Loparex Keeps Production Running Through Power-Supply Dips With Sag-Correction System

May 26, 2017
Voltage sags were costing Loparex in both downtime and waste. The company installed sag correctors to ride through the power-quality issues and annually save $90,000. Full article brought to you by Rockwell Automation. Visit The Connected Enterprise for more.  

Products That Stick

Loparex is one of the world’s largest producers of release liners, which are paper and film substrates that are coated with specialty silicones, polymers or other material. The liners are attached to a self-adhesive face stock and can be peeled off when the face stock is applied, either during manufacturing, such as for product labels, or in end-use applications.

Loparex release liners are used in products ranging from tapes and envelope liners to roof coverings that protect homes from the elements and transdermal medical products that deliver drugs through adhesive skin patches.

For more than a decade, the company’s 305,000-square-foot production facility in Hammond, Wisconsin, had been experiencing voltage sags several times per year that disrupted its largest production line.

A voltage sag is a drop of 10 percent or more in the nominal voltage and can occur in the blink of an eye. Brief as they may be, these sags can impact production equipment in many ways. For example, they can disrupt controllers and industrial computers, which require a low DC voltage in order to operate. They also can trip the relay in an emergency-stop circuit or create an under-voltage condition on a drive’s DC bus.

These events can result in production downtime, damaged electrical equipment, increased scrap and missed production targets. Perhaps even worse, an inability to diagnose these power issues can leave plant personnel all but helpless to understand and mitigate them.

Hoping to reduce the effect of these energy events, Loparex implemented a sag-correction system to help keep its top production line running through voltage sags.

Voltage Sags a Drag on Production

With the Hammond facility sitting at the end of an approximately 6-mile utility feed, Loparex knew its power quality was less than ideal. But it lacked a way to investigate its power-quality events.

To get a better grip on the voltage-sag problem, Loparex installed the Allen-Bradley® i-Sense® and i-Grid® intelligent network system from Rockwell Automation on its largest coating line. At about 250 feet long, the line includes tandem extrusion, in-line coating and slitting capabilities, and can run at speeds of up to 2,000 feet per minute.

Once implemented, the i-Sense power monitor transmitted the production line’s power-quality feed to the cloud-based i-Grid application, which collected and analyzed the power-event data before delivering it to plant personnel.

“We learned that even a sag event of less than 250 milliseconds and in the 80 percent power-quality range could take us down,” said Greg Weyer, engineering manager at Loparex’s Hammond facility. “These seemingly tiny instances could bring the whole line down or cause communications to go down.”

Each shutdown resulted in downtime that could last anywhere from 45 minutes to a few hours, depending on how long it took workers to clean up product and get the line moving again. And because partially processed products could not be recycled or recovered, each shutdown could result in anywhere from 10,000 to 15,000 feet of waste.

Weyer estimated that the sag-related downtime events cost the company about $5,000 on average when lost production time and waste were factored in. And given that the line was experiencing an average of about 20 sag-related downtime events per year in recent years, the energy events were annually costing Loparex about $100,000 on just one line.

Sag-Correction System

With data in hand that correlated the power-quality events to production issues, Weyer received the go-ahead to take corrective action.

A full backup power supply, like an uninterruptible power supply (UPS) system, would have been too expensive given the size of the production line. Instead, Weyer opted to use Allen-Bradley Dynamic Sag Corrector (DySC®) products from Rockwell Automation. The battery-free products use a double-conversion inverter technology to achieve up to five seconds of ride-through during short-term sags and momentary outages. They can be scaled from 0.25 kVA to 2000 kVA for either machinewide or facilitywide protection.

With the help of the i-Sense/i-Grid system, Weyer and his team identified the key control areas of the Hammond production line where power-quality events were causing the shutdowns. This helped to determine where to implement the DySC products.

The production line is comprised of seven integrated systems, each with its own standalone control system. Weyer and his team installed one DySC product in each of these control panels, and then an eighth DySC product on the air compressor that feeds the entire plant.

90 Percent Reduction

Weyer originally set a goal of enabling the production line to ride through 50 percent of voltage sags with the DySC products in place. They far exceeded that target, riding through about 90 percent of sags. That’s translated to about $90,000 per year in savings via reduced downtime and saved product.

“In the two years since we’ve implemented the DySC products, we’ve only had four or five sags take this line down,” Weyer said. “Without them, we would have experienced about 40 sag-related downtime events in that time period.”

Additionally, the air compressor that is integral to not only this line but also the Hammond facility’s seven other lines can now ride through nearly every power-quality event.

Weyer originally estimated the DySC system would pay for itself within two years if the 50 percent ride-through goal was met. Given the better-than-expected performance, however, the system recuperated its cost in less than one year.

Now, Weyer has plans for bringing the DySC system to other parts of the Hammond facility.

“We’re looking at implementing the DySC products on our two blown film lines,” Weyer said. “Voltage sags can result in a number of fault issues on these lines, which can be a headache to recover from. They also have the potential to damage equipment and electronics. We see the DySC products as helping us address both of these issues.”

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