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Wiring system simplifies refrigeration project

Edited by the Engineeringtalk editorial team Mar 3, 2008

Greencold's was able to use a single panel to control a three-zone commercial refrigeration system, reducing the wiring cost and complexity.

Moeller Electric's SmartWire panel wiring system has made it possible for Greencold of Kettering to use just one control panel instead of the three originally planned.

The company was also able to eliminate the need for a costly PLC and to dramatically reduce panel wiring time.

In addition, a Moeller MFD-Titan operator terminal has allowed Greencold to provide the system with a greatly enhanced and highly intuitive user interface, with no increase in cost.

Greencold's project involved a three-zone commercial refrigeration system.

In the past, the company would have used a separate control panel for each zone to house the motor starters associated with that zone.

The operator interface would have been provided by pushbuttons and indicator lamps on each of the panels.

"When we saw the SmartWire system, which replaces most of the control wiring in the panel with convenient pre-assembled plug-in leads, we quickly realised that it would enable us to put all of the equipment in one panel, without having to worry about the amount and complexity of the wiring", said Greencold Managing Director, Simon Andrew.

"That would give us an immediate substantial cost saving, as one slightly larger enclosure costs far less than the three small ones".

"And there was another big bonus - since SmartWire means that the starters connect directly to the PLC or similar control device rather than via conventional I/O, we no longer needed a PLC with large I/O capacity and we were able to use Moeller easy intelligent relays instead".

"This resulted in further big cost savings".

Other benefits of SmartWire included the automatic provision of overload and contactor status information to the easyRelay without the need for additional control wiring.

This made it straightforward to devise a program that would alert the plant operator to fault and alarm conditions.

In the final design, a compact control panel measuring just 1600 x 1000 x 400mm was fitted with 17 direct-on-line starters, with ratings of up to 15kW, from the Moeller Electric xStart range.

All of the starters were equipped with SmartWire interface units that clip into place in the same way as an auxiliary contact block.

In addition the panel contained the easy800 and easy618 intelligent relays, used to provide overall control.

For the system's operator interface, Greencold selected another product from the Moeller Electric easy range - MFD Titan.

This small, low-cost unit is capable of displaying user-programmable text messages and graphics and it connects directly with easyRelays.

By using the MFD Titan in place of conventional indicator lamps, Greencold was able to provide the system operator with clear, straightforward messages in plain English, giving details of plant status and fault conditions.

Further, the Greencold engineers have also arranged for the MFD Titan display backlight to flash when an alarm condition occurs, ensuring that problems receive prompt attention.

"While many of the benefits of SmartWire only became apparent after we started to look at the system in detail, there was one benefit we expected right from the outset, and that was a reduction in wiring time" Andrew said.

"We weren't disappointed - I've now analysed the timesheets for the job and the time saved was 25% on wiring and 10 less pages of drawings, making about a 33% time saving in total".