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    Motor Talk

    I wrote a blog in the past recommending the MCC as the best testing location with reasons supporting that recommendation. However, as we know the “best location” is more often than not dictated by other factors. Some of those “other factors” are what I will be discussing today.

    Time is a factor that is one of the most compelling dictators as to the location from which data is collected. When time is a factor, the location that allows the fastest data collection MCC vs. In-field disconnects would be the more appropriate location. The MCC is a more compact location without time loss for moving to different locations. Although, if there are VFD’s involved, as in my last job, the In-field disconnects may be a better option. The last job I was on had 30 motors to be tested both On-line and Off-line in 2 ½ days (here is the time part). At first the MCC would seem the best place for the testing. During the morning planning it was revealed that all but 3 of the 26, 480VAC motors were controlled by VFD’s.  In addition there were four 4160V motors.

    The time required  for disconnecting, testing, reconnecting, restarting, testing, and moving to the next location, was estimated to be 2 - 2 ½ hours per motor for testing from the MCC. With 30 hrs of available time, testing from the MCC was not going to work. The site disclosed that every 480VAC motor had a local disconnect next to the motor. While this is normally not the “ideal” setup, the motors were grouped together in clumps of 3 to 6 at each location. This allowed us to test from the local disconnect without having to unwire the VFD’s, as the testing was completed from the load side of open disconnect for the offline testing. Subtracting the time needed to unwire and rewire the VFD’s, we were able to complete the required tests in the time allotted. If in your plant or customer site the test locations are set in the procedures, then plant procedures are also a factor. In this case there is no option. One must test from the location cited in the procedure or request a deviation to test from another location. Keep in mind that when requesting a deviation you must have the supporting information ready to present.

    Location of the motor is another factor that may change your plans. The motor may be located in a hazardous environment, which will cut down your options. I have in the past identified a ground fault while testing from the MCC. Then, the normal procedure is to test at the motor to isolate the fault in either the motor or the feeder cables. When unable to use an ignition source in the hazardous area, I had the motor removed from the area and tested it in a “safe” area to find the problem was in the feeders, as I had no indication of a problem in the motor.

    It is always best to test the entire motor circuit. Consider extending the allotted time, using additional testers or working longer days to be able to complete testing. Another option is to fully test as many assets as possible and test the missed assets at a later date. When the entire circuit is not tested, a problem may be missed.

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    Motor Talk

    I’m writing this for those that will probably never read it. Those of you still trapped in the mid-20th Century. I’m also writing this slow because you don’t read very fast and it will take you forever to catch up. You are the guy that doesn’t get it, you come up with every excuse possible so that you don’t have to test your motors. “As long as I have my meter and my “wiggy” I don’t need any other test equipment.” Oh and another great one, “That motor was running when I shut it down and it’s gonna run when I hit that start button.” So how do explain your motor failures?

    I could lay all kinds of statistics on you like the 1986 EPRI Study that showed that greater than 47% of medium and high voltage motor failures were electrical and that motors in your plant probably last less than 5 years when they should last 20 or more. I bet that you don’t realize that almost 25% of all power consumed in the United States is consumed by electric motors. In most industrial facilities, motors consume upwards of 70% of the power. I could also tell you that when you go to get a spare motor out of the warehouse, you have a 30% chance of selecting a bad one. Taking simple steps and routinely monitoring your motors can result in a substantial savings in operational costs not to mention the fact that plant reliability will increase significantly.

    Electric motor testing is a “no brainer,” and those with no brains or significantly lacking common sense don’t do it. 

    So when you are done not reading this go back to where you reside, in your Corvair, to the mid-20th Century.

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    Motor Talk

    This is a question I hear often, and I’m always glad when I do because it’s not that tough to answer.  This question always makes me think of an expression I’ve heard in the past; “you can never be too rich or too thin”.  Now we know that one can in fact be too thin, just pick up a copy of any tabloid and you’ll see that in the entertainment industry in particular.  I suppose you could be too rich too, though that seems less common, particularly these days.  When it comes to motor testing though, going overboard isn’t that big of a concern.

    Both Energized (Dynamic/Online) and De-Energized (Static/Offline) motor testing methodologies are generally safe for the motors where they are applied.  De-Energized EMT does in fact apply very low amounts of current for the purposes of measuring electrical resistance and impedance, but the amounts of current are comparable to what a typical multimeter applies when testing resistance.  We’re talking about milliamps of current at a miniscule level of voltage.  There’s no danger that you’re exceeding the withstand voltage of the winding insulation or introducing enough current through the windings to produce dangerous amounts of heat.

    Energized EMT is different in what data it provides, as well as how it gathers that data.  In Energized EMT, the motor is obviously energized (hence the term) so the tester doesn’t apply any voltage or current at all.  In Energized EMT the tester monitors the voltage and current levels in the motor circuit, and detects the impact of electrical and mechanical conditions on the operation of the motor.  Energized EMT is completely passive, and therefore non-destructive.

    There are testing methods utilized on motors that do have an impact on the condition of the motor itself.  Hi-pot testing is a test method that has been surrounded by controversy of late, due to the fact that voltages that approach the withstand level of the motor winding insulation are used to test for breakdowns in the insulation itself.  If performed improperly, hi-pot testing can continue to deliver damaging levels of voltage past when a breakdown has been discovered.  This typically occurs with older hi-pot test sets, which rely on the test technician to interrupt the test when a breakdown occurs.  Newer testers are microprocessor controlled, and will interrupt the flow of test current within a few cycles of an insulation breakdown, reducing the likelihood of damage to the winding insulation.  Despite these advances in tester technology, many motor end users still shy away from hi-pot testing.

    When it comes to Energized or De-Energized EMT however, these concerns aren’t applicable.  Your frequency of testing can be determined based on factors such as operating environment of the motor, or asset criticality.  So in most cases, you really can’t test too much.

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    What You Need to Know about Service Factor
    Motor Talk

    Motor “service factor” is probably the most misunderstood value on a motor nameplate.  To most it seems quite simple; if it is a 1.0 you can run a motor to 100% load, if it is 1.15, then it can be loaded to 115% of its rated load.  That’s simple enough, right?  Wrong!  It is not that simple.

    First let’s look at what the National Electrical Manufacturers Association (NEMA) has to say about service factor:  (NEMA MG-1)

    In order to get optimum performance and full longevity form your motors, it is important that you fully understand service factor.

    1.42 SERVICE FACTOR—AC MOTORS
    The service factor of an AC motor is a multiplier which, when applied to the rated horsepower, indicates a permissible horsepower loading which may be carried under the conditions specified for the service factor (see 14.37).

    14.37.1 General
    A general-purpose alternating-current motor or any alternating-current motor having a service factor in accordance with 12.52 is suitable for continuous operation at rated load under the usual service conditions given in 14.2. When the voltage and frequency are maintained at the value specified on the nameplate, the motor may be overloaded up to the horsepower obtained by multiplying the rated horsepower by the service factor shown on the nameplate.

    When the motor is operated at any service factor greater than 1, it may have efficiency, power factor, and speed different from those at rated load, but the locked-rotor torque and current and breakdown torque will remain unchanged.

    A motor operating continuously at any service factor greater than 1.0 will have a reduced life expectancy as compared to operating at its rated nameplate horsepower. Insulation life and bearing life can be reduced by the service factor load.

    Now service factor should be abundantly clear, right?  Wrong again!  If we delve further into NEMA MG-1, we find stipulations for exceeding service factor of 1.0:

    1. To accommodate inaccuracy in predicting intermittent system horsepower needs.
    2. To lengthen insulation life by lowering the winding temperature at rated load.
    3. To handle intermittent or occasional overloads.
    4. To allow occasionally for ambient above 40°C.
    5. To compensate for low or unbalanced supply voltages.

    NEMA’s reference to “intermittent” is also a major point of confusion.  How do I define intermittent?  The best advice here is to provide temperature monitoring of the motors that are running overloaded within service factor. If they approach or exceed insulation design temperatures then the load should be reduced.

    NEMA does add some cautions when discussing the service factor:

    1. Operation at service factor load for extended periods will reduce the motor speed, life and efficiency.
    2. Motors may not provide adequate starting and pull-out torques, and incorrect starter/overload sizing is possible. This in turn affects the overall life span of the motor.
    3. Do not rely on the service factor capability to carry the load on a continuous basis.
    4. The service factor was established for operation at rated voltage, frequency, ambient and sea level conditions.

    In order to get optimum performance and full longevity form your motors, it is important that you fully understand service factor.

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    Electric Motor Testing: Dealing with Unrealistic Time Expectations
    Motor Talk

    Early in the development of an electric motor testing program as an onsite technician, I had the experience of working with a customer’s electrical engineer. This individual had little experience or was just slightly familiar with motor testing.  Likely he may have heard about this “new fangled” method of monitoring motors at a convention or seminar and decided that he was going to micro-manage my efforts to implement a motor program at “his” site. Somewhere he had gotten the idea that all motor testers and tests were the same and that his research indicated an offline test should take about four minutes to complete. With this arbitrary four-minute time frame he discovered through “research”, the electrical engineer concluded that 15 motor tests and hour would be the minimum standard.  

    When you’re in the field using one specific brand of a motor tester, it can realistically take anywhere from 10 to 15 minutes per motor. That is just the minimum amount of time needed for the tester to compile data and does not include locating the starter, following lock-out/tag-out procedures, obtaining permits, putting on PPE, and connecting the cables.

    While this process may not seem to be the most cost effective when you add up the time spent doing paperwork and practicing safe work procedures, keep in mind that all it takes is preventing one process failure to justify this time and expense.

    I spent two weeks educating the electrical engineer about what tests were needed for a quality program and the timeline required for those tests, including “his” site’s safety requirements. The effect that the tests were going to have on “his” program’s “minimum standard” of testing 15 motors per hour was something he did not want to hear. To drive my point home, and to expose him to a real-world scenario, I decided to invite the electrical engineer to a day of offline testing. He was going to spend the whole day with me, from loading equipment in the morning while at the office until returning at end of the day. He seemed to be a good sport about the whole thing until it became apparent that I was right and he was wrong.  After the third motor test (which happened to occur this time right before lunch) there suddenly was a meeting he couldn’t miss and I didn’t see him again until the next day.

    When we did manage to meet up again there was a definite change in his approach as to how the program should be managed. The management of the motor program was turned over to the Predictive Maintenance (PdM) Department with reports copied to him.

    Dealing with unrealistic expectations is a very common problem that on-site technicians have to deal with on a regular basis. As a traveling technician, the problem lies in the negotiations of the service and not having the safety procedures and other required safe work requirements, how long it takes to fulfill those requirements, and the understanding between both parties. Having unrealistic expectations can, and does, lead to a misunderstanding of how many motors can be tested in a given timeframe.  So, if you run into a similar situation, keep your cool. Showing a skeptic the time it takes to perform a motor test in the field can help convey what is, and what is not, a realistic expectation.

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    Snap Judgments - Don’t Make Them!
    IR Talk

    I have been instructing IR with The Snell Group for a number of years, and it’s a very rewarding job. I love the moment in class when I see a student’s look of excitement that indicates they have just learned something they did not know before that moment.

    One of the first things I try to pass on to a class is to fight the urge to rush a snap judgment on a thermal image. It is human nature to want to solve a problem faster than the next guy. Quick and uninformed problem solving usually leads to an improper diagnosis.

    When diagnosing an IR image many questions should be asked, and properly answered before labeling the cause of a thermal anomaly. The first question to ask should be, “Is this an image of a problem, or is this a normal thermal signature for this object?” I can’t imagine anything would not be considered a normal thermal pattern.

    If the thermal pattern is considered abnormal, then the task becomes to find out why it is abnormal. This is where I’m going to raise some eyebrows of some readers. Once the thermal pattern is considered to be incorrect, the job of the thermagrapher is complete. The thermographer should not try to diagnose the problem. Now I know some of you want to hit the back button on your browser right now, but hear me out first.

    The role of the thermographer is to capture thermal images of problems. I can take any individual that has absolutely no electrical or mechanical experience, and have that person doing limited thermography in a day or two. All I need is to first teach them how to operate a thermal imager. Then, I would show the person a thermal image of a widget that is considered normal. I could set them free in a building full of these widgets and tell them to find the ones that don’t look thermally like the control image. When he or she finds the widget that is not thermally like the control image, I would then ask him or her, “What is causing the anomaly?” This is where the process breaks down. With no background knowledge about a widget’s inner workings, the person is clueless as to the cause of the problem.

    Diagnosing a thermal anomaly requires other questions to be asked with corresponding correct answers.

    For electrical problems, one should ask some of the following questions:

    • Is the connection lose
    • Is the connection corroded?
    • Is the connection over tightened?
    • Is the connection the wrong size?
    • Is the connection overloaded?
    • Is the connection improperly cooling?
    • Is there a load balance issue?
    • Is there a harmonics issue?

    For mechanical questions, similar questions could be asked:

    • Is the component out of alignment?
    • Is the component properly lubricated?
    • Is there metal on metal contact within or around the component?
    • Is the component over pressurized?
    • Is the component overloaded?
    • Is there a bearing failure within the component?
    • Is there a clogged or plugged line within, or going to, the component?

    These are a few of the many questions you should be asking. As you can see, there are other tools and skill sets that must be employed in order to properly diagnose the cause of an abnormal thermal pattern. If you must try to solve what is causing a thermal anomaly without further investigation, I would suggest you list everything that could possibly cause the thermal issue in the image. Snap diagnostics can lead to wasted time, money, and a downgrade in your credibility. Always ask questions, take your time, and don’t rush to judgment!

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  • 11/07/16--05:25: EMT Workspace
  • NFPA
    Motor Talk

    How you keep your workspace in the field can say a lot about what kind of technician you are. Other telling signs are how you approach safety; your own and that of your assistant. How meticulous are you in collecting and analyzing data? What condition is your equipment in?

    When we look at the in-field work area, how do you post or identify what work is being done and what restrictions apply to the immediate are? At most facilities, the safety department has already determined how this is to be done. If this task has not been completed at your work site, there are guides that can help you determine the restrictions and the standoff distances required. The most important of these guides is NFPA 70E. Within this document are PPE and necessary qualification guidelines, along with different approach distances depending on the type of equipment being inspected. Being familiar with these requirements along with implementing and enforcing them is crucial to workplace safety; not just for you, but for all those around you.

    Another question to consider is: how do we keep unnecessary personnel out of our work area? After all, we don’t need any spectators and if there isn’t a valid reason for a person to be in your work area, they shouldn’t be there. When determining what type of barriers to use and where to place them, we can refer again to NFPA 70E where you will find recommendations for barricade types and required distances. Generally speaking, the barriers should keep unprotected (no proper PPE) people far enough away that they will be safe from injury in the case of an incident. The barricade should be recognized throughout the facility something to NOT cross under any condition without proper clearance from you. Danger tape with proper signage clearly stating what the hazard is and who can authorize entry is necessary. Each facility has their own version of this type of barrier, but if you work at a facility that does not, you should develop one in conjunction with the safety department.

    Keeping a neat, orderly work area not only makes it easier for you to find tools and equipment, it’s safer. If things are scattered all over the floor, you’ve just created a number of trip hazards. If equipment is piled haphazardly it can fall over into energized or rotating equipment.

    If you liked this post, you might enjoy our Knowledge Briefs Newsletter. Receive new posts delivered right to your inbox every week! Sign up here.

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    8 Steps for Gathering Effective Motor Testing Data - Part One
    Motor Talk

    It is estimated that almost half (45%) of global electricity is used by electric motors. Electric motors drive all parts of many industries, from power generation to water and food supply to consumer products. The importance of electric motors in modern society cannot be under- stated. It is because of this large role that it pays huge dividends to keep our electric motors running efficiently through a quality reliability program that includes Electric Motor Testing (EMT) and Motor Circuit Analysis (MCA).

    Electric motor test instruments have become extremely effective reliability and diagnostic tools for motor and motor circuit testing. Significant improvements in motor longevity and overall plant reliability may be achieved through proper implementation of this established technology. But, as with any new program there will be growing pains. These will start immediately upon receipt of your test equipment. Who should conduct the testing? When should testing be conducted? Do we have procedures in place? If not, what procedures need to be developed? What should be tested? The following paper provides eight steps that, if followed, will enable successful and effective electric motor testing data for your reliability program.

    Step 1 - Personnel Preparation

    As with any endeavor, the key to success is knowledge of the task to be performed. With motor testing this means a thorough understanding of the equipment to be used including test capabilities, diagnostic strengths/weaknesses, and in-depth knowledge of the equipment to be tested.

    Equipment capability information is usually provided by the motor tester manufacturer through initial training. A comprehensive knowledge of motor operation and failure modes is also necessary, but it’s not something easily obtained and is rarely provided by the test equipment manufacturers. Apprentice training, experience and specialized training are the most effective means of gaining the necessary knowledge.

    Developing proficiency is another challenge. This where we don’t want to learn by our mistakes. Making erroneous calls and missing significant problems will detract from the credibility of the equipment, the technician, and the reliability program. Most industrial facilities have spare motors on hand, so when first starting to test, test warehouse spares, then expand to acceptance testing. This will provide you with time to learn software, test capabilities and develop the proficiency to test operational motors with competence and expedience.

    Step 2 - Preparation for Equipment to be Tested

    What equipment should be tested? Perspectives can vary widely in answer to this question. Criticality is in the eye of the functionary at your facility. What is critical to production may not be as critical to the maintenance or safety departments. The best way to address criticality is from four basic perspectives; operational, safety, logistical, and environmental.

    Operational Criticality is straightforward and is based primarily on operating voltage:

    1. Medium / high voltage / frequent starts
    2. Medium / high voltage
    3. Low voltage / frequent starts / high horsepower
    4. Low voltage / high horsepower
    5. Critical VFD powered motors
    6. Non-redundant critical motors

    Medium and high voltage equipment will cost significantly more to repair or replace and may require prolonged lead time for replacement. Frequent starts, at any voltage, will fail more frequently than motors that run continuously or start infrequently. Motors that are driven from VFD’s normally run hotter and are subject to more rapid thermal degradation of the insulation. Some motors of fractional horsepower may be critical, i.e. a ¼ HP lube oil pump for a 6000 HP sleeve bearing motor may be as critical as the 6000 HP motor.

    Safety Criticality is simple and straightforward as well. Can someone be killed or injured if this equipment fails?

    Logistical Criticality is based upon availability of repair facilities and replacement parts. In this world economy, parts may have to be manufactured halfway around the globe. This entails a prolonged downtime for the failed equipment and a possible significant effect on the process.

    Environmental Criticality is, again, straightforward; will failure of this equipment cause environmental damage such as a toxic effluent release or excessive air pollution?

    Get all of the key players involved to determine criticality of equipment. Sit down and discuss priorities, maintenance difficulties, safety, and logistical issues and come up with a list of critical assets. Once an equipment list is developed it should be organized into routes. Plan so that a maximum number of assets can be availed in each location. Jumping around reduces productivity. Routes should have a recurring periodicity based on criticality.

    Next month we will cover some additional steps to follow to help you establish and maintain a successful and effective electric motor program by getting reliable testing data.

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    8 Steps for Gathering Effective Motor Testing Data - Part One
    Motor Talk

    In last month’s posting, we briefly discussed about the importance of motors and motor testing. We also deliberated about the first step to take—personal preparation—and how they should understand the tester equipment, motor operation, and developing proficiency in testing. We then turned our attention to the second step—preparation for equipment to be tested—and criticality of equipment from multiple perspectives; operational, safety, logistical and environmental.

    This month, we discuss the next three steps to take to gathering effective electrical motor data.

    Step 3 – Preparation of Test Equipment

    In order to perform motor testing effectively, the test equipment should be in optimal condition. The tester should be in calibration with the most recent updates to the operating software (Note: when updating software be aware of possible compatibility issues. New software updates should clearly explain any operating systems (OS) that are and are not supported.) Software upgrades are essential. Many times they correct inaccuracies or provide important safety procedures or steps. The associated equipage should be inspected and tested, as applicable, to prevent problems when in the field conducting tests. Conduct a check of the equipment the day before testing is scheduled. A simple generic checklist will help with the readiness of the equipment:

    Checklist for Effective Testing:

    • All batteries operable and charged
    • Deep cycle batteries as required
    • Test leads are free of any nicks or cuts in the insulation
    • Voltage clips or test clips are clean and free of any foreign debris or corrosion
    • Voltage clips or test clips are snuggly threaded or make a tight fit on test leads
    • Current probes have good batteries (if applicable)
    • Inspect power cords for nicks and breaks in the insulation
    • Current probes jaws are clean and free of any foreign debris at both the top and hinge point
    • Current probe spring tension is good
    • Test lead connection points on the test instrument are clean and free of dust and foreign debris
    • All electrical and data port cables on your test instrument are properly connected.

    Step 4 – Check Operational Status of the Tester

    Prior to acquisition of any test data, a quick operational test of the motor test instrument should be conducted. Use of a small test motor or stator will verify that the de-energized test data acquired, is accurate or repeat- able.

    To verify accurate energized data, perform a quick power quality test. Place all current probes on one phase cable and run the test. Compare bus phase voltages to acquired voltages and all of the amperage readings should be the same. Once you feel comfortable that you are collecting reliable data, begin your testing route.

    Step 5 – Maximize the Amount of Circuit Under Test (and the Amount of Load on the Circuit)

    If you are devoting the time to conduct testing, you should test as much of the circuit as possible.

    De-energized testing is usually conducted downstream of the de-energized contactor. With de-energized testing, connections made upstream will identify circuit anomalies between the connection point and the motor. Once identified, circuit isolation can be conducted and the source localized.

    8 Steps for Gathering Effective Motor Testing Data - Part Two 1

    Energized testing should be performed from the starter cabinet, connections should provide at least one local level of circuit protection above the point of connection, i.e. connect on the load side of the main breaker or load side of the fuses. Energized testing can be used to observe voltage and current FFT data to isolate spectral peak sources from upstream or downstream of the test connection point.

    8 Steps for Gathering Effective Motor Testing Data - Part Two 2

    Step 6 – Verify or Confirm Identified Anomalies

    When a potential problem is identified, it is just that; a potential problem. You should take steps to validate that it is, in fact, a problem. Sometimes erroneous data or unique characteristics of the equipment under test may give indications of a fault. You should perform all possible equipment checks and run additional correlative tests to validate your indications. Let’s say, for example, your test data indicates a possible high resistance connection.

    Check your test lead connections and re-run the resistance tests. If you get a current unbalance, check equipment loading to ensure that the unbalance is not due to insufficient loading. If load is sufficient save the data and run a quick power quality test, with all the current probes on one phase, to make sure that you do not have a defective probe. If you have Fpp (Field Pole Pass Frequency Sidebands) sidebands indicating possible rotor bar anomalies, check for swirl effect, current modulation, increased current draw for a given load and reduced

    in-rush current with longer start duration. These simple checks and correlative measures, can prevent erroneous data leading to bad calls, which can cast doubt on either you, the technology, or both.

    Next month, the last two steps will be examined.

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    8 Steps for Gathering Effective Motor Testing Data - Part One
    Motor Talk

    The past two month’s postings have revolved around what it takes to get good, effective motor testing data. The first month we examined personal preparation and preparation for equipment to be tested. Last month we discussed preparation of the test equipment, checking the operational status of the tester, maximizing the amount of circuit under test, and finally, verifying or confirming identified anomalies.

    In this last installment, we examine the last two steps to gathering effective electrical motor data.

    Step 7 – When Possible, Correlate with Other Technologies

    8 Steps for Effective Motor Testing DataWhen possible, you should correlate acquired data with other technologies. This will help confirm the existence of a problem and help quantify the severity. Sometimes reliability technicians tend to try and be a “one-man band.” But working together as a “RELIABILITY GROUP” will yield immeasurable results. Reliability technologies are like a set of wrenches or sockets, they all have specific purposes, but overlap.

    When they are used together you can work on most anything. The same with the reliability technologies; when used together you can diagnose most any problem. Proper use of vibration, ultrasound (shown in image), oil analysis, infrared and electric motor testing can provide a maintenance environment that will have minimal undiagnosed failures, resulting in maximum productivity and/or reliability.

    Step 8 – Generate Effective Reports (Communication)

    Believe it or not, reporting is probably the most important aspect of an effective motor testing program. The report is your deliverable. It can be the basis on how you are judged as a motor test technician. If you are a service oriented company, you already know or should know this. “In house” programs tend to sometimes neglect or minimize reporting which works to the overall detriment of the program. Budget expenditures are based on perceived value of the desired item. If your motor testing program does not appear effective, you may not be receiving the funding level you may require.

    Not only do you have to generate effective reports on identified anomalies, you need to generate updated reports on the overall success of the program. Work with management to establish performance metrics or KPIs. Bar graphs showing the number of identified and corrected anomalies should be posted in high visibility venues. Display monthly and yearly discrepancy counts, hopefully it shows a marked decrease. Display the budget reductions for motor rewind and replacement or the number of rejected motors not put into service that may have failed prematurely. Specific examples will help you illustrate your point. Use the data you gather not only to identify and repair problems, but also to demonstrate the effectiveness of the program.

    Communication, in addition to effective reports, is key to program success. You should have a network of communication established between yourself to middle and upper management, maintenance and production departments, as well as the other PdM technology personnel.

    Communications with planning, safety and logistics are also important departments for procedural and material support. Integrate your EMT results into the site EAM (Enterprise Asset Management) reporting to further support these types of communication. Other areas of important communications are with the motor shops, motor manufacturers, the tester manufacturer and your EMT knowledge provider.

    An effective motor testing program should be part of an effective reliability program. Use of the above 8 steps will provide your program with a significant and highly effective tool as part of a “World Class” maintenance program.

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    Motor Talk

    I’m writing this for those that will probably never read it. Those of you still trapped in the mid-20th Century. I’m also writing this slow because you don’t read very fast and it will take you forever to catch up. You are the guy that doesn’t get it, you come up with every excuse possible so that you don’t have to test your motors. “As long as I have my meter and my “wiggy” I don’t need any other test equipment.” Oh and another great one, “That motor was running when I shut it down and it’s gonna run when I hit that start button.” So how do explain your motor failures?

    I could lay all kinds of statistics on you like the 1986 EPRI Study that showed that greater than 47% of medium and high voltage motor failures were electrical and that motors in your plant probably last less than 5 years when they should last 20 or more. I bet that you don’t realize that almost 25% of all power consumed in the United States is consumed by electric motors. In most industrial facilities, motors consume upwards of 70% of the power. I could also tell you that when you go to get a spare motor out of the warehouse, you have a 30% chance of selecting a bad one. Taking simple steps and routinely monitoring your motors can result in a substantial savings in operational costs not to mention the fact that plant reliability will increase significantly.

    Electric motor testing is a “no brainer,” and those with no brains or significantly lacking common sense don’t do it. 

    So when you are done not reading this go back to where you reside, in your Corvair, to the mid-20th Century.

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    Motor Talk
    The Snell Group

    This is a question I hear often, and I’m always glad when I do because it’s not that tough to answer.  This question always makes me think of an expression I’ve heard in the past; “you can never be too rich or too thin”.  Now we know that one can in fact be too thin, just pick up a copy of any tabloid and you’ll see that in the entertainment industry in particular.  I suppose you could be too rich too, though that seems less common, particularly these days.  When it comes to motor testing though, going overboard isn’t that big of a concern.

    Both Energized (Dynamic/Online) and De-Energized (Static/Offline) motor testing methodologies are generally safe for the motors where they are applied.  De-Energized EMT does in fact apply very low amounts of current for the purposes of measuring electrical resistance and impedance, but the amounts of current are comparable to what a typical multimeter applies when testing resistance.  We’re talking about milliamps of current at a miniscule level of voltage.  There’s no danger that you’re exceeding the withstand voltage of the winding insulation or introducing enough current through the windings to produce dangerous amounts of heat.

    Energized EMT is different in what data it provides, as well as how it gathers that data.  In Energized EMT, the motor is obviously energized (hence the term) so the tester doesn’t apply any voltage or current at all.  In Energized EMT the tester monitors the voltage and current levels in the motor circuit, and detects the impact of electrical and mechanical conditions on the operation of the motor.  Energized EMT is completely passive, and therefore nondestructive.

    There are testing methods utilized on motors that do have an impact on the condition of the motor itself.  Hi-pot testing is a test method that has been surrounded by controversy of late, due to the fact that voltages that approach the withstand level of the motor winding insulation are used to test for breakdowns in the insulation itself.  If performed improperly, hi-pot testing can continue to deliver damaging levels of voltage past when a breakdown has been discovered.  This typically occurs with older hi-pot test sets, which rely on the test technician to interrupt the test when a breakdown occurs.  Newer testers are microprocessor controlled, and will interrupt the flow of test current within a few cycles of an insulation breakdown, reducing the likelihood of damage to the winding insulation.  Despite these advances in tester technology, many motor end users still shy away from hi-pot testing.

    When it comes to Energized or De-Energized EMT however, these concerns aren’t applicable.  Your frequency of testing can be determined based on factors such as operating environment of the motor, or asset criticality.  So in most cases, you really can’t test too much.

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    What You Need to Know about Service Factor
    Motor Talk

    Motor “service factor” is probably the most misunderstood value on a motor nameplate.  To most it seems quite simple; if it is a 1.0 you can run a motor to 100% load, if it is 1.15, then it can be loaded to 115% of its rated load.  That’s simple enough, right?  Wrong!  It is not that simple.

    First let’s look at what the National Electrical Manufacturers Association (NEMA) has to say about service factor:  (NEMA MG-1)

    In order to get optimum performance and full longevity form your motors, it is important that you fully understand service factor.

    1.42 SERVICE FACTOR—AC MOTORS
    The service factor of an AC motor is a multiplier which, when applied to the rated horsepower, indicates a permissible horsepower loading which may be carried under the conditions specified for the service factor (see 14.37).

    14.37.1 General
    A general-purpose alternating-current motor or any alternating-current motor having a service factor in accordance with 12.52 is suitable for continuous operation at rated load under the usual service conditions given in 14.2. When the voltage and frequency are maintained at the value specified on the nameplate, the motor may be overloaded up to the horsepower obtained by multiplying the rated horsepower by the service factor shown on the nameplate.

    When the motor is operated at any service factor greater than 1, it may have efficiency, power factor, and speed different from those at rated load, but the locked-rotor torque and current and breakdown torque will remain unchanged.

    A motor operating continuously at any service factor greater than 1.0 will have a reduced life expectancy as compared to operating at its rated nameplate horsepower. Insulation life and bearing life can be reduced by the service factor load.

    Now service factor should be abundantly clear, right?  Wrong again!  If we delve further into NEMA MG-1, we find stipulations for exceeding service factor of 1.0:

    1. To accommodate inaccuracy in predicting intermittent system horsepower needs.
    2. To lengthen insulation life by lowering the winding temperature at rated load.
    3. To handle intermittent or occasional overloads.
    4. To allow occasionally for ambient above 40°C.
    5. To compensate for low or unbalanced supply voltages.

    NEMA’s reference to “intermittent” is also a major point of confusion.  How do I define intermittent?  The best advice here is to provide temperature monitoring of the motors that are running overloaded within service factor. If they approach or exceed insulation design temperatures then the load should be reduced.

    NEMA does add some cautions when discussing the service factor:

    1. Operation at service factor load for extended periods will reduce the motor speed, life and efficiency.
    2. Motors may not provide adequate starting and pull-out torques, and incorrect starter/overload sizing is possible. This in turn affects the overall life span of the motor.
    3. Do not rely on the service factor capability to carry the load on a continuous basis.
    4. The service factor was established for operation at rated voltage, frequency, ambient and sea level conditions.

    In order to get optimum performance and full longevity form your motors, it is important that you fully understand service factor.

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    Electric Motor Testing: Dealing with Unrealistic Time Expectations
    Motor Talk

    Early in the development of an electric motor testing program as an onsite technician, I had the experience of working with a customer’s electrical engineer. This individual had little experience or was just slightly familiar with motor testing.  Likely he may have heard about this “new fangled” method of monitoring motors at a convention or seminar and decided that he was going to micro-manage my efforts to implement a motor program at “his” site. Somewhere he had gotten the idea that all motor testers and tests were the same and that his research indicated an offline test should take about four minutes to complete. With this arbitrary four-minute time frame he discovered through “research”, the electrical engineer concluded that 15 motor tests and hour would be the minimum standard.  

    When you’re in the field using one specific brand of a motor tester, it can realistically take anywhere from 10 to 15 minutes per motor. That is just the minimum amount of time needed for the tester to compile data and does not include locating the starter, following lock-out/tag-out procedures, obtaining permits, putting on PPE, and connecting the cables.

    While this process may not seem to be the most cost effective when you add up the time spent doing paperwork and practicing safe work procedures, keep in mind that all it takes is preventing one process failure to justify this time and expense.

    I spent two weeks educating the electrical engineer about what tests were needed for a quality program and the timeline required for those tests, including “his” site’s safety requirements. The effect that the tests were going to have on “his” program’s “minimum standard” of testing 15 motors per hour was something he did not want to hear. To drive my point home, and to expose him to a real-world scenario, I decided to invite the electrical engineer to a day of offline testing. He was going to spend the whole day with me, from loading equipment in the morning while at the office until returning at end of the day. He seemed to be a good sport about the whole thing until it became apparent that I was right and he was wrong.  After the third motor test (which happened to occur this time right before lunch) there suddenly was a meeting he couldn’t miss and I didn’t see him again until the next day.

    When we did manage to meet up again there was a definite change in his approach as to how the program should be managed. The management of the motor program was turned over to the Predictive Maintenance (PdM) Department with reports copied to him.

    Dealing with unrealistic expectations is a very common problem that on-site technicians have to deal with on a regular basis. As a traveling technician, the problem lies in the negotiations of the service and not having the safety procedures and other required safe work requirements, how long it takes to fulfill those requirements, and the understanding between both parties. Having unrealistic expectations can, and does, lead to a misunderstanding of how many motors can be tested in a given timeframe.  So, if you run into a similar situation, keep your cool. Showing a skeptic the time it takes to perform a motor test in the field can help convey what is, and what is not, a realistic expectation.

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    Snap Judgments - Don’t Make Them!
    IR Talk

    I have been instructing IR with The Snell Group for a number of years, and it’s a very rewarding job. I love the moment in class when I see a student’s look of excitement that indicates they have just learned something they did not know before that moment.

    One of the first things I try to pass on to a class is to fight the urge to rush a snap judgment on a thermal image. It is human nature to want to solve a problem faster than the next guy. Quick and uninformed problem solving usually leads to an improper diagnosis.

    When diagnosing an IR image many questions should be asked, and properly answered before labeling the cause of a thermal anomaly. The first question to ask should be, “Is this an image of a problem, or is this a normal thermal signature for this object?” I can’t imagine anything would not be considered a normal thermal pattern.

    If the thermal pattern is considered abnormal, then the task becomes to find out why it is abnormal. This is where I’m going to raise some eyebrows of some readers. Once the thermal pattern is considered to be incorrect, the job of the thermagrapher is complete. The thermographer should not try to diagnose the problem. Now I know some of you want to hit the back button on your browser right now, but hear me out first.

    The role of the thermographer is to capture thermal images of problems. I can take any individual that has absolutely no electrical or mechanical experience, and have that person doing limited thermography in a day or two. All I need is to first teach them how to operate a thermal imager. Then, I would show the person a thermal image of a widget that is considered normal. I could set them free in a building full of these widgets and tell them to find the ones that don’t look thermally like the control image. When he or she finds the widget that is not thermally like the control image, I would then ask him or her, “What is causing the anomaly?” This is where the process breaks down. With no background knowledge about a widget’s inner workings, the person is clueless as to the cause of the problem.

    Diagnosing a thermal anomaly requires other questions to be asked with corresponding correct answers.

    For electrical problems, one should ask some of the following questions:

    • Is the connection lose
    • Is the connection corroded?
    • Is the connection over tightened?
    • Is the connection the wrong size?
    • Is the connection overloaded?
    • Is the connection improperly cooling?
    • Is there a load balance issue?
    • Is there a harmonics issue?

    For mechanical questions, similar questions could be asked:

    • Is the component out of alignment?
    • Is the component properly lubricated?
    • Is there metal on metal contact within or around the component?
    • Is the component over pressurized?
    • Is the component overloaded?
    • Is there a bearing failure within the component?
    • Is there a clogged or plugged line within, or going to, the component?

    These are a few of the many questions you should be asking. As you can see, there are other tools and skill sets that must be employed in order to properly diagnose the cause of an abnormal thermal pattern. If you must try to solve what is causing a thermal anomaly without further investigation, I would suggest you list everything that could possibly cause the thermal issue in the image. Snap diagnostics can lead to wasted time, money, and a downgrade in your credibility. Always ask questions, take your time, and don’t rush to judgment!

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  • 11/07/16--05:25: EMT Workspace
  • NFPA
    Motor Talk

    How you keep your workspace in the field can say a lot about what kind of technician you are. Other telling signs are how you approach safety; your own and that of your assistant. How meticulous are you in collecting and analyzing data? What condition is your equipment in?

    When we look at the in-field work area, how do you post or identify what work is being done and what restrictions apply to the immediate are? At most facilities, the safety department has already determined how this is to be done. If this task has not been completed at your work site, there are guides that can help you determine the restrictions and the standoff distances required. The most important of these guides is NFPA 70E. Within this document are PPE and necessary qualification guidelines, along with different approach distances depending on the type of equipment being inspected. Being familiar with these requirements along with implementing and enforcing them is crucial to workplace safety; not just for you, but for all those around you.

    Another question to consider is: how do we keep unnecessary personnel out of our work area? After all, we don’t need any spectators and if there isn’t a valid reason for a person to be in your work area, they shouldn’t be there. When determining what type of barriers to use and where to place them, we can refer again to NFPA 70E where you will find recommendations for barricade types and required distances. Generally speaking, the barriers should keep unprotected (no proper PPE) people far enough away that they will be safe from injury in the case of an incident. The barricade should be recognized throughout the facility something to NOT cross under any condition without proper clearance from you. Danger tape with proper signage clearly stating what the hazard is and who can authorize entry is necessary. Each facility has their own version of this type of barrier, but if you work at a facility that does not, you should develop one in conjunction with the safety department.

    Keeping a neat, orderly work area not only makes it easier for you to find tools and equipment, it’s safer. If things are scattered all over the floor, you’ve just created a number of trip hazards. If equipment is piled haphazardly it can fall over into energized or rotating equipment.

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    8 Steps for Gathering Effective Motor Testing Data - Part One
    Motor Talk

    It is estimated that almost half (45%) of global electricity is used by electric motors. Electric motors drive all parts of many industries, from power generation to water and food supply to consumer products. The importance of electric motors in modern society cannot be under- stated. It is because of this large role that it pays huge dividends to keep our electric motors running efficiently through a quality reliability program that includes Electric Motor Testing (EMT) and Motor Circuit Analysis (MCA).

    Electric motor test instruments have become extremely effective reliability and diagnostic tools for motor and motor circuit testing. Significant improvements in motor longevity and overall plant reliability may be achieved through proper implementation of this established technology. But, as with any new program there will be growing pains. These will start immediately upon receipt of your test equipment. Who should conduct the testing? When should testing be conducted? Do we have procedures in place? If not, what procedures need to be developed? What should be tested? The following paper provides eight steps that, if followed, will enable successful and effective electric motor testing data for your reliability program.

    Step 1 - Personnel Preparation

    As with any endeavor, the key to success is knowledge of the task to be performed. With motor testing this means a thorough understanding of the equipment to be used including test capabilities, diagnostic strengths/weaknesses, and in-depth knowledge of the equipment to be tested.

    Equipment capability information is usually provided by the motor tester manufacturer through initial training. A comprehensive knowledge of motor operation and failure modes is also necessary, but it’s not something easily obtained and is rarely provided by the test equipment manufacturers. Apprentice training, experience and specialized training are the most effective means of gaining the necessary knowledge.

    Developing proficiency is another challenge. This where we don’t want to learn by our mistakes. Making erroneous calls and missing significant problems will detract from the credibility of the equipment, the technician, and the reliability program. Most industrial facilities have spare motors on hand, so when first starting to test, test warehouse spares, then expand to acceptance testing. This will provide you with time to learn software, test capabilities and develop the proficiency to test operational motors with competence and expedience.

    Step 2 - Preparation for Equipment to be Tested

    What equipment should be tested? Perspectives can vary widely in answer to this question. Criticality is in the eye of the functionary at your facility. What is critical to production may not be as critical to the maintenance or safety departments. The best way to address criticality is from four basic perspectives; operational, safety, logistical, and environmental.

    Operational Criticality is straightforward and is based primarily on operating voltage:

    1. Medium / high voltage / frequent starts
    2. Medium / high voltage
    3. Low voltage / frequent starts / high horsepower
    4. Low voltage / high horsepower
    5. Critical VFD powered motors
    6. Non-redundant critical motors

    Medium and high voltage equipment will cost significantly more to repair or replace and may require prolonged lead time for replacement. Frequent starts, at any voltage, will fail more frequently than motors that run continuously or start infrequently. Motors that are driven from VFD’s normally run hotter and are subject to more rapid thermal degradation of the insulation. Some motors of fractional horsepower may be critical, i.e. a ¼ HP lube oil pump for a 6000 HP sleeve bearing motor may be as critical as the 6000 HP motor.

    Safety Criticality is simple and straightforward as well. Can someone be killed or injured if this equipment fails?

    Logistical Criticality is based upon availability of repair facilities and replacement parts. In this world economy, parts may have to be manufactured halfway around the globe. This entails a prolonged downtime for the failed equipment and a possible significant effect on the process.

    Environmental Criticality is, again, straightforward; will failure of this equipment cause environmental damage such as a toxic effluent release or excessive air pollution?

    Get all of the key players involved to determine criticality of equipment. Sit down and discuss priorities, maintenance difficulties, safety, and logistical issues and come up with a list of critical assets. Once an equipment list is developed it should be organized into routes. Plan so that a maximum number of assets can be availed in each location. Jumping around reduces productivity. Routes should have a recurring periodicity based on criticality.

    Next month we will cover some additional steps to follow to help you establish and maintain a successful and effective electric motor program by getting reliable testing data.

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    8 Steps for Gathering Effective Motor Testing Data - Part One
    Motor Talk

    In last month’s posting, we briefly discussed about the importance of motors and motor testing. We also deliberated about the first step to take—personal preparation—and how they should understand the tester equipment, motor operation, and developing proficiency in testing. We then turned our attention to the second step—preparation for equipment to be tested—and criticality of equipment from multiple perspectives; operational, safety, logistical and environmental.

    This month, we discuss the next three steps to take to gathering effective electrical motor data.

    Step 3 – Preparation of Test Equipment

    In order to perform motor testing effectively, the test equipment should be in optimal condition. The tester should be in calibration with the most recent updates to the operating software (Note: when updating software be aware of possible compatibility issues. New software updates should clearly explain any operating systems (OS) that are and are not supported.) Software upgrades are essential. Many times they correct inaccuracies or provide important safety procedures or steps. The associated equipage should be inspected and tested, as applicable, to prevent problems when in the field conducting tests. Conduct a check of the equipment the day before testing is scheduled. A simple generic checklist will help with the readiness of the equipment:

    Checklist for Effective Testing:

    • All batteries operable and charged
    • Deep cycle batteries as required
    • Test leads are free of any nicks or cuts in the insulation
    • Voltage clips or test clips are clean and free of any foreign debris or corrosion
    • Voltage clips or test clips are snuggly threaded or make a tight fit on test leads
    • Current probes have good batteries (if applicable)
    • Inspect power cords for nicks and breaks in the insulation
    • Current probes jaws are clean and free of any foreign debris at both the top and hinge point
    • Current probe spring tension is good
    • Test lead connection points on the test instrument are clean and free of dust and foreign debris
    • All electrical and data port cables on your test instrument are properly connected.

    Step 4 – Check Operational Status of the Tester

    Prior to acquisition of any test data, a quick operational test of the motor test instrument should be conducted. Use of a small test motor or stator will verify that the de-energized test data acquired, is accurate or repeat- able.

    To verify accurate energized data, perform a quick power quality test. Place all current probes on one phase cable and run the test. Compare bus phase voltages to acquired voltages and all of the amperage readings should be the same. Once you feel comfortable that you are collecting reliable data, begin your testing route.

    Step 5 – Maximize the Amount of Circuit Under Test (and the Amount of Load on the Circuit)

    If you are devoting the time to conduct testing, you should test as much of the circuit as possible.

    De-energized testing is usually conducted downstream of the de-energized contactor. With de-energized testing, connections made upstream will identify circuit anomalies between the connection point and the motor. Once identified, circuit isolation can be conducted and the source localized.

    8 Steps for Gathering Effective Motor Testing Data - Part Two 1

    Energized testing should be performed from the starter cabinet, connections should provide at least one local level of circuit protection above the point of connection, i.e. connect on the load side of the main breaker or load side of the fuses. Energized testing can be used to observe voltage and current FFT data to isolate spectral peak sources from upstream or downstream of the test connection point.

    8 Steps for Gathering Effective Motor Testing Data - Part Two 2

    Step 6 – Verify or Confirm Identified Anomalies

    When a potential problem is identified, it is just that; a potential problem. You should take steps to validate that it is, in fact, a problem. Sometimes erroneous data or unique characteristics of the equipment under test may give indications of a fault. You should perform all possible equipment checks and run additional correlative tests to validate your indications. Let’s say, for example, your test data indicates a possible high resistance connection.

    Check your test lead connections and re-run the resistance tests. If you get a current unbalance, check equipment loading to ensure that the unbalance is not due to insufficient loading. If load is sufficient save the data and run a quick power quality test, with all the current probes on one phase, to make sure that you do not have a defective probe. If you have Fpp (Field Pole Pass Frequency Sidebands) sidebands indicating possible rotor bar anomalies, check for swirl effect, current modulation, increased current draw for a given load and reduced

    in-rush current with longer start duration. These simple checks and correlative measures, can prevent erroneous data leading to bad calls, which can cast doubt on either you, the technology, or both.

    Next month, the last two steps will be examined.

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    8 Steps for Gathering Effective Motor Testing Data - Part One
    Motor Talk

    The past two month’s postings have revolved around what it takes to get good, effective motor testing data. The first month we examined personal preparation and preparation for equipment to be tested. Last month we discussed preparation of the test equipment, checking the operational status of the tester, maximizing the amount of circuit under test, and finally, verifying or confirming identified anomalies.

    In this last installment, we examine the last two steps to gathering effective electrical motor data.

    Step 7 – When Possible, Correlate with Other Technologies

    8 Steps for Effective Motor Testing DataWhen possible, you should correlate acquired data with other technologies. This will help confirm the existence of a problem and help quantify the severity. Sometimes reliability technicians tend to try and be a “one-man band.” But working together as a “RELIABILITY GROUP” will yield immeasurable results. Reliability technologies are like a set of wrenches or sockets, they all have specific purposes, but overlap.

    When they are used together you can work on most anything. The same with the reliability technologies; when used together you can diagnose most any problem. Proper use of vibration, ultrasound (shown in image), oil analysis, infrared and electric motor testing can provide a maintenance environment that will have minimal undiagnosed failures, resulting in maximum productivity and/or reliability.

    Step 8 – Generate Effective Reports (Communication)

    Believe it or not, reporting is probably the most important aspect of an effective motor testing program. The report is your deliverable. It can be the basis on how you are judged as a motor test technician. If you are a service oriented company, you already know or should know this. “In house” programs tend to sometimes neglect or minimize reporting which works to the overall detriment of the program. Budget expenditures are based on perceived value of the desired item. If your motor testing program does not appear effective, you may not be receiving the funding level you may require.

    Not only do you have to generate effective reports on identified anomalies, you need to generate updated reports on the overall success of the program. Work with management to establish performance metrics or KPIs. Bar graphs showing the number of identified and corrected anomalies should be posted in high visibility venues. Display monthly and yearly discrepancy counts, hopefully it shows a marked decrease. Display the budget reductions for motor rewind and replacement or the number of rejected motors not put into service that may have failed prematurely. Specific examples will help you illustrate your point. Use the data you gather not only to identify and repair problems, but also to demonstrate the effectiveness of the program.

    Communication, in addition to effective reports, is key to program success. You should have a network of communication established between yourself to middle and upper management, maintenance and production departments, as well as the other PdM technology personnel.

    Communications with planning, safety and logistics are also important departments for procedural and material support. Integrate your EMT results into the site EAM (Enterprise Asset Management) reporting to further support these types of communication. Other areas of important communications are with the motor shops, motor manufacturers, the tester manufacturer and your EMT knowledge provider.

    An effective motor testing program should be part of an effective reliability program. Use of the above 8 steps will provide your program with a significant and highly effective tool as part of a “World Class” maintenance program.

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    Getting There With What You Need
    Motor Talk

    Today’s motor testers challenge the term “field portability,” in particular the de-energized test instruments.  The power supplies necessary to provide the high insulation test voltages are the main reason.  Expedient testing can be hampered by not carrying the necessary tools with you to handle the majority of the circuits and tests to be performed. 

    So, let’s build the ultimate “Motor Testing Tool Kit.” The most important component of this kit is a means of carrying the test instrument(s), the necessary gear, and tools to support testing.  Utility carts are fine, but-limited in mobility. Moving them over rough surfaces and going up a set of stairs can be cumbersome at best. 

    What I found, quite by accident, was a tool cart.  Years ago I was doing motor testing at a new customer site, a paper mill.  Their insurance company mandate was that there would be nothing in electrical equipment rooms except equipment.  Back in those days, I would carry an accessory bag and my tester.  When in an equipment room I would improvise and set my tester on a box, trash can, bucket….whatever I could find as a “desk-like” substitute to hold my tester.  Well, on this job I spent all of my time kneeling on a concrete floor, running my motor tests.  Needless to say, my first stop after returning home was a place to find a cart.  All I wanted was a two shelf cart on castors, preferably plastic, and narrow enough to lay under my Tonneau cover in my pickup bed for transport.  Simple enough, right?!

     I went everywhere and no one had what I needed.  On a whim I went into Lowes and asked a sales assistant where the utility carts where.  He guided me to an isle and I didn’t see what I wanted but what I did see revolutionized my testing methodology from that time on. It was a two-wheel tool cart made of heavy plastic with a hinged lid and a retractable handle to pull it with. It wasn’t what I wanted, but it was exactly what I needed! I immediately went about making modifications to enhance the cart’s usefulness.  It was the size of a large cooler and easily held all of my gear. However, it didn’t have dividers and when I would take my tester out; everything would fall to the bottom. I found some old arc shoots from a 4160V starter and box cut them so that I would have 4 compartments inside the cart. I used Velcro to hold them in place. I then cut up an old tool bag and riveted it to the dividers in sections.  The individual pouches gave me numerous storage slots. I added an extension cord reel carriage, bolted to the non-handle end and aligned with the cart hand grip, and I was almost there. I put Velcro on the top of the cart, and bottom of my tester, and Voila – a Motor Testing Tool Cart.

    Now, what to put in there? 

    (Besides the test instrument/s batteries, chargers, test leads, amp probes and PPE):

    • Multimeter and test leads
    • Spot Radiometer
    • Digital Level and/or Inclinometer – for shaft position indication
    • Machinist’s “V” Block magnetic base –for mounting inclinometer or level on motor shaft
    • Electrical tape -- for phase labeling
    • Wire labels – for lead removal identification
    • Soft Wire Brush – for cleaning leads and terminals
    • Strobe Tachometer
    • Lockout Tagout materials
    • Three to one jumper – for Wye Delta starters
    • Miscellaneous jumpers – as needed
    • Fuse pullers
    • Screwdrivers – Phillips and Standard, popular sizes or an “all in one.”
    • Sockets, Wrenches and Ratchets – for lead removal and re-installation as necessary
    • Diagonal, needle-nose pliers, channel locks
    • Solder and Soldering iron
    • Flashlight
    • Rags
    • Clipboard, paper, pens, pencils, discrepancy labels
    • Mili-Gauss meter – for flux measurement, particularly on Field Poles)
    • Reference Materials: NEMA Pocket Engineering Handbook, Ugly’s Electrical Reference, Torque Specification Chart, etc. I also carry a pocket Vibration reference manual.
    • Tie Wraps – various sizes
    • Extra batteries (for flashlight, spot radiometer, amp probes – as applicable
    • Folding Chair (sits nicely diagonally across the top of the box

    What’s in your Motor Testing Tool Box?

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