Editor's Choice

Quality test tools save costs at pulp and paper mill

April 2024 Editor's Choice Maintenance, Test & Measurement, Calibration

‘Rob’, an electrical engineer at a US paper mill, knows those challenges well. He’s responsible for electrical and electronic issues related to two large tissue machines that generate several tons of paper towels an hour. Installing and troubleshooting those systems was great preparation for the gargantuan tissue machines he works on today. Each machine is run by coordinated drive systems with about 12 drives and motors, plus auxiliary equipment that adds another 100 motors or so to each machine. The motors range from half a horsepower to a 6000 horsepower behemoth.

“I troubleshoot everything from variable-frequency drives (VFDs) and motors to programmable logic controllers (PLCs) and instrumentation. We’ve got a lot of valves, a lot of instrument sensors and a lot of coordinated drive systems,” Rob says.

On any given day, Rob gets trouble calls ranging from nuisance issues to potential catastrophic failures.

Starting with the basics

Motor and drive problems are the most common calls. “Normally your first check is to do an insulation check on the motor and wiring to make sure it’s not shorting to ground somewhere,” Rob explains. “If the insulation check is reading low, that’s usually a dead giveaway that it’s time to change out the motor.”

Few things are as disposable as paper towels. But the next time you nonchalantly toss away (or compost) a paper towel, keep in mind that there’s a lot more to it than meets the eye. Paper towels are manufactured through a finely tuned system of electrical, electronic and mechanical components. Coordinating all those components and keeping them running productively 24 hours a day is challenging, to say the least.

Sometimes, however, the problems are a bit more complicated. “If you’ve got a sporadic fault or the motor is tripping out because it’s pulling too many amps or it doesn’t have enough resistance, you have to investigate further,” he adds.

Because the machines run 24 hours a day, troubleshooting is done with the machines running, if at all possible. “If it’s a smaller component, a lot of times you can isolate it and just fix that one area while the machines are running,” Rob notes.

The environment in a pulp and paper mill is not easy on tools or people. It’s wet, steamy and dusty. Technicians have to climb ladders to reach some of the equipment, so tools need to be easy to carry, rugged, and above all, reliable.

Rob has found that Fluke tools perform well in that environment. He was first introduced to Fluke by his father, who is an electrician for a hydroelectric power company. Today the list of Fluke test tools Rob uses reads like a mini catalogue – about 18 items at last count.

Responding to sensitive VFDs

One tool Rob is almost never without is his Fluke 87V DMM (digital multimeter). Whether he’s doing first-line troubleshooting or delving down into more complex problems, the 87V is usually the first tool he turns to. A case in point: one night a VFD-controlled motor kept tripping. Technicians were concerned that they’d have to replace the motor. That would have taken about eight hours plus another two hours to restart the machine.

“Using my trusty Fluke 87V, I was able to determine that the motor was fine, but the real issue was a 5 V instrument supply module,” Rob recalls. “Older VFDs have a very low tolerance for these modules. The 87V was reading 4,77 V on the supply module. The lowest possible voltage this drive can handle from the supply is 4,8 V.” The solution was to replace the communication power supply board, which cost about $300 and took just 15 minutes.

“Had it not been for the accuracy of the Fluke meter we probably would have changed the motor and still been stumbling around trying to find the problem. It’s a real testament to the accuracy of these meters and the trust we place in them every day,” he adds.

In a similar situation, Rob was able to find a subtle problem in a motor lead with a Fluke thermal imager. In this case, a VFD kept faulting out after technicians had upgraded the drive and motor. “We checked the wiring with the insulation tester and found a slight degradation, but it was still within the acceptable threshold,” Rob explains.

They changed the VFD, but the problem continued. They were just about to change the motor when Rob decided to bring out a Fluke infrared camera. “We scanned the motor leads with the camera and the centre phase lead lit right up,” Rob recalls.

It turned out that technicians had left the old wiring when they upgraded the VFD and motor. “The insulation was still within our spec, but the new VFD was far more sensitive than the old one and it detected the slight insulation breakdown and kept kicking out,” he adds. The wiring and the problem were duly solved.

The following are some of Fluke’s instruments that make up Rob’s toolbox:

• Fluke 87V DMM industrial multimeter: delivers accurate frequency measurements on adjustable speed drives, and captures transients as fast as 250 µs.

• Fluke Ti 480 infrared camera: a 640 x 480 thermal camera that is perfect for professionals, with high-performance features and increased sensitivity to visualise temperature differences.

• Fluke 754 documenting process calibrator: calibrates critical safety instrumentation on the tissue machines. “Each machine has a set of critical sensors. A couple of times a year we verify the calibration on the pressure transmitters for those sensors with the 754 and the pressure modules,” says Rob.

• Fluke 773 milliamp process clamp meter – determines whether a sensor is really bad or whether the card is just not generating the 4-20 mA output. “You can put the 773 on the PLC and it’ll tell you exactly what it is outputting, so you can tell whether you’ve got a blown channel or if the instrument is shot,” Rob explains.

For more information on this product contact https://bit.ly/3ET34ZC


Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Prioritising arc flash safety
Comtest Electrical Power & Protection
Comtest has developed a range of thermal imaging and wireless testing tools from Fluke, designed to ensure safety is the top priority for engineers working in potentially dangerous arc flash zones.

Control architecture leads to faster, easier product development for refrigeration
Opto Africa Automation Editor's Choice IT in Manufacturing
What’s the secret to providing superior service and staying competitive in a changing market? You might learn something from ALTA Refrigeration’s experience. Over ten years, it transformed itself from a custom engineering services company into a scalable industrial equipment manufacturer, using an edge-oriented control architecture to manage a growing installed base.

Step into the visual factory
Turck Banner Southern Africa Editor's Choice Electrical Power & Protection
At Banner, the visual factory comprises three key applications for lighting and indication in industrial settings. These applications include the ability to help machines and workstations quickly communicate their status to people nearby, to use light to guide workers to perform certain tasks such as part picking, and to provide illumination for work areas and tasks.

Quality gearboxes for irrigation
SEW-Eurodrive Editor's Choice Motion Control & Drives
SEW-EURODRIVE is offering a complete gear solution for centre pivot irrigation systems as an original equipment manufacturer (OEM) closer to South Africa’s farming sector.

No more shocking, inaccurate insulation testing
Comtest Electrical Power & Protection
Fluke has introduced the Fluke 1535 and 1537 2500 V insulation resistance testers, engineered to simplify frontline troubleshooting, whether on the factory floor or working in the field at a solar installation.

AI in manufacturing: a process engineer’s perspective
Editor's Choice IT in Manufacturing
The expert will tell you what to do, the philosopher will tell you why to do it, and the engineer will get on and actually do it. As the hype around AI intensifies, the number of ‘experts’ is increasing exponentially. In contrast, the number of engineers who actually know how to implement AI technology remains small.

Seaward testers power PV specialists
Comtest Electrical Power & Protection
One of Asia’s leading clean energy specialists, Solarvest, uses the latest electrical safety test equipment to ensure the solar photovoltaic (PV) installations it services and maintains operate at peak performance levels.

Cable locator for failsafe cable fault diagnostics
Comtest Electrical Power & Protection
Accidentally hitting a power cable during a project can lead to costly repairs and create seriously hazardous safety situations. The Amprobe UAT-600 series locating kit from Comtest comes complete and ready for use with a transmitter, receiver, test lead kit, batteries and additional fuses, all in a mobile, protective duffle bag.

Loop signature 22: How cyclical disturbances affect a control loop
Michael Brown Control Engineering Editor's Choice
When tuning noisy loops, we recommend in our courses that one should eliminate the noise by editing it out, so the tuning will be done only on the true process response, free of any noise. The controller is controlling the process, and is not controlling the noise.

High-performance motion control for teabag packaging machine
Beckhoff Automation Editor's Choice
Teepak relies on PC-based control and drive technology from Beckhoff to set new benchmarks for speed and precision in its teabag packaging machines.