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November 2022
Motor maintenance is key in dirty industries

Motor maintenance is key in dirty industries

09 November 2022

Mining, steel making, pulp and paper mills are all extremely dirty industries. Each has a manufacturing process that creates build up and residue that can seriously damage, or even destroy, a manufacturing facility’s equipment, more specifically the motors that run that equipment. Understanding the different types of maintenance and how to preserve the motors in the equipment used in each of these industries is key.

Let’s consider a pulp and paper mill that uses recycled paper to produce new paper as an example. In the US, there are mills that don’t take the time to maintain their motors from a preventative standpoint. They allow their motors to run with built-up sludge and residue. This greatly reduces motor life due to the heat that is trapped under the thermal blanket that it created by the build-up, making the motors unstable and eventually fail. We will explain what it is they could be doing to not only test their equipment, but also keep it running for many years.

Pulp and paper mills are messy places. Because of this, unexpected downtime can occur when equipment is not tested and maintained properly. This can cost a mill thousands of dollars, in addition to motor repair costs when equipment fails, which could jack a repair cost up to three times what it should be if equipment was regularly maintained.

Different types of maintenance

Taking the time to examine your equipment and understand what type of maintenance program your facility should follow is key in keeping machinery up and running with little to no downtime. There are three different types of maintenance strategies that companies take:

  • Reactive maintenance: No program in place and running equipment to failure.
  • Planned or time-based maintenance: Equipment is serviced on a schedule, regardless of condition.
  • Proactive or condition-based maintenance (CBM): A maintenance strategy that monitors the real-time condition of equipment to determine what maintenance needs to be performed and at what exact time.

When it comes to the motors in the machinery at pulp and paper mills, proactive or CBM is really important. If preventative measures for electric motors are taken, like changing filters, cleaning fan blades, washing and lubricating the motors, then the motor and equipment will have a long lifecycle. However, if these measures are not taken, or other factors like excessive starts/stops or in an environment where the equipment operates is hot, wet or has caustic particulate that is ingested by the equipment’s motor fans, then the equipment and its motor’s lifecycle will be reduced significantly.

Knowing the rules

One rule of thumb, based on IEEE standard 101, if a motor runs 50°F hotter than 104°F (as the reference start point), then the motor life is cut in half. For example, if a motor is running at 140°F, it is running 36°F hotter than the referenced 104°F, cutting the original motor life expectancy from 30 years to 15 years. This is extremely important to companies that rely on motors for their operations.

When observing what is transpiring at some mills in the US, it is evident that the rule of thumb in not being followed. The thermal blanket created by the paper pulp caked on these motors is undoubtedly causing the motors to run at much hotter temperatures than they should be, which in turn, significantly decreases the life of the motors. It also increases the likelihood of fire in the facility. All of these things point to loss in time, money, and safety.

Cleaning off the pulp and testing the motors

It is never too late to start a maintenance program — regardless of whether it is preventative maintenance or predictive maintenance. Although a motor can be tested with sludge encasing it, it isn’t recommended to run equipment this way. The most important thing to do when equipment is encased in sludge is to first get the sludge off of it and out of the motor. It will not only be easier to test, but it will also ensure a longer life of the motor. This can be done by hosing it down, blowing off the debris or scraping off the pulp. Once this is complete, the motor testing can be performed.

Megger Baker Instruments offers a few different testers that can help perform various tests to help with this. This includes static testing which can be done with Megger Baker’s ADX model. This tester can identify issues in the connections in the motor, as well as check insulation to ground and turn-to-turn insulation. Insulation is directly affected by the heat created by the pulp thermal blanket. It can be easily identified as failing by using a static tester.

Dynamic testing can be performed using Megger Baker’s EXP model. This tester identifies issues with the power quality (what’s coming into the motor), some issues with the motor itself (rotor bar, for example), and the load connected to the motor.  In the case of motors running hot, this could potentially be identified with a few different tools within the dynamic tester, including trending.

Not a lost cause

Equipment coated with sludge does not need to be a lost cause. Megger Baker has a simple solution on how to test the motor equipment in a pulp and paper plant. By cleaning and testing the equipment, as well as having a maintenance strategy in place, is key to keeping it up and running for years to come.