Motor Control Center (MCC) Buckets Information
Motor control center (MCC) buckets are compact, partially-open enclosures that allow for the control part of a MCC to be removed and installed quickly.
MCC buckets are typically metal enclosures around one or two square feet in area, but can vary greatly in size depending on the functions and hardware included. The buckets are installed in a larger control center which drives a number of motors associated with a piece of equipment. They are powered by various panelboard and switchgear equipment, often from a separate cabinet.
There are many reasons to use an MCC bucket; they are used for ease of installation and to modernize components in a control center, for example replacing thermal overload relays with solid state versions. Companies specialize in manufacturing both new and replacement buckets that are the same physical size and contact layout of the older equipment. MCC buckets can simplify the installation of motor controls. Often a bucket contains all the necessary control components in one enclosure.
Buckets are designed for various type of power but are most often three phase AC as that is the most common power used in manufacturing facilities. They have bus connections on them to allow for quick connection to bus bars in the control center enclosure. Typically MCC buckets are for controlling a single motor and when placed in a control center cabinet along with other buckets they make up a motor control system.
Components in a bucket can include variable frequency drives, motor starters, contactors, circuit breakers, disconnect switches, overload relays as well as many other options. Buckets usually have a single shut off on the front that goes to the circuit breaker, this allows the user to shut off the power without opening or removing the bucket. Often buckets don’t have many or any other controls but some may have an interface to allow for adjustment.