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Super efficiency for super-sized mill
Canfor’s super-sized Houston, BC, sawmill has been able to make maintenance on its sawboxes more efficient through the installation of a combination plug, receptacle and disconnect switch that allows the fast and safe making and breaking of electrical connections.

The 7.5 horsepower motors on the sawboxes of an Optimil double length infeed canter at Canfor’s Houston sawmill (above) must be removed frequently to carry out routine maintenance. Meltric’s switch rated decontactors (in blue) make the job faster and easier than rewiring each time.

By Jim Stirling

When you can slash the time it takes to do routine maintenance on a piece of sawmill equipment from hours to minutes, you take notice. When the means of doing that reduces a safety risk for maintenance staff and allows better utilization of mill tradespeople, the interest grows proportionately.

The accumulated advantages of reduced downtime and more production from such an initiative are the experience of Canadian Forest Products Ltd’s Houston sawmill in west central British Columbia. The time-saving, safety-boosting device that caught the Houston mill’s electrical staff’s attention is the Meltric Decontactor series of switch rated plugs and receptacles. The combination plug, receptacles and disconnect switch allow the fast and safe making and breaking of electrical connections.

The application in the Houston mill has been on 12 sawboxes on an Optimil double length infeed canter with chipping capabilities, says Kevin Trottier, electrical supervisor at Canfor Houston. The sawboxes typically require cleaning and routine operational maintenance about twice a month. What that process used to entail was getting an electrician to disconnect the wiring on the sawboxes so the millwright could do the cleaning and maintenance. Then the electrician had to return and re-wire each of the 7.5 horsepower motors. It took about three hours of an electrician’s time, says Trottier.

Now it takes a very few minutes. Millwrights can disconnect the motor, take the top off the sawbox, do the maintenance, put it back together and reconnect without having to wait for an electrician, he explains. The electrician is freed to do other work around the mill.

“We are always looking for opportunities to improve our efficiencies,” expands Trottier. “And I’d been looking for a long time for an alternative to low voltage external pilot circuits in terms of both costs and safety.”

He adds the sawdust in a mill application compounds the headaches with using a low voltage pilot circuit. The sawdust issue is itself compounded by the Houston mill’s reliance on a diet of dry logs killed by the mountain pine beetle.

Lumber made from this timber contains cracks and checks which can break or splinter during the mill’s high speed production processes.

The Decontactor series of switch rated plugs and receptacles are manufactured by the Meltric Corporation based in Franklin, Wisconsin. The company specializes in a line of industrial duty plugs and receptacles developed to address safety hazards associated with pin and sleeve and twist type devices. The company’s DSN models used at Canfor Houston have a 30 amp rating and handle motors up to 15 horsepower. Others in Meltric’s line can accommodate applications up to 200 amps and 60 horsepower.

Meltric says its Decontactors are designed to provide a secure connection through thousands of operations. Their solid silver and nickel contacts are designed to withstand wear, corrosion and oxidation. There are no complaints about the Decontactors’ durability at Houston where they have been working well for more than two years, reports Trottier.

He has plenty of ideas about other spots in the mill where the Decontactors could provide similar advantages to those reaped with the installation on the Optimil canter. The mill’s gang, for example, that processes 12-inch cants has eight motors on its infeed and eight more on the outfeed. But it’s the forest economy that has other applications on hold.

Canfor acquired the Houston mill in 1999 from Northwood Pulp & Timber. Since then, it has invested in the mill and boosted capacity to 540 million board feet of lumber annually, making it one of, if not the largest lumber producing mill in the world.