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 Busbar system, are segregated to Form 4 of BS EN 61439-1 and are sealed against personnel access for safety.
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, Transformers etc. all as required for the particular project.
Incomer sections 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.
 Part of one of the MCC rooms showing transformer enclosures - Cardiff Bay for Welsh Water |
 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 section undergoing Short Circuit Testing |
 Bridge unit spanning walkway |
Bridge unit spanning 2 MCC's |
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.
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| Typical Withdrawable Tray complete | Completed Withdrawable assemblies |
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| Special Changeover Section | Completed VSD unit |
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| Transformer, Incomer and Bridge | Completed and Installed |
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| Flood prevention measures | Ready for wiring |
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 are destined 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 has now started on site and you can follow the construction over the next year or so - it is due for completion in 2009. There is an article here with more information on the whole project and the concrete in particular.
There is also a Waterworld Article here with more details on the huge pumps employed. When complete you will be able to visit the station and see the pumping hall and our drives.
D.C. busbar Links - 1200KW Drive - output section (3 x units in parallel).
Ramping the Drive Modules in and out (Ramp by Rolla)
A Full workshop (Technical Control Systems - Leeds)
