimes VFDs or soft starters.
Enclosures: MCCs come in various enclosure types, including NEMA 1 (indoor), NEMA 12 (dust-tight), and NEMA 4/4X (watertight). The enclosure type depends on the environment where the MCC is installed.
Location: MCCs are typically installed near the machinery they control, often on the factory floor or in proximity to the equipment.
In summary, while both switchgear and MCCs play critical roles in electrical distribution and control, switchgear is primarily concerned with high-voltage power distribution and protection, whereas MCCs are focused on controlling and protecting electric motors in low to medium-voltage applications. Each serves a specific purpose within the overall electrical system.
What is a double-front MCC panel?
Double front MCC panel or back to back, is a panel with front and rear motor control sections.
It provides shorter length but harder access for maintenance. The use of both front and rear directions shortens the bus bar and the overall length of the MCC panel.
Unfortunately, the double-front MCC panel maintenance may be harder than a single-front one.
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