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222

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October 1, 2007
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Boosting Your Bottom Line: Optimizing Motor-Driven Systems Can Save Big

Your company can achieve signifi cant energy and bottom-line savings by implementing an effective motor management plan. With a welldefi ned, proactive plan in place, you are in position to optimize the benefi ts of NEMA Premium™ motors and best practice repair. But, the savings don’t stop there.

Examining and optimizing motors as part of an overall system can elevate benefi ts to the next level. Savvy facility managers realize that the savings and productivity gains that can be achieved by optimizing motor-driven systems can be greater than the combined savings of upgrading individual components.

Our July column highlighted the benefi ts of adjustable speed drives in appropriate applications. This was a fi rst step in looking at motors as part of a larger system. A logical next step might be to identify motor systems that are common to a variety of industrial processes and commercial applications, e.g. compressed air, pump and fan systems.

According to the Department of Energy (DOE), motor-driven systems account for 64% of the electricity consumed in the U.S. industrial sector. Furthermore, signifi cant reductions are possible through the use of proven equipment and technologies.

Compressed air systems, for example
Compressed air, a utility that is generated inhouse, serves a variety of applications. While a majority of industrial facilities have compressed air systems, few realize that compressed air generation accounts for a signifi cant portion of their facility’s energy consumption or that these systems can be notoriously ineffi cient—as low as 10-20%.

System optimization measures include identifying systems that are leaking or poorly confi gured for end use, and reducing system air pressure or running times. Both the Compressed Air Challenge Website and DOE’s BestPractices Website offer a wide array of resources to help facility managers understand and capture these benefi ts.

Optimization resources are available
The Department of Energy’s Website provides optimization resources for other motor-driven systems as well. These include sourcebooks, software tools, tip sheets, technical fact sheets, handbooks and even market assessments for the following areas: steam, process heating, motors, pumps and fans. The Environmental Protection Agency is yet another valuable resource. This agency’s Web site, www.energystar.gov/, provides information and tools to help facility managers who are interested in generating energy and cost savings. (Tune in next month to learn more about the EPA’s energy management strategies for achieving continuous improvement and its benchmarking tools for commercial and industrial facilities.) The Motor Decisions MatterSM Web site provides links to additional optimization resources and information about funding sources for energy effi ciency across the U.S. and Canada. Visit www.motorsmatter.org, and click on Helpful Resources. MT


The Motor Decisions Matter campaign is managed by the Consortium for Energy Efficiency, a North American nonprofi t organization that promotes energy-saving products, equipment and technologies. For further information about MDM, contact Ilene Mason at imason@cee1.org or (617) 589-3949, ext. 225.

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243

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October 1, 2007
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Real-World Learnin

1007_inputoutput1We’ve said it before: We are always interested in reader feedback, no matter how it reaches us. Letters sent directly to our contributors in response to their respective columns or features can be especially helpful in that they often allow us to draw conclusions on the state-of-the-art, the mood of the industry, etc. That, in turn, lets us better serve you, the reader. An example of this process can be seen in a round of communications between Heinz Bloch and an unnamed Plant Manager. Focusing on “learning” out in the real world (an important topic in both MAINTENANCE TECHNOLOGY and our sister publication, LUBRICATION MANAGEMENT & TECHNOLOGY), we probably could have used this thoughtful exchange as a springboard to a stand-alone article in either magazine. Instead, we’ve chosen to share parts of it here, along with some additional insight from Heinz…

Dear Heinz:
I have enjoyed and learned much from your articles over the past two years since I discovered them. I particularly enjoyed your recent articles with implied (yet justified) comments about management not acting on rotating equipment advice—it brought a smile to my face. In my first stint and first year as a Process Manager, I was guilty of trying to be too clever. However, I soon came to appreciate the value of a first-class rotating equipment engineer and his advice.

At this time, I am about to re-enter a Plant Manager role in a refinery and wish to buy a text covering rotating equipment. My earlier experience has taught me how critical machinery issues really are. I’m aware of the importance of understanding the advice I am being given; certainly, a manager needs to know enough to ask the right questions.

That said, I recall that in one of your articles you quoted several texts as essential and am wondering if you would mind advising which of two or three of your books would be best for me.

Please keep the articles coming. I am bringing them to the attention of my colleagues here to make us Chemical Engineers more knowledgeable about rotating equipment.

Name withheld by request
Via e-mail

Heinz promptly replied to the Plant Manager…
The (referenced) listing was actually published in the May-June 2006 issue of our sister publication, Lubrication Management & Technology (formerly Lubrication & Fluid Power). The first three books in our “Essential Machinery Reliability Library” should be of value and are recommended in answer to your request. However, the following three-step plan should be of general interest when training professional employees:

1. Technical book(s) should be read in stages and must be assimilated or digested in stages. A stage of development builds on the previous stage. As an example, issues of pump specification should be learned after having observed pump repairs.

2. The technical reader will have to understand when, where and how best-of-class actions or procedures described in the “Essential Reliability Library” (and representing Best Practices) differ from the way things are done at the reader’s facility.

3. Equipment Reliability Professionals have to justify to their management why one should use Best Practices and what would be the safety and reliability implications of deviating from Best Practices.

Heinz P. Bloch, P.E.

We can assume that the Plant Manager who penned the letter (and prompted the above response) realizes there is more to training than meets the eye. As so many of our contributors continue to point out in our pages, there is. Most importantly, there is no progress without training. Heinz elaborates…

Indeed, the frequent restructuring that took place and continues to go on in industry has affected the training of both professional and craft employees. In some locations, entire training departments have been dissolved and little or nothing has replaced them.

The challenge, though, is the implementation of meaningful and technically sound replacement training for those who accept the premise that people versed in stateof- the-art capacity assurance methods are a real asset. In response to this at some plants, a loosely defined and sporadically executed self-teaching routine has moved into the void. But, there is a better way.

The beginning of training should be a well-focused, written role statement that explains to both manager and managed their respective perceptions of the technical employee’s role. Is he or she a parts changer or innovator? A fixer or an improver? A person who is expected to react to problems or anticipate problems? The role statement must, at least, allude to a training plan. The technical person and his or her supervisor should discuss both role statement and training plan initially and, of course, during scheduled future performance reviews.

A detailed training plan should probably be a separate document. Such a plan will give firm guidance and yet leave lots of room for individual initiative. Its aim will be the achievement of proficiency in a technical skill or craft. As an example, here’s how technical training for a young engineer could be structured:

Let’s say your facility employs four maintenance or reliability engineers or senior reliability technicians. You could get them to engage in worthwhile self-training by obtaining subscriptions to trade journals like Maintenance Technology and Lubrication Management & Technology, among others. (As you may already know, these types of subscriptions often are provided at no cost to qualified subscribers based on job title and responsibilities.)

If you find value in having your own personal copy of a publication month after month, others around your operations probably will, too—particularly those who work in large organizations or who travel extensively. Many publishers would be happy to ensure that a reasonable number of additional copies find their way to key technical and management personnel at a company or site. (In the case of the publications referenced here, one of the easiest ways to do this is to encourage your associates to qualify for their own subscriptions by filling out the required forms on www.MT-online.com and/or www.LMTinfo.com. Keep in mind that these periodicals are sent to qualified subscribers in the U.S. and Canada free of charge.)

All technical personnel should have access to the information in the publications that are deemed to be important to your operations. The name of each technical person should be at the top of the in-plant routing sheet of two or three of these periodicals and he/she would be required to screen the content of the periodical(s) for relevant material. The employee would not have to read the various articles, but would be expected to recognize from headings or abstracts the present or possible future usefulness of the write-up. Electronic copies would have to be made of these writeups and sent to the other “Professionals-in-Training” on the “PIT” distribution form. One copy would be filed in the plant’s central computer under appropriate headings that might follow a simple, but logical identifier system to enable easy retrieval via a straightforward, well crossreferenced PC-based software program. Remember, before making copies and distributing copyrighted articles, it is a matter of professional courtesy to contact the editor to request permission to do so.

The second phase of training might be called the “dig-upthe- facts” phase. Each “PIT” would be asked to present periodically scheduled briefings or information sharing sessions to mechanical workforce personnel assigned to shop or field (e.g. millwright) tasks. Tacked on to the ubiquitous safety meetings, these 7-10 minute briefings or information sharing sessions might deal with topics such as:

  • How to Install Rolling Element Bearings in Our Large Mixers
  • Proper Lubrication Procedures for Our Pumps and Motors
  • Why Four Different Types of Couplings Are Used at Our Plant
  • When to Use Bellows Seals Instead of Pusher Seals in Our Plant’s XYZ Process Unit

There are literally hundreds of worthwhile topics to research and discuss and disseminate. The process would compel the presenter to do some homework instead of guesswork, communicating with vendors and manufacturers instead of reinventing the wheel, and perhaps even rediscovering one or more of the many good technical textbooks which are generally available at a fraction of the cost of making a single mistake. The researcher also would be educating himself/ herself and contributing to the development of team spirit and the enhancement of mutual respect and cooperation among the many job functions in the plant.

From here, the phased approach to training could move to in-plant courses by competent presenters with both analytical and practical knowledge in machinery maintenance and reliability improvement procedures, and then progress to welldefined, known-to-be-relevant outside seminars or symposia. If someone in your company or at your site suggests that training is expensive, just let them try to calculate what your costs would be without proper training.

Which takes us back to the original reader’s request for an updated list of books that we have most often consulted in the past 25 years… For the “Essential Machinery Reliability Library” list, e-mail jalexander@atpnetwork.com. Be sure to put “Requesting Essential Library” in your subject line. On the other hand, you also can compile your own list through a Google Search or by entering Amazon.com and looking for either the author’s name or the approximate title. The terms “RELIABILITY” or “UPTIME EXTENSION” usually appear in any such search.

E-mail questions or comments to: jalexander@atpnetwork.com Or post them on: www.mt-online.com We reserve the right to edit letters for clarity and brevity.

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232

6:00 am
October 1, 2007
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Going for the gold…Part II

In the first installment of this series, the author discussed overcoming some common misconceptions to help you on your way to becoming an Elegant Maintenance Manager. This month, he deals with bringing corrective maintenance under control and extending it to preventive maintenance work to achieve efficiencies consistent with the assigned budget.

If one could get the right mix of preventive maintenance (PM) and corrective maintenance (CM), things might not be so bad. If CM could be reduced to zero, that would be grand, but that is not going to happen. Amid the propositions of RCM, TPM, RCA, the Pareto rule, best laid plans, etc., one still must contend with randomness. When our programs result in high levels of performance, the limiting factor is often randomness. Using the concept of randomness in analyzing equipment failure events is helpful in establishing the realistic limiting factors in PM and CM program development and management.

Small changes, big results
Before getting enthused about understanding the technical milieu of equipment failure modes and causes, failure intervals and maintenance task development in recovering a dysfunctional maintenance program, first look for an opportunity of a large reward for a small resource expenditure. One large reward, for example, could be a 50% reduction in corrective maintenance resulting from a program developed and implemented in-house (small resource expenditure). That 50% number is not unrealistic. A high incidence of maintenance induced failures in the CM arena result from poorly designed and implemented management strategy and systems. These “activity control failures” are commonly referred to as “personnel errors, miscellaneous, or unknown cause.”

If managers are not providing the maintenance staff with sufficient training, procedures, resources, time, leadership and competent supervision, they are their own worst enemy. One of the first and biggest values in maintenance program development is ensuring that you have a competent staff and that your management systems are effective. Only then can one proceed to implement a maintenance strategy in such a way that the maintenance staff does much more good than harm. Table I summarizes the analyses of hundreds of events at a variety of industrial facilities.

In addition to the categories shown in Table I, modification work (such as replacement of obsolete equipment, increasing capacity of an existing system, or meeting new regulatory requirements) can also be a significant cause of failures. In such instances engineering work is unavoidable, but sufficient engineering resources are often unavailable to complete all the requirements of installation, operation and performance qualification. In these cases the maintenance department is left with a classic, serious maintenance management problem, because the complexity of these seemingly simple facility events is not recognized. These failures are also “activity control failures,” even though most people think they are making desired improvements.

Let’s see if there is an elegant approach to addressing these serious problem areas in a maintenance program that is in a hole. Is there an elegant way for maintenance managers to stop digging, and then develop a strategy to lift their organization out of the hole they find themselves in?

Stop digging, start climbing
First, develop a “maintenance process” for doing your maintenance business. The maintenance process describes the conduct of maintenance at your facility. It becomes one of the key components of your strategy. It tells your staff how you want them to conduct the business of your department. Administrative aspects of the process probably already exist simply because of government regulations for doing business in general. The Elegant Maintenance Manager now must add the technical aspects and describe how the average maintenance technician and his supervisor should be conducting maintenance business and ensuring the operability and reliability of systems and equipment.

For example, does the maintenance technician know where to find the source documents for working on equipment? Are there source documents? How does he know what post-maintenance testing to conduct and what the acceptance criteria are? How does the supervisor interact to ensure communication and implementation of the maintenance process?

In a later article we will see that the maintenance process is a critical training document. That’s because if the maintenance manager specifies the conduct of maintenance, there will be goals and objectives for the maintenance technicians and supervisors to achieve on a consistent basis. If this is not done, work orders can become adventures being directed by a loose cannon or two. Maintenance process knowledge is as important as technical skills—do your people know how to work?

Second, take a look at your CM work load. Based on failure cause determination in hundreds of analyses covering thousands of mechanical, electrical, and instrumentation and control components, I discovered eight causes of failure for use in front end development of maintenance programs. These causes are:

  • Vibration
  • Degradation
  • Corrosion
  • Wear
  • Maintenance activity
  • Environment
  • Installation anomalies
  • Operations and testing

Coupled with the foregoing focus on irregular failure causes, this also is a great opportunity to apply the thinking inherent in RCM to address the CM problem.

Choose specific maintenance tasks on the basis of the actual failure characteristics for the equipment under study as evidenced by the CM history. All these tasks can be described in terms of the four basic forms of maintenance tasks, each of which is applicable under a unique set of circumstances. The four forms of maintenance tasks are well defined in the RCM literature.

Earlier, we discussed the problems associated with things like obsolescence and modifications that are not maintenance problems but become defacto maintenance problems due to a lack of an engineering function. Applied RCM thinking will help Elegant Maintenance Managers identify this trap before it gets sprung on them. Getting CM under control this way is cleverly apt and simple and obvious. Even in RCM program applications, this approach works when the specified RCM task doesn’t meet expectations for whatever reason, and CM is occurring on an “RCM’ed” unit.

There is even a concept in RCM that goes something like this for overhaul tasks: In the case of overhaul tasks, the question of applicability as well as effectiveness requires an analysis of operating data. Unless the age-reliability characteristics of the item are known from prior experience with a similar item exposed to a similar operating environment, the assumption in an initial program is that an item will not benefit from scheduled overhaul. The implication of these concepts is “make good use of CM data in specifying applicable and effective tasks.”

Let’s see where we are at this time after completing the previous actions. We stopped digging the hole we were in by managing. That produced the strategy that materialized in a maintenance process statement that the maintenance supervisors communicated to the work force, then implemented in the field as the staff conducted the business of maintenance. If supervisors cannot be counted on to communicate the strategy and see to implementation, then coaching and counseling are in order followed by getting competent supervisors in place if the incumbents cannot adapt to change. The reactive component of the maintenance business came under control with the conversion of CM work to PM work. That’s a good start on being effective. By managing, one attacks 50% of the CM cause, and by applying RCM thinking, one can attack just about all the remaining CM problem(s).

In the opening paragraph, randomness was put forth as a limiting factor in the maintenance business. This is where randomness comes in to help the maintenance manager understand what the PM/CM ratios are expected to be. Empirical determination shows that the reasonable values of the PM/CM ratios (computed as PM work orders divided by PM+CM work orders) are approximately as follows:

  • Mechanical Systems—80%. Due to physically harsh service environments and the interplay of many uncontrolled variables, there is a significant impact from random events in these systems. These systems also generally are associated with energy transport and conversion through physical system interaction.
  • Electrical Systems—90%. These systems are generally better controlled regarding environmental conditions, thus minimizing uncontrolled variables and random events. Also, the energy transport and conversion is in many cases by means of an electromagnetic wave, thus taking less of a physical toll on equipment.
  • Measurement and Control Systems—>90%. High CM in these systems is generally due to poor heat management or poor design. These systems should be among the easiest to maintain through a PM program and have a minimum impact from random events.
  • Overall—85%. This overall performance level accounts for about a 15% random failure level that will show up as the CM workload in effective PM programs.

Within a year of instituting the management and CM changes, the Elegant Maintenance Manager should be able to achieve the PM/CM ratios listed in this bulleted list.

Save some, get more resource efficiency
Now would be a good time to take an initial shot at bringing efficiency into the PM program. It is important to be effective first, then efficient, so that’s where the Elegant Maintenance Manager would be at this point in the maintenance program recovery. There are obvious savings from reducing the number of PMs, so the PM intervals should be examined to ensure the maintenance staff is not overdoing the PM thing.

1007_elegantmaint1Examining the PM results versus the interval of performance and effectiveness of the PM process is the first step in adjusting the PM schedule. For a start, consider the following:

  • Eliminate, within reason, all “tear down and inspect”-type PMs. This is the pointless “tear up the plants to check the roots” mindset that seems to make sense but in reality is one of the main causes of maintenanceinduced failures.
  • For scheduled replacement tasks, examine closely the item being replaced and make a determination as to condition. If it is not that bad, consider extending the PM interval by 50%. If you and your staff do not know how to make this judgment call, learn how to do this as soon as possible.
  • For all equipment in low-energy or low-duty-cycle applications, consider doubling the PM interval. Examples of low-energy parameters include temperatures less than 300 F, flow rates less than 100 gpm, operating pressures less than about 100 psi air or water or low-pressure steam systems, and duty cycles of eight hours per day or less.
  • For all changes made per the recommendations listed here, revisit the interval question at the next performance of the PM to again extend the PM interval as possible.
  • For non-critical, low-cost components with no collateral damage potential, consider a run-to-failure maintenance strategy and eliminate the unit from the PM program except for routine monitoring for deficiency identification.
  • Evaluate all skid-mounted instrumentation and control components for usefulness compared to remote process monitoring instrumentation and control systems. Remove redundant or not-used devices from the PM and calibration programs.
  • Design special tools, jigs, and fixtures to support maintenance on certain equipment as necessary and place these items under inventory control to ensure availability when needed.
  • Consolidate PMs. Ensure that subinterval PMs are embedded in longer interval PMs and that as many PMs as possible are included in work packages to minimize equipment downtime and minimize PM logistics.
  • Supply each supervisor, as practical, with a set of specialty tools and measuring and test equipment for their controlled use on their shifts.
  • Remove all barriers in the procurement process from the requisition phase to the receipt and staging of parts to support PMs. This will likely require some “just in time” (JIT) procurement tactics, vendor partnering, and removal of enterprise asset management system (EAMS)-type roadblocks.

Two elegant programs to implement
There are two must-have programs that will provide some of the important information details for the maintenance information flow network. These details are important inputs to the feedback networks that the maintenance department needs to ensure awareness of what is going on. These programs are the “CM Backlog Measure Program” and the “Material Condition Inspection Program.”

A CM work order is generally designed to process work within the constraints imposed by the facility organizational structure. The constraints are in the form of assigned responsibilities and authorizations for completing the specified tasks including appropriate paperwork closeout. If this system is run efficiently and adequate staff is available, experience has shown that an optimal CM backlog can be defined such that there are sufficient manpower resources to address other tasks besides CM or handle a reasonable, sudden increase in the CM workload.

What does this really mean and what does it have to do with a maintenance department’s backlog measure? It means that backlog is something that occurs due to a maintenance organization’s ability to respond to an increased workload in such a fashion that the increased workload is still manageable as part of the organization’s day-to-day business activities. The essence of this concept is that the organization should have the inherent characteristic of a system that responds to how much work there is to do.

Historically, CM backlog has been presented as a trended plot of total backlogged man-hours or total open work requests. While this type of measure does provide some useful information on the CM backlog, it does not tell much about the effectiveness of the organization or why the backlog exists as it is. This is really what we would like to know as opposed to knowing how much CM work has not been done. We are more interested in what caused the alarm than the alarm itself. In order to make use of a CM backlog measure consider this measure to be an indicator of how time-dependent work is addressed by the maintenance organization’s work order processing system. The key item for understanding what backlog really means is the phrase “time dependent.”

The material condition of the facility should be maintained to support safe and reliable operations. It should be everyone’s business to identify and correct deficiencies and prevent the deficiency culture that comes from complacency. The basic approach to developing the facility material condition inspection program (MCIP) is as follows:

  1. Develop and implement an inspection program to define responsibilities for conducting inspection, identifying and correcting deficiencies, and assuring cleanliness, safety and good material condition. Establish inspection areas so that the entire facility is inspected, including areas with difficult access.
  2. Establish inspection guidelines and criteria to assist inspectors in performing their inspections.
  3. Develop a training program for appropriate station personnel, including operations personnel, facility managers, and facility supervisors, to receive inspection techniques training.
  4. Establish a means to report, track, and correct, identified deficiencies in a timely manner. Document each deficiency on a work order. (See Fig. 1 for a simple reporting document that is extremely effective for use by anyone.)
  5. Include recommendation of operation and maintenance good practices in this reporting program as a means of identifying areas for improvement.

A significant side benefit of this program is the equipment monitoring and diagnostic results of these inspections—a sort of informal predictive maintenance. But this predictive maintenance program is a real bargain, since the cost is simply the cost of using available resources.

Conclusion
This installment of the Elegant Maintenance Management series deals with the fundamental mission of the maintenance department. We all know that a lot of CM comes from poor judgment, and that good judgment comes from the experience of bringing a lot of CM under control. Next, that control must be maintained and extended to PM work to achieve efficiencies consistent with the assigned budget. Only then can there be sufficient success to ask for more resources. Remember, only you as the maintenance manager can stop digging. Empower your talented staff to do the climbing.

Dr. Huzdovich is the service contract manager for Raven Services Corporation at the Bureau of Engraving and Printing’s Western Currency Facility in Ft. Worth, TX. He directs the O&M and engineering work performed by the Raven staff of 58 employees, which is responsible for the 24/7 operation and maintenance of all stationary and production support equipment in these operations, including their 850-ton chilled water units, 800-hp low-pressure steam boilers, 3600 KW of diesel generator capacity, the environmental management system and currency mutilation destruction equipment. He also is the principal engineer and consultant providing maintenance and reliability services and expert witness services for Forensic Action Services, LLC, in Denton, TX. Huzdovich serves as an adjunct instructor with the University of North Texas, MBA Program. E-mail: jhuzdovich@verizon.net; telephone: (817) 847-3674.

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210

6:00 am
October 1, 2007
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Inexpensive Electrical System Insurance

Surge protection devices…

The concepts are simple, the solutions straightforward. You’ll find it much less expensive to keep surges and electrical noise from frying your equipment and processes than to recover from the aftereffects of such events.

When it comes to losses from electrical and electronic equipment failure and disruption, few events can match the destruction caused by surges (transients) and electrical noise. These phenomena are responsible for between 30% and 50% of most electronic equipment field failures today—and that doesn’t even begin to take into account the latent damage or degradation to electrical equipment such events cause. Moreover, although no firm figures have been established, the estimated amount of dollars in lost production and lost revenues associated with these problems is staggering. A company can greatly reduce its risk of equipment damage, component degradation and system disruptions with a robust surge protection system.

Understanding the issue
To get a real handle on the problems associated with surge and electrical noise, it’s important to fully understand a number of key concepts.

  • Concept #1: Surges can be generated external to a facility in the form of lightning, as well as originate with a utility system. While these typically are the first sources that come to mind, numerous studies have shown that they account for only 20% of all electrical surges. The remaining 80% can be accounted for by culprits within a facility.
  • Concept #2: Most electrical surges are generated within a system, with common culprits being switched mode power supplies (SMPS), fax machines, printers, welding machines, cycling operation of motors and electronic ballasts for fluorescent lighting, to name but a few.
  • Concept #3: Many of the same culprits also are the source of electrical noise.

Early on in the development of surge protection, the industry was guided by the idea that a certain voltage threshold had to be reached before a surge caused any real damage. We now relate to this idea via terms such as “clamping voltage” and “let thru voltage.” Transients with voltages less than the clamping voltage were thought to be of little significance.

The problem is that sensitive electronics in our datacentric world are more susceptible to transients and noise that don’t reach the clamping voltage and now go undetected more than at any other time in our modern economy. The cumulative effect of these transients that are not diverted or absorbed is negative. For starters, the quantities of surges that are below “clamping voltage” threshold are more numerous than the surges that are “clamped” by the surge protection device. Not only do these smaller surges contribute to degradation of equipment components such as capacitor dielectric, they also can cause errors if coupled into the communications signal where they can mimic the intended signal’s faster operating speeds and lower operating voltages. This coupling becomes easier since circuit board wiring traces are forced to become smaller and, thus, less of a barrier to prevent degradation. This leads us to a fourth important concept that needs to be understood:

  • Concept #4: Transients of significantly less voltage levels than previously considered detrimental are now more likely to be the source of many problems.

Many facility owners and managers believe that since they have never had anything burn up, they don’t have any problems. This is only partially true as total destruction of equipment is only one of the 3-Ds of Surge and Electrical Noise Damage, which also includes degradation of components and process disruption.

  • Concept #5: The fifth concept is that all damage done by surges and electrical noise is not totally destructive, but could be any one of the 3-Ds—destructive, degradation or disruptive.

The surge and electrical noise issues outlined in these five concepts may appear to be overwhelming at first. However, by taking a scientific approach using industry codes, standards and guidelines, an engineered solution is within economic reach. As a starting point, let’s look at the basic function of a surge protection device (SPD) and how it is applied.

SPD basics
The backbone of every SPD is the metal oxide varistor (MOV). The MOV is a nonlinear device that has very high impedance when not activated with an accompanying leakage current typically in micro-amps. It is seen as a short circuit when the voltage between conductors exceeds the “breakdown voltage.”

Internally, the MOV has a myriad of diode-like junctions that shunt surge current through it when biasing voltage thresholds are achieved. The diode-like junctions are made of zinc oxide (which sometime contains small amounts of other metal oxides such as bismuth, cobalt and manganese). It provides bidirectional clamping of surges that must quickly dissipate surge energy as heat while shunting the transient to ground. The MOV typically has an intrinsic response time in the range of 500 picoseconds, which makes it great for events that are in microseconds. The voltage capacity of a MOV is primarily determined by the thickness of the disc while the current-carrying capacity is primarily determined by the surface area of the disc.

Many SPD/TVSS manufacturers stack MOVs in parallel and series to achieve higher performance levels. An important concept about the MOV/SPD is that it is a sacrificial device with degradation of performance over time with exposure to surge energy. It is considered to be at the end of its life when it has lost 10% of its design capacity. Many manufacturers combine the transient suppression capabilities of the SPD with filters tuned to block electrical noise.

SPD application standards
The first standard to consult regarding SPD application is the National Electrical Code (NEC®), NFPA-70, Article 285, which provides details on the installation of such a device (also called a Transient Voltage Surge Suppressor or TVSS).

Grounding and bonding…
Just as important, NEC, Article 250, grounding is a paramount concern in surge protection. Most SPDs on the market today divert surge energy to the facility grounding system. Therefore, the importance of a low-impedance bonding and grounding system for the facility can’t be overstated. Anything less than a low grounding and bonding impedance will cause surge energy to be diverted throughout the facility, with potentially negative effects.

For example:

  • The facility staff could be subjected to dangerous voltages during the event.
  • A large percentage of microprocessor-based equipment uses the ground as a logical reference point. Surge energy diverted to the ground would pollute this reference point.
  • Voltage differentials could be created causing inter-grounding system potential differences and undesirable currents on the grounding network.

Three key points must be addressed regarding grounding and bonding:

  • First, it is imperative to have a qualified person evaluate the facility’s grounding and bonding network for NEC compliance. All outlets should be checked for proper polarity and an equipment ground conductor impedance that should be less than 1 ohm.
  • Second, it is mandatory to determine if the grounding system is robust enough to optimize the function of the SPD (i.e., proper wire size, tightness of connections, etc.).
  • Third, it is essential to determine specific corrective action required to bring the grounding network to both NEC compliance and to the level of performance to address transients and electrical noise.

Zones of protection…
After NEC, the next standard to consult is the IEEE 1100 – IEEE Recommended Practice for Powering and Grounding Sensitive Electronic Equipment (commonly called the Emerald Book). One of the primary recommendations put forth in this guide is the implementation of Zones of Protection. Three zones or levels of SPD deployment within a facility are identified along with corresponding device categories.

  • The first zone is at the service entrance where the most robust SPD is placed to divert surges coming from external sources such as lightning. SPDs installed here are listed as Category “C” devices.
  • The second zone of protection is within the facility at locations identified as susceptible to surges, as well as generators of surges. SPDs at these locations are listed as Category “B” devices and are installed on equipment such as switchgear, switchboards, panel-boards and branch circuit panels. The SPDs installed in this zone further reduce surge energy and divert it to ground, thereby limiting the surge voltage to a level that is tolerable to the equipment requiring protection.
  • The third zone of protection is at the outlet. SPDs installed here are listed as Category “A” devices. Coordination of SPDs is required for optimum protection.

In general the closer the “Clamping Voltages” are to operating voltage, the better the protection. For comprehensive protection within the facility, SPDs should be installed to prevent transient propagation from source generators as well as to protect sensitive loads.

Additional standards…
Other standards that are useful in evaluating SPDs include, but are not limited to:

  • UL 1449 2nd edition (latest edition 2.5, revision effective 7-February-2007) is the safety standard for all equipment installed on the load side of the AC electrical service (480 V and below), as well as throughout the facility including the plug in outlet TVSS.
  • NEMA-LS1 is the primary specification guide for low voltage (< 1000 V) AC power SPD applications.
  • ANSI/IEEE C62.41 describes typical surge environments and includes standardized waveforms for testing of protective devices.
  • NFPA 780 is the standard for Lightning Protection Systems.

Beyond the standards, many SPD manufacturers provide general information on their respective Web sites. Finally, the NEMA Surge Protection Institute (www.nemasurge. com) offers a vendor-neutral (i.e. “unbiased”) SPD presentation.

Your next step
The next logical step is to evaluate the surge risks at your facility. This includes identifying external surge sources and the equipment within the facility that is susceptible to surges and noise, as well as the likely generators of surges and electrical noise within the facility.

A good design segregates the electrical power feeds of susceptible equipment from power feeds of surge and noise generators. Where possible, this segregation ideally should be at the service entrance. Outfit each panel you’ve identified as having susceptible loads or surge and noise generators with a properly sized SPD to mitigate surges.

When you are selecting an SPD, you have many features to consider. These include remote annunciation capabilities, audio alarms, local indicator lights, etc. The most essential function, though, is the SPD’s ability to divert transients. It is important for your chosen device to have a diagnostic indicator (visual, audible or otherwise) to verify that it is still functioning and hasn’t been disabled from the last surge suppression event it experienced. Therefore, some type of indication—either local indicating lights or remote annunciation—is critical. Noise filtering also is crucial, given the growing presence of electrical noise contamination. Several manufacturers claim to have sine wave tracking that allows their SPDs to pick up surges and noise on a frequency basis versus voltage thresholds. Another often-touted feature is a surge counter. Keep in mind, however, that a surge counter is only an indication of past performance—it’s neither an indication of future performance nor a gauge of existing lifetime of the device.

SPD installation
SPDs are either installed in equipment at the factory or installed after the equipment has been shipped and installed on site. There are three advantages to factory installation: a higher probability that the SPD lead lengths are short and as straight as possible; the connections to the buss will be as tight possible; and there is a uniform equipment appearance.

Most major equipment manufacturers provide optional SPD installation with their gear. In many instances, these devices are added after the installation of the major equipment.

When an SPD is installed after major equipment has been set and in operation, it typically is done external to the equipment. The installation practices of external SPDs are critical in order to achieve proper surge protections. It is recommended that external SPDs be installed as close as possible to the electrical buss being protected. Electrical connections must be tight, while connection wiring should be as straight as possible and as short as possible. The effect of excessively long connection cabling is to raise the “let thru voltage” threshold. So use the guide phrase “Close, Tight, Short & Straight” when it comes to external SPD installation and cabling: Close to the electrical buss being protected, Tight connections, Short & Straight lead lengths.

Summary
Once awareness of the problems associated with surges and electrical noise has been achieved, the next step is to identify where the areas of risk exist within the facility and what type of protection is required at each. Selection of an SPD that adequately diverts and filters the transients and electrical noise away from the equipment then follows.

For optimal device performance, installation of each SPD must adhere to strict guidelines. To that end, don’t forget that the facility grounding system must be inspected and upgraded, where necessary. Poor grounding can provide paths of least resistance that divert transients and electrical noise to critical systems instead of away from them.

Many resources are available to help with the needs assessment, evaluation, design, product selection and installation of SPDs. In general:

  • Verify that the protection scheme complies with IEEE recommendations and is installed according to both NEC requirements and the manufacturer’s guidelines.
  • Confirm that zones of protection are coordinated providing maximum surge attenuation and noise contamination filtration.

The threat of damage to electrical and electronic equipment from transients and electrical noise is real and growing. Our data-centric world is more susceptible than ever to damage from transients and noise, be it total destruction, degradation of equipment components or system disruption and malfunction. Since microprocessor-based equipment functions with faster operating speeds and lower operating voltage than other equipment, surges and electrical noise previously classified as non-threatening are significantly more damaging.

Although surges and electrical noise can’t be totally eliminated, they can be mitigated through an engineered approach, thereby reducing their damaging effect. This leads to greater reliability and overall improved productivity. In this regard, surge protection really is an inexpensive form of electrical system insurance. MT


John Gray is manager of the Guarantee Electrical Construction Company’s Critical Power Group, based in St. Louis, MO. The group’s primary focus is on overall electrical power reliability for its clients. Services include electrical system testing, troubleshooting, analysis, mitigation and validation. 

Defining The Problem

What is a surge?
“A sub-cycle disturbance in the AC waveform that is evidenced by a sharp, brief discontinuity of the waveform. May be of either polarity and may be additive to, or subtractive from, nominal waveform.” …Emerald Book

What is electrical noise?
“Unwanted electrical signals that produce undesirable effects…” …Emerald Book

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Capacity Assurance Market

1007_ir_cameraIR Camera With Real-Time 14-bit Digital Recording         Based on a high performance 320×240 detector array, Electrophysics’ TVS-200EX infrared camera produces very high quality thermal images. Advanced features include in-camera real-time 14-bit digital recording, image fusion of thermal and visible images as well as temperature alarm functions. Wide angle and telephoto lenses are available as accessories. The camera is compact, IP-54 rated and lightweight and features an articulating high brightness LCD display. Standard calibration is to 500 C with optional calibration to 2000 C. Users can visualize images in IR only or fuse IR and visible together to produce images that are easy to interpret.

Electrophysics Corp.
Fairfield, NJ

More Efficient Heat Transfer

According to ITT Standard, its Plateflow plate and frame heat exchangers yield heat transfer coefficients three to five times greater than other exchangers, and only require one-third to one-fifth the surface area of conventional shell and tube exchangers. The units are available in Free Flow, Double-Wall and Semi-Welded plate designs. They can also be specified in 35 different models with connections up to 20” in diameter.

ITT Standard
Buffalo, NY

Monitoring Turbomachinery

DEmerson Process Management has extended its PlantWeb® Smart Machinery Health Monitoring capabilities to include turbomachinery protection per API 670. The company’s new CSI 6000 Machinery Health Monitor integrates with the process automation environment to help maximize equipment reliability and plant performance. According to the manufacturer, it protects critical machinery from catastrophic failures and permits orderly shutdown of equipment and related processes.

Emerson Process Management
Austin, TX

1007_catalogComprehensive Fan & Blower Catalog

Cincinnati Fan has released its new general products catalog, #fl-0607. The full-color document includes the company’s complete product line of fans and blowers for exhausting, pressurizing, cooling, drying, air quality control and general air movement. The majority of the product line featured can be shipped within 10- 15 working days, and a RUSH program allows for many products to be shipped within 5 days.

Cincinnati Fan
Mason, OH

1007_shaftInnovative Shaft Locking Solutions

Torque Transmissions has introduced several solutions to help decrease vibration and inertia as machine speeds increase and indexing requirements becomes more precise. The company’s shaft locking options for its high-performance gears and pulleys include keyways, set screws, dbores, proprietary shaft locking mechanisms and collars. According to the company, these new options can reduce product costs through reduced downtime, equipment repairs and product loss.

Torque Transmission
Fairport Harbor, OH

1007_pumpsUS NAVY Shock Qualified Structural Composite Pumps

Sims Pump Valve Company’s SIMS Series 10000, Shock Qualified Navy Pumps incorporate pumps and baseplates made of Simsite Patented Structural Graphite Composite materials. According to the manufacturer, these materials offer excellent mechanical and physical properties, wear characteristics, and unsurpassed corrosion resistance. The company also notes that unlike equipment incorporating metallic components Simsite® pumps and pump parts will not corrode or deteriorate in harsh salt-water environments. Combined with Sims’ “heavy duty” marine service, shock qualified, sealed bearing motors, the SIMS Series 10000 pumping system is capable of providing years of maintenance- free service.

Sims Pump Valve Company
Hoboken, NJ

1007_sensor1Secondary Reference Temperature Sensors

Hart Scientific, a division of Fluke, has introduced the Model 5609 Secondary Reference Temperature Sensor. Part of a line of high-temperature platinum resistance thermometers, the 100-ohm sensor has a temperature range of –200 C to 670 C, with short-term repeatability and long-term drift of ± 0.01 C at 0 C, as well as a typical response time of 12 seconds. The 5609 can be ordered in quarter-inch diameters, with sheath lengths of 12”, 15” or 20”.

Hart Scientific
Fluke Corporation
American Fork, UT

Portable FT-IR Spectrometers

1007_spectrometer1A2 Technologies has rolled out its new Mobility Series of Fourier Transform Infrared (FT-IR) spectrometers. Consisting of three systems, the MLp (shown), the ML and the MLx, these rugged products have been designed to be operated with little to no training by the user. According to the manufacturer, their durability and simplicity make them ideal real-time tools for lubrication condition monitoring and a variety of petrochemical, food and mining applications. Delivering accurate and precise information from even the most remote places on the planet, they help alleviate sample throughput problems and minimze bottlenecks.

A2 Technologies
Danbury, CT

 

Expanded APM Software Solution

Meridium Inc. has announced the release of its newest asset performance management solution, Operator Rounds. The new product extends the power of Meridium onto a handheld device allowing operations and inspection data to be captured in the field. Through automated alerting, operators can receive real-time instructions for what to do and how to react to the situations. Recommendations also can be created to initiate work. All data captured on the mobile device can later be synchronized with Meridium.

Meridium Inc.
Roanoke, VA

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The 7 Highly Effective Steps Of Remanufacturing

Undecided on the path to take? Here’s how the choice to remanufacture is helping end users across industry increase Mean Time Between Failures.

As more and more manufacturers turn to automation to improve their productivity and profitability, asset management becomes an even bigger part of the overall picture. Deciding whether to repair, remanufacture or replace equipment is a big part of that picture. As a result, Mean Time Between Failure (MTBF) has become an important measurement for determining which path to take.

Contrary to what some may believe, MTBF only represents a unit’s reliability (expected time frame between two consecutive failures), expressed in terms of hours—it is not synonymous with a unit’s service life. Surprisingly, there is no established industry standard when it comes to measuring MTBF. Therefore, many manufacturers have different ways for calculating it, mostly because the definition of a “failure” also can vary from company to company. In some cases, short periods of downtime (one hour or less) are not counted as a failure, even though frequent, minor interruptions usually point to a more serious performance issue.

The higher an MTBF rating, the more reliable the equipment will be, and, in turn, the greater its availability. Both MTBF and Mean Time To Repair (MTTR) are used to calculate a unit’s availability (expressed as a percent), as in the following equation:

1007_7steps_1

Some companies don’t measure MTBF at all. One reason may be that those manufacturers operate primarily in a reactive maintenance mode and measuring reliability is not a priority—reducing failures is. Reliability and failure reduction, however, are not mutually exclusive.

So, just how do you increase your MTBF and overall equipment availability? Consider the benefits of remanufacturing.

Remanufacturing vs. repair
Today, doing more with less has become the rule instead of the exception. Reduction in staff and spare parts inventory can lead to longer downtimes, reduced productivity and lost revenue. Consequently, manufacturers must find reliable resources to help keep their production equipment operating to specifications while increasing MTBF.

THE 7 HIGHLY EFFECTIVE STEPS OF REMANUFACTURING

Rockwell Automation’s seven-step remanufacturing process ensures that quality is built-in at every step.

1. Receipt and Verification of Unit for warranty; a bar code is assigned for easy tracking of repair history and order status.

2. Revisions and Enhancement performed to properly clean and update equipment to latest applicable hardware and copyrighted firmware.

3. Component Verification/Replacement of suspected faulty components.

4. Dynamic Functional Testing against current OEM specifications. Specialists determine operational status using dedicated test equipment including parametric testing.

5. Environmental Testing to highlight intermittent problems not readily apparent, which helps prevent premature failures.

6. Final Quality Inspection is performed by Quality Control Inspectors to ensure compliance to Rockwell Automation standards.

7. Securely Shipped in custom-engineered, anti-static bags and containers to help protect the remanufactured unit against static discharge.

When a failure occurs, many maintenance personnel are in the habit of sending the failed unit to a known thirdparty repair vendor without much thought being given to the process the vendor follows. Many times, these types of repair services are not only costly, they tend to focus solely on the part of the equipment thought to be the source of the problem—as opposed to focusing on the entire unit.

Remanufacturing goes beyond repair to offer a proactive, cost-effective approach to reducing equipment failures. It restores failed equipment to “like new” or better condition by providing firmware updates that can enhance product functionality and insure compatibility with future systems. Additionally, remanufacturing uses original (sometimes proprietary) components that maximize MTBF. Remanufacturers test to the original design parameters, which is a key component in certifying that the entire unit will function to specification. Testing outside of these parameters may compromise MTBF. The result: the remanufacturing process increases MTBF, reduces unplanned downtime and lowers overall asset costs.

For many types of equipment, true remanufacturing can be provided only by the original product manufacturer. That’s because only the manufacturer possesses the propriety knowledge, documentation, parts, revision updates and custom testing equipment to perform these services. Thus, many third-party repair companies are unable to test to the original design parameters. Moreover, the use of non-OEM parts can be quite problematic in some cases. Remanufacturing improves Overall Equipment Effectiveness (OEE), extends equipment or system life expectancy and allows for future integration with newer, more sophisticated automation products and technology.

Remanufacturing also helps to stabilize budgets by reducing the amount of repairs required each year, and provides the performance capabilities of new equipment at up to half of the cost.

As a leading manufacturer of automation and control equipment, Rockwell Automation offers valuable remanufacturing services and is the only authorized remanufacturer of Allen-Bradley products and Reliance Electric drives. Many remanufacturers have a proprietary remanufacturing process. For example, Rockwell Automation follows a seven-step process (see Sidebar) to ensure that every remanufactured unit operates to specifications, ensuring increased MTBF. Plus, data collected during this process is continuously analyzed to improve the design and remanufacturing product specifications.

Unlike traditional repairs, Rockwell’s remanufacturing service also includes a 12-month warranty on the entire unit, not just the replaced components. Expedited delivery and longer warranty terms are available through advance remanufacturing and advance exchange services. Fig. 1 illustrates the benefits of remanufacturing versus repair.

1007_7steps_fig1Quality built-in at every step
As previously noted, many remaufacturers follow a specific remanufacturing process, such as Rockwell Automation’s proprietary seven step process. At Rockwell Automation manufacturing facilities, units are examined thoroughly by highly trained specialists to find the true source of the failure. After the unit has been received, the warranty is verified and a bar code is assigned for easy tracking of repair history and order status. Next, the unit is properly cleaned and updated to the latest applicable hardware and copyrighted firmware. Any damaged, faulty or outdated components—including printed circuit boards—are rebuilt, not repaired.

The unit then undergoes Dynamic Functional Testing against current OEM specifications. Specialists determine operational status using dedicated test equipment, including parametric testing. The unit also goes through environmental testing to highlight intermittent problems that are not readily apparent, a process that helps prevent premature failures and increases the unit’s MTBF rate.

After the unit has been thoroughly cleaned, inspected, remanufactured and tested, Quality Control Inspectors perform a final quality check to ensure compliance with Rockwell standards. Finally, the unit is securely wrapped in a custom-engineered, anti-static bag and container to help protect it against static discharge during return shipment to the customer. Accessories such as keys, batteries and manuals also are included.

Making a smart choice
Companies should consider remanufacturing as a viable option for:

  1. resolving machine performance issues that decrease machine reliability and extend the duration of unplanned downtime;
  2. reducing and/or stabilizing machine repair costs; or
  3. accommodating process issues, such as machine reliability, production flexibility and operating to design specifications.

Your equipment vendor should have a vested interest in your success and be able to back its products with a broad array of support and maintenance services to help you minimize your operational costs and keep your competitive edge. This includes offering a comprehensive remanufacturing service that can restore equipment to a “like new” or better condition for much less than the cost of a new replacement item.

More importantly, though, remember that remanufacturing increases the Mean Time Between Failure, which reduces costs (unit does not need to be repaired as often), extends product life and improves productivity. Regardless of the industry or environment, remanufacturing of failed or malfunctioning equipment is a smart choice.

Lonnie Morris is global product manager with Rockwell Automation Repair Services in Milwaukee WI. E-mail: lrmorris@ ra.rockwell.com

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Maintaining Wastewater Treatment Systems

Continuous vibration monitoring of pump stations at a major wastewater treatment plant pays off for the City of Tampa.

The Howard F. Curren Advanced Wastewater Treatment Plant (HFCAWTP) is a state-of-the-art facility that treats all wastewater discharged from the City of Tampa, fl, system from approximately 100,000 accounts. The plant has a license capacity of 96 million gallons per day (MGD), with an average daily flow of 60 MGD. The final product, or effluent water, is discharged to Hillsborough Bay or used as reclaimed water for cooling and irrigation. This high-quality water meets all state and federal requirements.

1007_wastewater1The plant has developed and is currently executing an optimization program that includes automation of processes and procedures when possible, and reducing scheduled vs. unscheduled downtime and maintenance, transitioning from a reactive to proactive organization ready to address issues and problems. Because the Howard F. Curren facility is the City of Tampa’s (COT) only wastewater treatment facility, it is imperative to minimize flow interruptions, unscheduled downtime and overflows.

The use of reliable pumps to transport wastewater from various locations in the city is critical for maximizing flows and maintaining biological efficiencies by producing a constant flow. When the pumps fail, backup pumps are used to keep the flow going. Failures often can be very damaging to the pumps and auxiliary equipment. Installing a protection system that monitors the vibration levels and can be integrated to a shutdown circuit can minimize flow interruptions and the amount of costly damage to that equipment. The price of a new pump motor can be as high as $450,000; the cost to repair an existing unit can approach $175,000 after a catastrophic failure. In an effort to help prevent these types of failures, the HFCAWTP and Connection Technology Center, Inc., a vibration analysis hardware and process equipment manufacturer, investigated different equipment and system options for monitoring this crucial application.

The application
There are eight major pump stations that collect the wastewater and deliver it to the treatment plant. Each major pump station has many smaller stations that will feed it—either through pump systems or gravity feed. There are approximately 224 pump stations within this system.

Three types of pumps setups are typical of these stations: Direct coupled, submersible and vertical shaft. The direct coupled stations will have the motor and the pump on the same floor, with the motor in an overhung position and supported over the pump. The vertical shaft stations will have the motor and clutch or VFD-controlled motor typically two stories above the pump, with the shaft coupled in one or two places.

Each major lift station has three or more motor-pump systems, with one pump typically running at a time to ensure system redundancy. Major failures can cause overflow issues, not to mention extensive damage or complete failure with auxiliary equipment such as valves, VFDs and wiring.

PROTECTING CRITICAL SYSTEMS IN FLORIDA

The City of Tampa’s Howard F. Curren Advanced Wastewater Treatment Plant (HFCAWTP) uses vibration analysis hardware and process controller equipment to protect critical machinery against damage due to mechanical failures or environmental changes. This system helps protect critical equipment with relays to trigger alarms or shutdowns, while integrating to the main plant’s Supervisory Control And Data Acquisition (SCADA) system for continuous monitoring. This helps ensure survivability and prevent unscheduled downtime and costs.

For the purposes of determining where to install a protective system, the major stations were identified as the areas to have the critical equipment monitored.

Vibration considerations
The general vibration considerations that are periodically monitored in the pumping systems at this plant include cavitation, mechanical failure and mis-alignment. Cavitations often will accelerate the mechanical failures of the pump, such as discharge valve failures and impeller wear. Faults due to mechanical issues also are accelerated due to increased flow. Possible mechanical failures include breaking or dropping the impeller or impeller shaft and/or bearing failures.

Other unique vibration considerations at this plant are associated with the alignment of the vertical shafts to pumps, requiring coupling shafts up to 20 feet in length, and accessibility of the equipment, which is often very difficult.

1007_wastewater01The application is made even more challenging by the fact that these remote pump stations are not manned, and the periodic monitoring may not be sufficient to capture any transient type of faults that could lead to failures.

Process/protection considerations
Periodic monitoring may be sufficient to identify general, long-term machinery conditions, but to capture transient conditions that can cause catastrophic failures, continual monitoring is required. Because the pump stations are unmanned, a system is in place to alert a technician at the plant that there is an issue with the pump station equipment. If there is an issue, corrective actions may be necessary in order to prevent the premature failure of the equipment and overflows.

Ensuring this capability required integration of the vibration system with the plant SCADA system. The output parameters of the vibration system, in this case 4-20mA output proportional to the overall vibration levels of the equipment, will feed into the SCADA system and allow the technician to observe a “status” of the equipment at the stations. This is an ideal situation, as many issues can be identified quickly before the effects of a catastrophic failure occur. However, this integration is often difficult based on the available resources of both the SCADA system and the plant personnel to integrate this.

1007_wastewater02Another solution that can be implemented as a stand-alone or integrated with the SCADA system is to provide a local relay or shutdown system that can be tied into the motor control circuit to shut down the pump system in the event of a catastrophic failure. Such a solution can limit the extent of the damage to the pump and limit/prevent the damage to auxiliary equipment, as well as minimize interruptions of the flow to the plant.

Equipment & system selection considerations
For the initial unit, a system of low-cost accelerometers mounted to mounting targets connected to a remotely mounted process controller enclosure was specified, with integration to the main plant SCADA system. The equipment was selected based on the following considerations.

Accelerometer selection…
To select the proper accelerometer for the monitoring of components, the following vibration frequency criteria was taken into consideration:

  • Pump vane frequencies
  • Pump cavitations frequencies
  • Motor fault frequencies
  • No clearance issues that would require low-profile sensors
  • Historical vibration data and experience with the equipment

Frequencies for detecting vibration faults should be within the frequency response of the selected accelerometer. For accelerometer specification, the motor and pump vane frequencies did not require a special frequency response, and a standard, 100 mV/g accelerometer, with a frequency response between 0.5 – 15000 Hz, was selected for this application.

Mounting hardware selection…
To provide the optimum vibration transfer between the machine surface and the accelerometer, a mounting system that utilizes the full frequency span of the accelerometer needed to be considered. A mounting target attached to the prepared machine surface (prepared with an installation tool kit [MH117-1B] that can be resharpened for multiple installations) with an adhesive was selected. The adhesive-mounted target facilitates excellent vibration transfer, and the full frequency range of the sensor can be utilized. Another advantage to the adhesive-mounted target is that the machine surface does not need to be drilled and tapped. A flat mounting target with a ¼-28 threaded hole was selected for this function.

Cable selection…
In light of the environment, the cable connecting the accelerometer to the enclosure needed to be robust, chemical resistant, water resistant and reliable in caustic conditions. A Teflon-jacketed cable with molded connector and stainless steel locking ring was chosen.

Signal conditioner selection…
Because of the required inputs into the process controller, a field-configurable signal conditioner with a display that can be easily seen in a variety of lighting conditions was chosen, as each pump that is monitored can have unique vibration levels. The signal conditioner also needed to be able to re-transmit the 4-20mA outputs in order to eventually integrate with another process control system and SCADA. Power for the signal conditioner(s) and the sensors are provided by the internal process controller.

Process controller selection…
The selected process controller allowed for field configuration, incorporated a display that permitted visual identifi- cation of the vibration level and included a power supply for the signal conditioners.

The ability to set up two different alarm levels, as well as a time delay to prevent “nuisance alarms” that might occur if a spike in vibration levels due to a transient event also was determined to be important for this system. The controllers are powered from 120 VAC input into the enclosure, which was provided by the facility.

1007_watewater_fig1Enclosure selection…
The selected enclosure allowed for easy wiring into and out of it. This enclosure also has proven to be unaffected in a highly corrosive atmosphere. The process controllers and the signal conditioners were factory-wired. The wiring of the sensors into the enclosure, any re-transmitted signals out of the enclosure and 120 VAC power into the enclosure were done through pre-defined cable entry and exit cord grips/conduit. The wiring was attached at a termination block that was clearly identified for the type of connection required. (See Fig. 1 for an example of the termination identification.)

The easy wiring minimized the time required to install sensor cables and integrate the components of the system into the enclosure, and ensured that the system was completely integrated prior to delivery.

Financial analysis
Justification for the Howard F. Curren Advanced Wastewater Treatment Plant project was determined based on a review of the approximate cost of a pump station motor repair versus the price of a typical two-channel monitoring system. The repair cost for an 800 hp motor could go as high as $175,000. The price of the monitoring system was approximately $2500—or roughly $1500 per measurement point.

The initial approval to outfit one major lift station was decided in 2006, and a unit has been in service since that time. The project justification was further underscored by a subsequent motor failure at another pump station. The estimated cost of that motor repair was close to $160,000—a fact that renewed interest in the relatively low-cost 24 hour protection device.

Approved monitoring setup
The approved system was to be used as a monitor to notify the plant of problems with the pump or motor, especially during off-hour operation. As shown in Fig. 2, this system consists of two permanently mounted sensors, with cable from the sensor wired to the enclosure. Mounted inside are: two process controllers, two signal conditioners, and two transmitters (for the 4-20 mA output process signals). The box also has a window to permit viewing of the process controller displays for overall vibration level readings.

  • The signal conditioner was scaled to less than 0.51.0 IPS, with a frequency range between 5 and 50 Hz.
  • Two relay outputs were configured based on experience in required alarm settings. The baseline vibration on the machine was observed to be 0.2 IPS, peak. From there, relay/alarm settings were set at 0.35 IPS, peak for the first level, and 0.65 IPS, peak for the second alarm level, with time delays of approximately 30 seconds for each level. If the vibration does not maintain that amplitude (or greater) for that length of time continuously, the relay does not activate. The levels, time delays and relay action (latching, latching with clear, manual reset) can be adjusted on the process controllers.
  • The system was mounted at a lift station with a flow capacity of approximately 35 MGD and connected to the main plant SCADA system. Relays are in place to shut down the pump/motor if there is an event that could cause serious damage to the equipment. Sensor location selection The sensor mounting locations were selected based on historical data and accessibility of the measurement location point. In order to monitor the pump and motor, for the direct driven system, a sensor was placed on both pump and motor. Enclosure mounting location selection The cable was routed from the pump and motor to the enclosure, which was mounted on a fixed wall. This is located near the shut-off switch, which was installed to protect the pump and motor equipment. Major benefits of the system can be seen in the following features and capabilities:
  • A turn-key system solution
  • Easy wiring terminations
  • Field-configurable signal conditioners and process controllers
  • Allows for re-transmission of the process signal
  • Allows for integration into a SCADA system
  • Allows for settings to shut down the equipment
  • Two relays with independent input levels with latching options
  • User-friendly components
  • Permits access to “live” data to hard to inaccessible points
  • Offers multi-functions vibration and temperature

Results
The installed system has identified possible pump cavitations occurring in the early morning hours during low-flow periods. These types of cavitations can escalate rapidly, putting a pump and motor in danger. For example, another station at this plant that did not have the approved system in place subsequently failed—possibly due to cavitation—requiring repairs to the equipment and costly unscheduled downtime.

Conclusion
The following factors were critical in convincing management that vibration monitoring has benefits to the Predictive Maintenance Program and City of Tampa (COT) and could be considered for expansion into other pump stations:

  1. Cost of the equipment is much less than the cost of repair or replacement of pump and motor
  2. The system protects critical equipment with relays to trigger alarms or shutdown
  3. 4-20mA outputs feed into SCADA system for continuous, online monitoring.
  4. Continuous monitoring can identify possible issues that would not have been observed otherwise.
  5. Protecting pump and motor systems during increasedflow events can reduce unscheduled maintenance or repair by alerting the plant of issues before they become catastrophic.
  6. The system permits easy access of dynamic data for route collection and/or detailed analysis.
  7. Required maintenance will be identified more precisely and accurately, thus reducing unscheduled downtime, repair cost and overflow issues.

Tom LaRocque is the engineering manager for Connection Technology Center, Inc., in Victor, NY. A Certified Vibration Analyst: Category III, he holds a B.S. in Engineering from Clarkson University. LaRocque is a member of the Central New York Chapter of the Vibration Institute. Telephone: (585) 924-5900 ext. 817; e-mail: tlarocque@ctconline.com

Gary Kaiser is a senior application engineer for Connection Technology Center, Inc. A Certified Vibration Analyst: Category III, he previously worked for Eastman Kodak for 23 years. While at Kodak, Kaiser spent 9 years in the vibration analysis group. He also is a member of the Central New York Chapter of the Vibration Institute. E-mail: kaiserg@ctconline.com

Joe Spencer is a mechanical specialist with the City of Tampa, fl. A Certified Vibration Analyst, he has 30 years of field maintenance experience.

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Viewpoint: Notice Anything New?

jane_alexander

Jane Alexander, Editor-In_Chief

Now that you’ve read through this month’s magazine, it’s fair to ask if you’ve noticed anything new on our cover and in our pages. You should have. That’s because we’ve made changes in some wording and visual elements to support a sharpening of our focus. With this issue of Maintenance Technology, we formally have become “your source for capacity assurance solutions.” We trust that you will find value in this move.

Capacity assurance is not a new term—it’s been around for many years. Those of you in the maintenance and reliability community are no doubt quite familiar with it, since it’s all about maximizing uptime, minimizing downtime, running safely, cleanly, efficiently and profitably.

The task of keeping modern plants running at peak capacity, however, goes well beyond the area of traditional maintenance and reliability (although those elements are more important than ever as key capacity assurance components). It encompasses all activities necessary for ensuring that your equipment and systems are capable of operating at prescribed output and quality levels whenever scheduled or needed. In other words, capacity assurance is the “fat rabbit” everyone in a company is chasing 24/7/365—and we do mean everyone. Therefore, being successful in this chase requires a “holistic,” integrated approach to maintenance, operations and management.

We at Maintenance Technology have long recognized how critical it is for you in industry to be able to catch the capacity assurance rabbit quickly—continuously. In fact, we’ve been championing the types of integrated approaches and solutions that help you get the job done for more than 20 years. Today, though, and into the future, with so much riding on a company’s ability to assure capacity, we feel compelled to be more specific in our own approach.

Time has marched on. Technologies, applications, operating parameters and business environments have changed. So have your jobs, your time constraints and your information needs. What has not changed is the importance of capacity assurance across your operations—and the fact that countless organizations are pushed to get more, more, more of it with less, less, less.

Putting our editorial spotlight on “capacity assurance” as opposed to “plant equipment reliability, maintenance and asset management” will allow us to better serve you and other busy readers. You’ve been seeing us move in that direction for some time, placing increased emphasis on failure avoidance and the operating equipment and systems where preventive and predictive maintenance technologies are applied than we have in the past. Our quarterly supplements, “Utilities Manager” (focusing on successful demand-side energy solutions for plants and facilities) and “The Fundamentals” (taking a back-to-basics approach to maintenance and reliability), are two other prime examples of our sharpened focus. Now, going forward, you can expect even more great “new” things from us.

You know it and we know it… Excellence in capacity assurance is vital to industrial profit and world-class quality. In our view, it’s one of the fattest rabbits out there. Maintenance Technology is proud to be your partner in this noble and exciting chase.

 

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