Diagnosing motors with the push of a button
MRO MagazineMachinery and Equipment Maintenance
The electronic devices used to test and analyze electric motors and other equipment have become much more powerful than in the past. Yet, in many instances these sophisticated devices have also introduced a high degree of complexity for users,...
The electronic devices used to test and analyze electric motors and other equipment have become much more powerful than in the past. Yet, in many instances these sophisticated devices have also introduced a high degree of complexity for users, requiring that highly trained and experienced personnel perform the testing.
Many of today’s devices are feature rich and capable of measuring and analyzing many factors, including surge comparisons, resistance, impedance and more. Unfortunately, not all of these potent systems are very user-friendly, and some require a substantial investment.
“Today, you can spend up to $100,000 on a winding analyzer,” says Mark Peden, president of Alliance Pump and Mechanical Service, Independence, MO, “but at the same time you could find a very robust model at a much lower price.”
Peden, whose company services utilities – including water and wastewater treatment plants as well as municipal, commercial and industrial pumping equipment – elected to do the latter, investing in a powerful portable winding analyzer and motor tester. Not only was the price in the lower range, but also the system was easy enough to use that highly trained specialists were not required to operate it.
“We’re a motor shop, which means we clean motors and install or service windings,” Peden explains. “We use an electronic analyzer to test the integrity of the motor windings, to ensure that they are going to provide our customers with dependable performance.”
The motors that Alliance Pump and Mechanical Service worked on have sometimes been subjected to harsh conditions, including excessive heat, debris, or occasional lightning strikes, all of which mean that windings have to be replaced. When a damaged or simply worn out pump and motor assembly arrives at the shop, Alliance technicians disassemble and thoroughly inspect the motor. The windings are then cleaned, baked and surge tested to make sure they are good.
“We have to be certain that the windings are good, or six months later a motor could fail, and due to the comprehensive warranty we provide, we’d end up eating the cost of repairing the unit,” Peden explains.
Peden says it takes a good analyzer to do a thorough test on the windings to make sure that the integrity of the motor windings is good. “I looked at several different models, and decided that the iTIG II looked like a pretty user-friendly unit that [produced] all of the tests and reports that we needed.”
The iTIG II is a winding analyzer and motor tester from Electrom Instruments, Longmont, CO, that comes with varying options and output ranges from 4 kV to 12 kV. By adding Power Packs, one can go to even higher voltages.
Peden adds that using this winding analyzer and motor tester is like an insurance policy.
“Once we’ve run the analyzer and everything passes, there is no doubt that the motor is good. And it also assures the customer that we did comprehensive testing, and that everything checked out,” Peden says. “After the testing, the device gives us a printable report that we provide to our customer as documentation of what we found. It’s part of the procedure we follow in motor repair.”
Power plant applications
Clark Myers, an electrician at Twin Oaks Power, L.P., Bremond, TX, a division of Optim Energy LLC, has been using Electrom winding analyzers for several years at the coal-fired power generation plant.
The testers use high-frequency 60 Hz surge pulses, eliminating ionization dissipation and thus better simulating what motors are subject to during operation.
“This is really the only testing and analyzing device we use for checking motors,” Myers says. “We also use it on the back of switchgear to ensure proper protection of the motor and the line. Typically this testing is done during a scheduled outage.”
Myers, a 35-year veteran of power plant construction and operation, adds that the iTIG is quite user friendly, and does not require engineering expertise or extensive training to operate it successfully.
“I’m not what you would call an expert as far as instrumentation is concerned,” he says. “This particular instrument is pretty straightforward. Basically, the company just showed us how to use the device, and ever since it has been pretty much second nature.”
Friendly but powerful
One of the big advantages of some of today’s most advanced instruments is that they are both easy to operate and interpret, but also contain powerful features.
The iTIG II that Alliance Pump and Mechanical Service purchased gives users the ability to perform a variety of tests from the most simple low-resistance tests to Megohm (also called insulation resistance), Hipot and advanced surge testing.
One of the key advantages of all iTIG models is that they use a 60-Hz surge pulse frequency, the same frequency at which most motors operate. This high pulse rate provides a sufficient frequency to overcome ionization dissipation and can thus isolate insulation weaknesses with more sensitivity, predicting future faults before low-frequency testers can, and it also better simulates motor operating conditions.
One of the most significant ease-of-use features is that the iTIG II enables users to enter the surge test voltage, push a button, and let the machine run the test independently. Surge waveform ranges are automatically set for all models, which eliminates the need to specify configurations, push multiple buttons, or turn dials.
All tests can be done with one instrument; they are available in manual to fully automatic models. No additional items are required other than accessories, which can be added on at any time. Tests that can be performed on this system include Surge Comparison, DC Hipot, Step Voltage, Insulation Resistance (Meg test), Dielectric Absorption (DAR), Polarization Index (PI), Low resistance (Ohms), Impedance (Z), Phase Angle, Inductance (L) and Capacitance (C). Models have different features included and all can be upgraded to any higher-level model.
A pioneer in the industry, Electrom Instruments started manufacturing surge testers in the 1980’s and produced the first digital winding analyzer in the early ‘90s, revolutionizing the motor testing industry. Today computers and software contribute to a greater level of instrument performance, flexibility, and ease of use.
For more information, contact Electrom Instruments at firstname.lastname@example.org or visit electrominst.com.