As an answer to either question, some contractors may simply change out the whole motor, thinking it’s better to do that rather than wait until the motor dies.
That can be an expensive option for the customer, though. Perhaps a better idea is to turn to technology for help. Vibration analysis, thermography, and oil analysis can all provide a better idea as to what’s going on with the motor. Unfortunately, that equipment and technology can be an expensive investment for the contractor.
Another alternative is to partner with someone who has already made that investment in the equipment — a predictive motor maintenance specialist. This person can come out on a regular basis and take a look at the motor(s).
By using the latest technology, he’ll be able to tell if it’s just a bad bearing in the motor, or if, indeed, the whole motor needs replacing. For building owners with a large investment in their equipment, this regular maintenance is imperative if they want to keep their systems running smoothly.
Who needs predictive maintenance?Regular maintenance is always an important item, and it always seems to be the first item to be set aside when the budget gets tight.
Deferred maintenance, of course, usually leads to bigger and more expensive problems down the road, which building owners don’t always see.
While it seems fairly obvious that regular maintenance can be a benefit to just about any building owner, a better way to show that benefit is to perform a criticality analysis: Just how critical is this piece of equipment? Does the customer have spares on hand? What happens if the chiller goes down? How fast will the building heat up? Will frozen foods be lost if the system is down?
Chuck Yung, technical support specialist, Electrical Apparatus Service Association (EASA), St. Louis, MO, says that customers need to consider just how critical their processes are in order to determine how often maintenance should be performed.
“If the motor can be easily changed, and if the ramifications of failure aren’t very extreme, then the motor may need to be looked at just once a year and lubricated.”
If it’s a critical application that will shut down a large system and create problems, then obviously it should be checked more frequently. Yung suggests that for these applications, a vibration analysis should be performed either monthly or every other month, and lubrication (if possible) should take place every six months.
“Of course the cost of the motor is a consideration, too. The more ex-pensive the motor, the more often you want to take care of it,” says Yung.
In addition to vibration analysis, there are also several different types of oil analysis, infrared thermography, and heat measurements that a specialist can perform to determine if there is a motor problem. Butch Waters, reliability engineer, Reliability Assessed Maintenance (RAM), Phoenix, AZ, says that all types of technology have to be used, or else it will leave gaps in the predictive maintenance program.
There are low-end vibration analyzers and infrared guns starting at around $150, that can give the contractor some idea as to whether or not there’s a problem with the motor. And don’t forget to ask the equipment operator. If he’s knowledgeable and skilled, he should be able to determine whether a motor is vibrating more than usual or sounding different.
Some predictive maintenance specialists can even trend the motor data on a computer. Then it’s possible to make the rounds with a small, handheld analyzer and check many different motors, store the data, download it into the computer, and look at the vibration spectrums.
“Then you can not only look at trending — how does the vibration compare to what it looked like six months ago — but also specific frequencies that identify specific problems,” says Yung.
Catch the problem earlyIf the contractor determines there’s a problem with the motor, then what? Often the choices have been to either replace the motor or leave it until it dies. Replacing it can be expensive, and leaving it until it breaks down can be more costly.
A third, often overlooked choice is to call in a motor specialist. Someone like Waters can come out to a site and use whatever technology is appropriate to determine the problem before it becomes a crisis.
“The goal is to be there when the bearings are first starting to fail. Then it’s possible to shut down the system at a noncritical time and put new bearings in, which will save the cost of a rewind. Just in that cost justification, you’ve usually always saved my cost,” he notes.
Waters adds that if a regular predictive maintenance program is in place, it will save building owners even more money, although they might not recognize that at first.
“Perhaps they’ll have to spend $300 to $1,000 a month in additional maintenance costs. However, instead of a $10,000 motor job, they’ll only have a $300 to $500 rebuild on the motor. That’s where the savings come in.”
And if there is a catastrophic failure of the motor, it can damage other equipment as well. “For want of a $15 bearing, the customer could literally be looking at tens of thousands of dollars worth of damage,” says Yung.
Besides reducing repair costs, probably the biggest benefit to performing routine predictive maintenance is reduced downtime. In the case of building owners, they face a smaller chance of having a motor fail in the middle of August, resulting in hot, irate tenants.
Waters notes that it can also reduce the maintenance budget by eliminating the need to keep all the spares in stock to use in case of a breakdown. Since the maintenance becomes planned, motors don’t need to be kept on hand for emergencies.
But for all the benefits, many contractors still don’t know about predictive motor maintenance specialists. Waters notes that many times the damage is already done to a motor by the time the contractor sees it.
However, “With a good predictive motor maintenance program in place — checking the motors, pumps, cooling towers, and chillers — the two of us working together can more than likely bring down the cost to the client.”
Sidebar: New technology is availableThe main technologies used in predictive motor maintenance are vibration analysis, thermography, and oil analysis. Now a fourth technology has made its debut: current analysis.
This technology looks at the phase sequence differences in monitoring the current — the amperage of the motor — on all three lines. Yung says it’s better able to trend winding faults and rotor bar discrepancies, the latter of which has been historically difficult to identify. “It’s a promising technology,” says Yung.
Current analyzers are available now, but they’re not as widely accepted (yet) as vibration analysis. “As more equipment becomes available and costs come down, we’ll see an increase in its use,” notes Yung.