Archive | Motors & Drives

69

7:42 pm
April 13, 2017
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Top Tips For Maintaining Air Compressors

Use these tips to improve air-compressor performance and increase uptime.

Use these tips to improve air-compressor performance and increase uptime.

Air compressors and their output are valuable assets on which countless plants depend for efficient daily operations. Regular attention to and proper management of the health of these critical equipment systems can save time and money in all manufacturing systems.

John Skalka, service manager for Sullair (Chicago) offers several tips for maintaining your site’s air compressors. According to Skalka, following these procedures to help monitor and maintain air-compressor performance can result in reliable equipment and reduced downtime.

—Jane Alexander, Managing Editor

Maintain filters and separators.

Proper maintenance of a compressor’s consumable filters and separator elements will not only help to ensure maximum unit uptime, but also maximize its efficiency and performance.

Air intake and oil-filter maintenance should be conducted every 2,000 hr. Monitor the oil filter for contamination and wear metals, leading indicators that air-end maintenance is required.

Air/oil separator elements should be changed every 8,000 hr., along with compressor fluid. Proper air/oil separator maintenance will ensure oil carryover stays within the manufacturer’s specifications.

Remember that use of OEM service parts and lubricants in compressor maintenance will help ensure optimal equipment performance.

randmSample oil.

Regularly acquiring and analyzing oil samples helps monitor the condition of the compressor lubricant, as well as the unit itself. A robust oil-sampling and monitoring program will alert the user to fluid degradation resulting from increased viscosity, ingestion of chemicals or particulate, and high water content. It can also identify the presence of wear metals, which is a sign of bearing degradation, prior to catastrophic failure.

Oil-condition monitoring makes it possible to change the lubricant only when necessary to maintain peak performance. Samples should be drawn quarterly, during routine service maintenance on a compressor.

Remember to always draw your samples through a clean oil-sample port or from the center of the oil sump. Doing so will ensure that the results are free from particulate contamination.

Keep variable-speed drives clean.

Many of today’s compressors are equipped with a variable-speed drive (VSD) that increases efficiency and reduces energy consumption. While VSDs are electrical components, they are not completely maintenance free.

Most VSDs contain cooling fans and heat sinks that can accumulate dust and dirt during regular operation. Maintenance activities will help them run cooler and prolong their service life.

Eliminate the guesswork.

For plants that are unable to ensure regular compressor maintenance with in-house resources, outside support is available. Check with your local air-compressor sales and service center about plans that allow skilled, factory-trained technicians to routinely service your compressor(s) and related air-system equipment.

Finally, keep in mind that proper maintenance will help you realize years of reliable service from your compressor. MT

Sullair, part of Accudyne Industries (Luxembourg and Dallas, accudyneindustries.com) has been developing and manufacturing air compressors since 1965. For more information, visit sullair.com.

583

2:58 pm
March 13, 2017
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Keep Stored Gear Reducers Service Ready

When gear reducers and other capital spares are improperly prepared for storage, their service readiness can be seriously compromised.

When gear reducers and other capital spares are improperly prepared for storage, their service readiness can be seriously compromised.

Are your statically stored gear reducers service ready? That’s the first of several questions from Dillon Gully of Motion Industries (headquartered in Birmingham, AL, motionindustries.com). He has good reason for asking. In conducting borescope inspections of statically stored internal-gear reducers for customers, Motion Industries personnel discovered as many as one-third of these assets sitting on shelves in a failed state.

Next questions: Are you willing to gamble the OEE (overall equipment effectiveness) and profitability of your facility on gear reducers and, for that matter, other capital spares that might not be service ready? What would you tell your boss if a critical spare were to fail within mere hours? Think this scenario doesn’t apply to you? How can you be sure? Gully offers some advice for achieving peace of mind.

— Jane Alexander, Managing Editor

Effective management of capital spares involves up-front identification of these assets and making sure they are in service-ready condition prior to preparing them for long-term storage. Unfortunately, many operations don’t follow through on this process once purchased units arrive on site. According to Gully, these steps are the only way to support the reliability of stored spares.

Capital spares can be defined as any item that is critical to production, promotes safety, decreases downtime, and/or prevents environmental issues. Gear reducers certainly qualify. The best way of verifying that these assets won’t fail as soon as they’re put into service is to inspect them before they are stored away—perhaps for years. Minimally invasive borescope inspections are a particularly good inspection method.

In a borescope inspection of a gear reducer, a camera scope visually inspects the condition of bearings, gearing, and internal components. The procedure can be accomplished through a plughole, which prevents contamination of an asset, if it is, indeed, ready for service. (Compared to the cost of replacing a failed bearing, costs associated with borescope inspections are also minimal.)

randmStorage planning

While information gleaned from borescope inspections can be used to confirm service readiness—or help identify steps for making a spare service ready—it can also help determine how to prevent these units from improper storage.

Corrosion, i.e., rust and contamination, are two, of many, causes of failure in gear reducers. When borescope inspections identify the presence of these failure modes, steps can be taken to correct them before the equipment is put into storage, as well as prevent those problems from recurring during storage.

Once a plan to prevent failures in stored spares is developed and implemented, it should be consistently followed. Every unit that will be stored, for whatever period of time, should be carefully protected. Preventing rust and contamination is a great start in protecting asset reliability and, thus, ensuring service readiness.

An ongoing process

Keeping stored spares in service-ready condition requires management accountability. Someone must be assigned responsibility for these assets, and expectations should be clear and realistic. It’s the responsibility of that designated person to ensure all spares are properly prepared and maintained. Identifying failed spares and bringing them back to service-ready condition is an ongoing process. As Dillon Gully emphasizes, “It should not be done one time and then forgotten.”

This plan for reliability can lower the probability of failure and bring a welcome degree of certainty regarding your stored gear reducers and other capital spares. MT

Working as an analyst for Motion Industries’ service center in Pensacola, FL, Dillon Gully has been conducting vibration and borescope inspections and managing capital spares for three years. For more information on these topics, visit motionindustries.com or bearings.com.

268

3:56 pm
February 8, 2017
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How to Start a Predictive Maintenance Program

IIoT motorsDevice and equipment advances, on display in our MT IIoT web section, is past the early adoption stage, but operations and maintenance (O&M) teams are still wrapping their arms around predictive maintenance programs. A recent interview with ARC Advisory’s Ralph Rio via SAP’s Enterprise Asset Management discusses this very issue and more.

Excerpt below:

Q: So how do people begin moving toward predictive maintenance – how do they get there?

Ralph Rio: The first thing people need to do is to educate themselves to understand what is available from a technology standpoint. People just entering this area are no longer “early adopters” so there is plenty of information out there. Get comfortable with the platforms and the business processes.

Sometimes technology education is coming from your machine builder (OEM) with improved data acquisition capabilities. From this post, “Are Smaller IIoT Applications The Next Wave for End Users?” and discussion with Erl Campbell at Aventics, MT found out how this is working:

“By actually monitoring the spool position, the machine can track exactly how each valve performed during a motion cycle: where that valve started, whether it fully shifted or only partially shifted, and its final position. These data points help machine builders and end-user operators correct issues that may affect overall packaging quality and integrity,” the white paper states (written by Erl Campbell.

Campbell added in a recent interview that the company is working on whether the (valve) reliability data should communicate with the factory floor or maintenance. Is it going to be some kind of wireless communication or will techs plug into the manifold and download that data?

>> For more on how to create a predictive maintenance program with Ralph Rio

1601Iot_logoFor more IIoT coverage in maintenance and operations, click here! 

225

9:40 pm
January 13, 2017
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Properly Align Variable-, Fixed-Pitch Sheaves

Aligning sheaves on equipment with multiple V-belts is more complex than aligning them on machines designed with single belts.

Aligning sheaves on equipment with multiple V-belts is more complex than aligning them on machines designed with single belts.

Variable-pitch sheaves are frequently used in air handlers. According to a blog post by Stan Riddle of VibrAlign (Richmond, VA, vibralign.com), they allow design engineers to increase or decrease the speed of the driven machine and, thus, provide:

• changes in motor amp draw to maximize efficiency

• increased or decreased static pressure and air flow.

Normally, a design engineer will specify the use of a variable-pitch sheave on the driver and a fixed-pitch sheave on the driven machine.

Performed on a single-belt machine, proper sheave alignment is simple, if a good sheave-alignment tool is used. When multiple belts are used, as they often are, proper sheave alignment can become more complex. A variable-pitch sheave can be adjusted to increase/decrease the sheave diameter. However, doing so also changes the sheave width, depending on the adjustment.

In his post, Riddle referred to a customer who was attempting to perform a sheave alignment on an air handler. The unit’s motor had a variable-pitch sheave, but the fan sheave was fixed. The customer stated that he could align one belt, but not the other.

As Riddle described it, the customer was struggling because the width of the fixed-diameter sheave was 1 5/8 in., but the width of the variable-pitch sheave was 2 3/8 in. Consequently, only one set of grooves could be aligned, meaning the other was out of alignment.

The key to properly aligning a variable-pitch sheave to a fixed-pitch sheave on equipment with multiple V-belts is to split the difference between the diameter widths of the two sheaves. In this example, splitting the difference between sheave-diameter widths of 2 3/8 in. and 1 5/8 in. would result in a 3/8-in. offset at each groove.

The key to properly aligning a variable-pitch sheave to a fixed-pitch sheave on equipment with multiple V-belts is to split the difference between the diameter widths of the two sheaves. In this example, splitting the difference between sheave-diameter widths of 2 3/8 in. and 1 5/8 in. would result in a 3/8-in. offset at each groove.

The solution

Riddle wrote that the solution to the customer’s problem was simply to split the difference between the width of the two sheave diameters, as shown in the following equation:

2 3/8 in. – 1 5/8 in. = 3/4 in. ÷ 2 = 3/8 in. offset on each groove

randmRiddle also noted that it’s important to keep in mind this approach will probably not align the components sufficiently to eliminate sheave and belt wear. In fact, such wear can’t be eliminated. Still, when it comes to aligning multiple V-belts on an equipment system, splitting the difference between the diameter width of a variable-pitch sheave and that of a fixed-pitch sheave to which it is aligned will make the belts wear evenly.

Variable-pitch sheaves are normally used to balance a system and achieve proper static pressure and speed. When that’s determined, according to Riddle, the variable-pitch sheave should be replaced with a fixed-pitch sheave of the proper diameter to match the desired speed and pressure. Once both sheaves are fixed-pitch, proper alignment can be achieved. MT

—Jane Alexander, Managing Editor

Stan Riddle, a technical trainer for VibraAlign, has spent more than 36 years aligning industrial machinery. For more information from him and other technical experts with the company, visit vibralign.com.

417

8:05 pm
January 13, 2017
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What’s Three Minutes of Motor Testing Worth?

Personnel at the motor-distributor’s service center used an AT5 to perform a de-energized, non-destructive motor-circuit-analysis test on the hospital’s failed motor. This type of analysis evaluates the condition of electric-motor connections, stator, and rotor.

Personnel at the motor-distributor’s service center used an AT5 to perform a de-energized, non-destructive motor-circuit-analysis test on the hospital’s failed motor. This type of analysis evaluates the condition of electric-motor connections, stator, and rotor.

A non-destructive technique offered payback by determining the root cause of a critical, repeatedly failing hospital motor.

A motor distributor in The Netherlands provided a 17-kW, 400-V motor to a local hospital in 2015. The hospital rented a portable crane to install the motor on the roof, where it was used to operate a fan. In the spring of 2016, the motor suddenly failed.

Challenge

When the motor first stopped running, the hospital’s maintenance technician had reset the unit’s variable-frequency drive (VFD). Although the motor restarted, the VFD shut it down once again.

The technician then performed an insulation-to-ground test and determined the motor winding wasn’t shorted to ground. Using a digital multimeter, he measured phase resistance and learned the phases weren’t open. Since the motor testing tools indicated a “good” motor, a decision was made to replace the VFD.

After the new VFD was installed, the motor started, but, much to the technician’s chagrin, didn’t continue running. It was at this point that the hospital reached out to the motor distributor, which promptly dispatched a technician from its service center to test the motor.

The service-center technician used a meg-ohm meter and DMM to determine that the motor wasn’t grounded and the phases weren’t open—the same as the previous findings by the hospital’s maintenance technician. Given these results, the decision was made to replace the motor. The new unit started and operated normally, confirming the new VFD was working as intended. The “suspect” motor was sent to the distributor’s service center for a more thorough inspection.

This figure shows the stator and rotor signatures from the motor-circuit analysis report, with phases listed at the top of the image.

Fig. 1. This figure shows the stator and rotor signatures from the motor-circuit analysis report, with phases listed at the top of the image.

Solution

At the service center, personnel used an All-Test Pro 5 (AT5) to perform a de-energized, non-destructive motor-circuit analysis (MCA) test on the failed unit. This type of test evaluates the condition of motor connections, stator, and rotor.

Using the AT5, connections were made to the three phases of the motor and a static test was performed. Next, the motor shaft was manually moved during the dynamic portion of the three-phase test. At the end of the test the instrument indicated the results shown in Fig. 1. This testing made it clear phase 2-1 (shown as “21” in the figure) had the problem.

Lessons learned

Owners/operators can reduce maintenance costs. A 17-kW, 400-V motor is not expensive, but when it is mounted on a roof and the owner has to rent a crane to lift that motor for installation and removal, the owner’s maintenance cost can become quite high. Had the hospital’s maintenance team used an effective motor-circuit-analysis device, they would have discovered that the motor was the bad actor, not the VFD. Many hours and dollars were wasted by ordering and installing a new VFD that had not been the true cause of the problem.

Distributors and suppliers can improve quality assurance. Motor distributors and suppliers should implement an additional quality-control measure prior to delivering new or off-the-shelf motors to their customers. Spending a few minutes to check the condition of motors will help distributors and suppliers avoid warranty issues and increase customer satisfaction. MT

To learn more about motor-testing tools and techniques from All-Test Pro (Old Saybrook, CT), visit alltestpro.com.

400

6:02 pm
December 22, 2016
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Understand How Temperatures Affect Gearboxes

Environmental factors can significantly affect gear-drive service life and maintenance costs. Temperature and temperature variations are at the top of the list.

Environmental factors can significantly affect gear-drive service life and maintenance costs. Temperature and temperature variations are at the top of the list.

Understanding the impact that the environment can have on the long-term well being of gearboxes is key to keeping them healthy. According to experts at Philadelphia Gear (philagear.com, King of Prussia, PA), environmental factors can significantly influence gear-drive service life and associated maintenance costs. A white paper from the company offers tips on how to deal with several of those factors, including temperature and temperature variations.

When choosing lubricating and cooling oil for a particular gear-drive application, consider viscosity under normal and “cold iron” conditions. The viscosity must be capable of providing adequate oil film to support gear-tooth and bearing loads under all operating conditions. When a gear drive is in the “cold iron” state, viscosity must be low enough so that during the unit’s operation, the splash-lubrication or force-feed lubrication system is capable of distributing the proper amount of oil to where it’s needed. If oil is too thick (due to the cold), there may be no splash, or the pump in a force-feed-lubrication system might stall, thus failing to supply oil to critical surfaces.

Several oil characteristics must be taken into account when selecting products for specific applications and temperature differentials. Some formulations have a flatter temperature index than others, meaning that, as oil temperature increases, viscosity will decrease at a lesser rate than comparable fluids. For example, synthetics have a flatter temperature index than mineral-based oils and, at a low temperature, will be less viscous than similar-viscosity mineral-based products.

Many locales, of course, experience severe temperature swings from summer to winter that can dramatically affect oil viscosity. Sites in such regions should change to different-viscosity products as seasons change. Oils that aren’t changed out seasonally could thin to a kerosene-like consistency in severe summer heat, and thicken to a molasses-like substance in frigid winter cold. Either scenario puts gear drives at risk. (NOTE: To help overcome environmental extremes, oil heaters are often employed to maintain a minimum oil temperature of 40 F to 50 F during colder months, and air-to-oil or water/glycol-to-oil coolers are used to control oil operating temperatures during extreme heat.) MT

randmMore Points to Ponder

When gear operation generates higher-than-normal operating temperatures, mineral-based oil can break down and lose some of its lubricating capability. Over time, this deterioration can cause the fluid to separate into its constituent organic parts, i.e., carbon, hydrogen, and oxygen in various chemical combinations. In such cases, the carbon manifests as fine grit that can be introduced into the oil. If this condition persists and the sludge approaches the thickness of the oil film between gear and bearing components, a loss of film can be expected. This situation, in turn, could result in metal-to-metal contact between gears and bearing components, eventually leading to gearbox failure.

Extreme Pressure (EP) mineral oils, in particular, contain additives such as phosphorous and sulfur, that enhance the products’ ability to support load, but, when broken down, introduce additional, potentially corrosive and abrasive, materials into the mix. Thus, when using EP oils, it is extremely important to monitor the oil through periodic sampling.

While the additives in EP products increase load-carrying capacity, they can be depleted over time. In that event, such oils no longer exhibit their original load-carrying capabilities. How can you tell if this is happening/has happened? Extended gearbox operation with EP oil that has lost its load-carrying capabilities can result in gear-tooth overload symptoms such as pitting.

— Jane Alexander, Managing Editor

For more information from Philadelphia Gear’s experts, and/or to request a copy of  “The Impact of Environmental Conditions on Gearbox Lifecycle,” (the white paper on which this article is based), visit philagear.com.

206

5:55 pm
December 22, 2016
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Gaps in Your Motor Reliability Program?

Quality control, trending, and troubleshooting are three keys to a successful motor-reliability program.

Quality control, trending, and troubleshooting are three keys to a successful motor-reliability program.

Businesses invest millions of dollars in what they believe will be a fail-safe maintenance program for their electric motors, according to Noah Bethel, vice president, Product Development for PdMA Corp., Tampa, FL. Regular tests are scheduled for each motor; engineers dutifully record the data, when required, and then move on to the next motor.

Collected data is meaningless unless it is analyzed. But, frequently, analysis is nonexistent. When your motor reliability is in question, there could be many reasons including safety issues, quality control, and storage. Motor experts Bethel and Wayne Pilliner, CMRP, The Mosaic Co., Plymouth, MN, say there are three keys to motor reliability:

Quality control. Spend time in the motor-repair shop monitoring the activity.

Trending. Collect data, take advantage of new technology, and remember that trending is your friend.

Troubleshooting. There is an end of life for everything. Get ahead of that. Have a casualty procedure and follow it. Alleviate time delays.

randmDuring the 24th Annual SMRP Conference, held Nov. 2016 in Jacksonville, FL, Bethel and Pilliner presented more tips on avoiding gaps in your motor-reliability program. The first question to ask, they advised, is “Where is your motor-maintenance program?”

Bethel emphasized that it is also important to develop a good business case. This is critical to get buy-in from management for equipment-improvement initiatives, he said.

More questions to answer

• What is the problem?

• What is the gap?

• What is the financial impact?

• What are the goals and objectives?

• What are the roles and responsibilities of the motor-maintenance team? Ensure that these are clearly defined.

• What is the return on investment? Make calculations and predictions for an expanded time period.

The strategy is also something that should be clearly defined. Consider these proven motor-maintenance-strategy process steps:

• Maintain an accurate list of the motors you have in stock and the ones you need to order.

• Identify the criticality of every motor.

• Determine motor-failure modes based on past history.

• Assign corrective actions to prevent established failure modes.

• Develop a sustainable program to ensure compliance.

• Set testing standards and tailor them for your site.

Bethel and Pilliner described several case studies in which this approach helped companies determine the gaps in their motor-reliability program. Look at the gaps as opportunities to learn and improve, they said. Once gaps are identified and a strategic plan is in place, motor reliability at your facility will improve.

Key tips

• Success is dependent on buy-in from stakeholders.

• Motor-testing compliance is greatly improved with M-tap installation, compliant with the 70E standard.

• Put a fundamental maintenance program in place to complement the motor-testing protocol.

• Ensure motor-testing technicians are trained in the technology.

• Knowing the condition of your motors enhances your workflow process. This can result in significant savings from an efficiency and cost-of-failure point of view.

“Productive and long-lasting operation of motors in today’s business environment is the reason for the development of advanced technology and site procedures to increase reliability and assure a quick return to productivity in the event of troubleshooting and repairs,” Bethel said. “The transition of data to usable information becomes more efficient when the analyst has help to make the right decisions.” MT

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