Combinations of new and existing technology have changed the face of predictive maintenance.
For more than a decade, predictive maintenance (PdM) has enabled facilities technicians to identify and solve problems before they have a chance to damage equipment. Yet financial woes caused by the recent economic decline have taken less than a year to have a markedly negative effect on the discipline. Operations workers are under pressure to maximize profit in every way, leading to cramped equipment rooms, insufficient maintenance downtime, and inadequate infrastructure. These budgetary constraints have also helped to create an odd mix of overloaded equipment, lightly loaded equipment, and complicated switching.
Compressed schedules are allowing Code violations and workmanship problems to creep into new construction. Tight budgets sometimes preclude sound engineering, which usually precludes adequate testing. Increasingly, construction crews are supplied with inadequate training, tools, and documentation to conduct the required testing, all of which makes for a challenging maintenance environment. But new developments like improved test instruments, monitoring equipment, training, software, communications, and procedures can help.
Test instruments.
Advances in technology have made test instruments smaller and less expensive, placing a wider range of testing capabilities at a maintenance worker's disposal.
Today, rugged test equipment with selectable displays, easy-to-use scope functions, analysis, storage, and networking is readily available and affordable. This equipment goes beyond electrical properties to measure variables like temperature and vibration. Some of these devices store labeled profiles that include the settings you used in the past for tests on specific equipment. The instruments also make it easier to perform trending analysis.
As an example, under the old way of doing things, the current year's annual IR tests had no correlation to the previous year's IR tests — or any previous test. As long as a cable was in spec, it was considered OK. Although trending is equally important for preventing disasters and providing other benefits, spotting trends was difficult without easy methods for plotting data. No longer. Today, when your computerized maintenance management system (CMMS) issues a work order, it identifies the specific test, instrument, and settings to use for the piece of equipment in question. A technician performs the test with the same settings and procedure used the time before. After the test, the technician can download data to a system that aggregates data from previous tests and builds trend reports.
From the field, you can download directly to a laptop or PDA, or you can transmit wirelessly to a central unit. Wireless communications with a database allows for instant feedback and analysis against equipment history. Consider the following example. A technician calls up a trend report that demonstrates a slow deterioration of insulation resistance and a sudden, sharp turn upward. Perhaps an event like a voltage spike caused acute damage. This cable is destined to fail — even though it's in spec. So the technician identifies it with a tag and sends a work request to the central system. When the testing is complete, a coordinator views the work requests and schedules work orders for repairs during the next available window. It's the trend, not the raw measurement, that tells you what you need to know. Integration with a CMMS and other software systems allows you to tie information together from all of your communications-enabled test equipment.
If you can conduct a manual test like voltage measurement, the predictive portion of the job is what you do with the test results. And that's usually a matter of using predictive software or some other means of converting raw data to visibly obvious trends. This brings us to another facet of PdM — automatic monitoring and testing.
Monitoring equipment.
Just because you have the right test equipment, that doesn't mean you don't need monitors or vice-versa. Test equipment and monitoring devices serve different functions.
Consider batteries. Battery testing requires special training, entails special hazards, and generates costs not involved in other testing. As a result, most facilities limit costs by using longer battery testing intervals. In lieu of battery tests that could be spaced too far apart to catch problems in time, a battery monitor identifies possible problems — you can then perform manual tests to determine how best to preserve uptime. Similarly, a power monitor at a panel — be it the service entrance or the distribution for specific equipment — eliminates the need for a balancing act between testing frequency and downtime risk.
The same advances in test equipment have had a pronounced effect on the functionalities of monitoring equipment. From intelligent breakers to powerful panel meters, several choices in monitoring equipment exist for spotting nearly any problem before it occurs. Imagine having a protective relay that tells you the degree of contact erosion so you can schedule maintenance before a failure occurs. These capabilities exist today.
Communications tools and procedures.
PDAs, networks, wireless computers, and cell phones have all changed the face of PdM. (See “Remote Power Monitoring and Control” on page 16 of this issue for the latest in remote maintenance monitoring.) Communications tools enable you to do more than monitor from a distance. Thanks to all the data collection, trending, and analysis, equipment vendors have tremendous knowledge of how equipment actually performs — and fails — in the field.
Consequently, maintenance workers have changed their ideas of what constitutes effective maintenance. It's evident now that some of the time-honored practices were wrong and others aren't performed nearly enough. Debates used to rage about whether it made sense to retorque fasteners as part of PdM. Mechanical engineers said no, due to the risk of stretching the fastener beyond its elastic limits. Maintenance engineers said yes, because things vibrate loose. Analysis of industry data shows the mechanical engineers were right. Today's accurate, easy-to-use infrared thermometers allow you to identify loose fasteners and focus on only those that need immediate attention.
Just because the economy may not allow for it, predictive maintenance isn't an investment you can do without. Thanks to technological advances that have made test instruments smaller and more affordable, protecting your facility against failures and downtime is much more feasible. Not only will you be protecting your equipment, but you'll also be protecting your bottom line — and that's the best investment you can make.
Photo courtesy of Staco Electric.
