Two of those customers, a manufacturer of precast/prestressed concrete and a local utility company, couldn’t be more different - and yet have recently integrated micro PLC technology in order to maximize quality control and minimize energy consumption.

At the utility Woodstock Hydro Services Inc. (www.woodstockhydro.com), Glenile Electric’s industrial and automation designer Brad Mellick was faced with designing and commissioning an updated energy management system in an office building/truck garage built in 1961. With the help of local IDEC Canada Ltd. (idec.com/canada) technical sales representative Dennette Woodworth, his solution was to specify the IDEC microPLC at the heart of system.

As an HVAC contractor, Glenile’s natural inclination was to install a new HVAC system. This option was explored, but because it is expensive and there were budgetary concerns, more creative options were also explored. Mellick and Woodworth looked at the system requirements and came up with a bill of materials that would solve the customer’s energy problem and fit into their budget. Using IDEC PLCs, HMI, relays and power supplies, the system could be installed cost effectively to meet the budget and reduce energy cost significantly.

The office building had individual thermostats scattered through four floors to control the heating and cooling. For better control, a master control panel was proposed with an IDEC HG4F screen and a FC5A master PLC installed in the basement of the building. Three remote PLCs would be installed on each of the floors, connected together on an RS485 Dlink network. The individual room thermostats would be replaced with PT100 zone temperature controls to send temperature information to the PLC. Door interlock switches would shut down the heaters when shipping doors are open to prevent heat loss. Communication would also be required for a variable frequency drive (VFD) motor controller on the main air supply fan.

“By having all the power supplies in one panel, we only had to run 24 Vdc wire to the remote PLCs,” said Mellick. “This saved the additional costs of wiring 110 Vac at each remote location, along with the extra circuit breakers and conduit that would have been required, as well as an electrical code safety inspection.”

Mellick found IDEC’s WindLDR analog and digital device deployment software easy to learn. The system was set up at the shop and a bench test was completed before installation on site. Installation went smoothly with very few issues.

Set point temperatures are programmed into the master HMI control panel to conserve energy when no one is working in the building.

Derek Woodend, Meter/Substation supervisor at Woodstock Hydro, said the Glenile Electric system was “expected to provide significant savings - especially with the building’s electric heat - but had already exceeded expectations.”

For example, kWh energy consumption for July 2006 was billed at $4,159.48 compared to $3,125.84 for July 2007, a reduction of 25% even before cold weather. By contrast, prior to the Glenile system installation in May, the April 2007 Woodstock Hydro facility bill had actually increased 31% over April 2006.

Maintenance supervisor Duncan Hines at Glenile Electric customer Pre-Con Inc. (pre-con.com), a subsidiary of Lafarge, has to ensure that concrete building components for bridges and other structural elements meet stringent quality-controlled, CSA standards. Hines noted that a pair of RTDs monitors the concrete as it is curing in forms outdoors. That way, the temperature at the forms can be adjusted all year round by delivering more or less steam to adjacent pipes.

The controlled environment for producing the concrete is directed by a MicroSmart Pentra-based PLC and 12-in. touchscreen display from IDEC specified by Mellick. As part of a plant expansion at Pre-Con, his design mimics the controls of an older, more expensive Allen-Bradley system still in operation at the Woodstock facility.

“Glenile Electric has found the IDEC PLC products to be a reliable and cost effective solution for most industrial and commercial applications to compete in today’s market.”
www.idec.com/canada