Motor Control Centres

Motor Control Centres (MCC) are used to centralise the distribution of power and control to motors in the process industries. They comprise a sheet steel enclosure, a busbar system for the power and multiple compartments for the different control components. Rolla Ltd generally provide enclosures which are full height (over 2m) and contain an ASTA/KEMA certified Fault Rated Busbar system, are segregated to Form 4 of BS EN 61439-1 and are sealed against personnel access for safety. We also cater for small projects where busbars are not required with our 400mm deep UCC4 system.

Our Busbar systems are rated and certified up to 690V AC as standard but are usually connected to a typical LV network of 400V 3 Phase nominal. Neutrals are normally fully rated. Specialised voltages may also be used on some plants or offshore platforms.

Each MCC will have one or more incoming supply sections which are typically rated from 250A upwards, and multiple starter or drive sections as required for the duty. Other sections to be incorporated may include Power Factor Correction (PFC), SCADA, ICA, Telemetry, PLC, Small Power Distribution, Corner Units, Transformers etc. all as required for the particular project.

Incomer sections, including changeover systems, are usually fitted with free-issue devices including ACB’s, MCCB’s and fuseswitches, connected to the busbar system by Rolla, in accordance with our type tested arrangements.

Starter compartments contain all the protection and control gear for a single motor (Form 4), and can be either fixed pattern or withdrawable. Multi-compartment starters (group starters) are also used where lots of small motors need to be controlled and the Form 4 requirement can be relaxed.

Motor Control Centre On site Part of one of the MCC rooms showing transformer enclosures - Cardiff Bay for Welsh Water Control Panels of Various Heights Available in various sizes

Boards can be supplied with corner units and bridge sections for use where space is restricted - we have ASTA certificates at both 50KA and 80KA for such sections.

Corner Unit under test Corner section undergoing Short Circuit Testing Bridge between sections Bridge unit spanning walkway

Special Canopy Fitted Special Rear Access MCC with canopy fitted

Bridge 3 metres long

Bridge unit spanning 2 MCC's

Three off ACS800 Output Modules

ABB ACS 800 Drive Modules

Withdrawable units are used to save space and improve maintenance times on critical items of plant. We usually provide the trays pre-punched for the appropriate isolating device so that it lines up with the door handle, and any other punchings as required for the project.

Our withdrawable trays are equipped with 3 phase incoming power connectors at 130A, and either 50A or 130A outgoing connectors for DOL or Star-Delta starters. We also include 10, 20 or 30 auxiliary connectors rated at up to 20A. More withdrawable pictures here.

Withdrawable Tray - Wired
Complete Withdrawable Motor Control Centre
Typical Withdrawable Tray complete
Completed Withdrawable assemblies

Changeover Unit with Bypass Facility

Variable Speed Drive Completed

Special Changeover Section
Completed VSD unit
Transformer enclosure and bridge at Cardiff Bay
Motor Control Centre installed and working
Transformer, Incomer and Bridge
Completed and Installed
Motor Control Centre on Raised Plinth
Motor Control Centre before wiring
Flood prevention measures
Ready for wiring

1200KW Variable Speed Drive

1200KW Variable Speed Drive, 3.3m long.

6 off Identical to this have been built, each with 1250A ACB primary protection, and each using 8 off ABB ACS800 modules (2 x LCL, 3 x R8i in, 3 x R8i out) and 4 door safety interlocks.

These drives were built for the new St. Germans Pumping Station - the UK’s largest land drainage pumping station, designed to pump 100 cubic metres per second (or nearly 5 olympic swimming pools every 2 minutes!). Work started on site in 2009 and was completed in 2010. There is an article here with more information on the whole project and the concrete in particular.

There are details here with more pictures and details on the huge pumps employed. Now complete you are able to visit the station and see the pumping hall and our drives. More drives pictures here.

DC Busbar Links - Variable Speed Drive

D.C. busbar Links - 1200KW Drive - output section (3 x units in parallel).

Variable Speed Drive - Module Insertion

Ramping the Drive Modules in and out (Ramp by Rolla)

Smaller wall mounting units are also available (2 pump panels)

TCS Workshop with Rolla Enclosures

A Full workshop (Technical Control Systems - Leeds)