Low Voltage Motor Control Centers: Enabling Efficient Control of...

Low Voltage Motor Control Centers: Enabling Efficient Control of Motors in Industrial Facilities

Posted 2024-02-07 12:08:01

What is an LV MCC?

An LV MCC consists of modular sections containing electrical components such as circuit breakers, contactors, motor starters, overload relays, and other devices necessary for controlling, protecting, and distributing power to groups of fractional-horsepower and small three-phase induction motors. The main components of an LV MCC include:

- Incoming section: Includes the main disconnect, branch circuit breakers, and other components for connection to the main power source.

- Individual motor control sections: Each section controls power to a particular motor and contains equipment like motor starters, overload relays, push buttons/selector switches, pilot lights, etc.

- Wiring gutters and buses: Provide interconnection between sections and components through bus bars running horizontally and vertically.

- Enclosure: Housed in a floor-standing, dead-front sheet metal cabinet for operator safety and environmental protection.

Benefits of LV MCCs

There are several key benefits that LV MCCs provide over individual motor control boxes including:

Centralized Control
An LV MCC centralizes control and monitoring of multiple motors through a single enclosure which provides safety, space savings, and easier access compared to dispersed controls. Operators can start, stop, or monitor motor operations from one centralized location.

Wiring and Cost Savings
Consolidating motor controls leads to reduced wiring requirements and costs compared to discrete control boxes for each motor. Fault diagnosis and routine maintenance are also simplified through centralized troubleshooting points.

Flexibility and Expandability
Low Voltage Motor Control Center MCC modular construction allows easy addition or removal of motor sections as process requirements change over time without disrupting other sections. Spare sections can be added for future growth needs.

Improved Reliability
Key components like circuit breakers, contactors, and controls are factory-engineered in an MCC for higher reliability than field-assembled controls. Redundant sections can take over motor loads if a section fails.

Applications and Components of an LV MCC

LV MCCs are commonly used in various industrial and commercial facilities to control equipment such as:

- Pumps: For water, sewage, cooling systems etc.

- Conveyors: For material handling in factories, warehouses, mines.

- Compressors: For pneumatic processes in manufacturing plants.

- Crushers/Mills: In mining, cement, aggregate operations.

- HVAC Equipment: Fans, air handlers, chillers, cooling towers in large buildings.

Typical components in an LV MCC include:

- Contactors: Used for on/off control of motors.

- Overload relays: Provide motor overcurrent protection.

- Circuit breakers: Primary overcurrent protection device.

- Push buttons/ selector switches: For manual motor control.

- Pilot lights: Indicate control status like Run, Stop, Close etc.

- Control transformers: To step down voltage for low-voltage control circuits.

- Wiring gutters and bus bars: Interconnect sections and components.

- Input and output terminal blocks: For power and signal connections.

- Nameplates and directory cards: To identify equipment characteristics