Automation Technology

Learn about an Innovative Approach to a New Motor Control Center

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Other significant design features include Allen-Bradley 141a busbars and MCS isolation modules. These components allow the motor starters to be configured in a modular fashion, so that they can be installed side by side (starters normally clip on to a “top-hat” rail). The MCS modules, in contrast, are plastic bases that clip on to a busbar, providing a direct connection and eliminating the need for wires. This design is not only simpler but also allows for an unclipping of the starters while the busbar is live (hot swap).

Rockwell Automation's solution included and in intelligent Motor Control Center (MCC) in Form 2 construction with Allen-Bradley CompactLogix PAC.
Rockwell Automation's solution included and in intelligent Motor Control Center (MCC) in Form 2 construction with Allen-Bradley CompactLogix PAC.
(Bild: Rockwell Automation)
The complete installation comprises a range of Allen-Bradley products including a Compact Logix programmable automation controller, PanelView 15 touchscreen HMI, three-component starters (MCB/contactor/E3+ overload relay), the 141a busbar, MCS ISO (isolating) modules with control plugs, PowerFlex 70 variable-speed drives and an open Device Net network connected to the PAC via Ethernet/Device Net bridges. The fixed-speed drives will be connected via twin Device Net networks (to allow duty/standby separation), with connection to the PAC via Ethernet/DeviceNet bridge modules — negating the need to install scanner cards.

Lower Costs, Improved Operability

The new design could bring numerous benefits for Severn Trent Water, NMC believes: The MCC Form 2 setup has a smaller footprint than a Form 4 construction, reducing both cost and size of the MCC itself, the building housing it and the base slab. The total saving in capital cost is 23 % compared to standard Form 4 construction. The use of Ethernet communications via Ethernet/DeviceNet bridge modules saves costs in connecting to the PLC. “The use of Form 2, busbars, MCS and ISO was seriously considered following a visit from Peter Plows from Rockwell Automation,” Chris Webb explains. “I went to Rockwell Automation’s UK HQ for a presentation and I left with a head full of ideas. I decided that the next time I attended an ICA COP meeting, I would present the technology. As a result, the group bought into it and it all moved forwards.”

Chris Webb adds: “The Ethernet connectivity deployed within the MCC is very useful and flexible and is almost certainly the way forward regarding control networks. Why put in a closed network when such a powerful open network is out there?”

“Rockwell Automation’s products are probably the easiest to use on the market,” he concludes. And more: “They are extremely versatile and well supported. Personal interaction is also open, friendly approachable and supportive.”

* The author is Solution Architect Process & Information Software at Rockwell Automation.

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