When asked to tender for the six new motor control centre (MCC) switchboards needed for a major upgrade to a flour mill, specialist switchboard supplier EMS of Aylesbury found that equipment in Eaton's Moeller Modan range provided the best and most economical way of addressing the challenges associated with the project.
The equipment was needed for a flour mill in Tring, Hertfordshire, which is owned and operated by Heygates, Britain's largest independent miller. The mill processes over 100,000 tonnes of wheat each year, resulting in the production of around 76,000 tonnes of flour, most of which is supplied to bakers.
The task of upgrading the electrical equipment in this important mill posed two key challenges. The first was that the space available to accommodate the new switchboards was extremely limited. The second was that, as the mill operates continuously and downtime is costly, it was necessary for Heygates to be able to carry out maintenance and fault-finding work on, for example, individual motor starters, without shutting down the whole plant.
The experienced electrical design engineers at EMS knew from their work on previous projects that switchboards from Eaton's Moeller Modan range would provide a complete and cost-effective solution to both problems. While the Modan switchboards are available in a variety of configurations, for this application the engineers chose the fully withdrawable concept – MODAN W.
Because Modan W uses withdrawable and removable plug-in units, function modules can be exchanged even while the system is live, allowing a very high level of availability to be achieved. Also, the user-friendly design of the plug-in units facilitates handling and guards against operator errors. These features made it easy for EMS to satisfy Heygate's requirement for safe working on individual sections of the plant while the remainder was still operational.
In addition the Modan design offers a very high stacking density – up to 30 withdrawable units can be accommodated in each section – allowing the best possible use to be made of the very limited space available.
The versatility of the switchboards was another key issue in making them particularly suitable for this demanding project. Not only can they accommodate starters up to 200 kW and power outgoing sections up to 630 A, they are also readily adaptable to house other types of control and distribution equipment.
At Heygates, this flexibility allowed EMS to build into the switchboard sections containing Eaton's Moeller DF51 variable speed drives, DM4 soft starters and several 12-way distribution boards, as well as conventional starters ranging from 1.1 kW direct-on-line to 30 kW star-delta.
For ease of assembly and maintenance, all of the starters on the project used Eaton's Moeller xStart contactors and motor protection circuit breakers. The contactors and breakers were linked using the range's unique tool-less connector system. This not only substantially reduces the time needed for panel wiring, but also virtually eliminates the risk of wiring errors, thereby also saving time in testing and commissioning.
"Being able to accommodate virtually all of the equipment needed for the project within the motor control centres made it a lot easier for us to stay within the very tight space limitations imposed by the layout of the Heygates site," said Craig Walford, technical sales engineer at EMS.
"In addition, with Modan it was easy to achieve an IP54 ingress protection rating," he continued, "which is absolutely essential in a flour mill, where very fine dust is unavoidably present in the atmosphere."
Each of the six boards supplied for the project is a free-standing floor mounting assembly approximately 4 metres long, with an IP54 ingress protection rating. All of the boards are arranged to provide Form 4, Type 5 segregation between the functional units, and are supplied with type-tested assemblies in accordance with BS EN 60439-1.
"Thanks to the versatility and ease of use of Eaton's Moeller Modan boards, this whole project progressed extremely smoothly at every stage, from initial design and specification through to installation and commissioning," said Craig Walford. "The engineers and users at Heygates are delighted with the quality, appearance and performance of the new installation, and we at EMS will most certainly be continuing to use Modan on future projects."
