By Jacob Beck
With advanced, user-friendly surge testers and windings analyzers, motor diagnostics can now be performed at the push of a button. The electronic devices used to test and analyze electric motors and other equipment have become much more powerful than in the past. In many instances, however, these sophisticated devices have also introduced a high degree of complexity for users, requiring highly trained and experienced personnel perform the testing.
Many devices are feature rich and capable of measuring and analyzing numerous factors, including surge comparisons, resistance, impedance and more. Unfortunately, not all of these systems are user friendly, and some require a substantial investment-with costs going as high as $100,000 for a winding analyzer, which also can be complex and require highly trained personnel to operate and interpret.
Hydroelectric plants, coal-fired power generation plants and other power generation facilities require accurate motor testing. For municipal, commercial and industrial generation and pumping equipment, a powerful portable winding analyzer and motor tester that is considerably lower in price, and is easy enough to use that highly trained specialists are not required to operate it, can be an advantage.
For utility maintenance staff and motor shops-who all clean motors and install or service windings, an electronic analyzer is used to test the integrity of the motor windings to ensure they will provide dependable performance.
Motors are often subjected to harsh conditions, including excessive heat, debris or occasional lightning strikes, all of which mean windings have to be replaced. When a damaged or worn out pump and motor assembly is to be serviced, technicians disassemble and thoroughly inspect the motor. Windings are then cleaned, baked and surge tested to ensure they are good. At this time, it is critical to be certain all windings are good-or six months later a motor could fail.
It requires a good analyzer to do a thorough test on the windings to ensure they are sound. A unit that is user-friendly and can perform all needed tests is ideal, with varying options and output ranges from 4 kV to 12 kV, that could go to higher voltages by adding power packs.
Using a reliable winding analyzer and motor tester is like an insurance policy-once a technician has run the tests and everything has passed, there is no doubt the motor is good. After completing the tests, a good unit should be able to produce a printable report that can be used as documentation of what was found on the tests.
|The Electrom testers use high-frequency 60 Hz surge pulses, eliminating ionization dissipation and thus better simulating what motors are subject to during operation.|
Power Plant Applications
From coal-fired power generation plants to hydroelectric plants and other power generation facilities, motor testers are a vital component for repair and preventative maintenance of motors. Testers must be able to simulate or exceed usage conditions and parameters for accurate preventative forecasts.
Clark Myers, an electrician at Twin Oaks Power, L.P. (Bremond, Texas), a division of Optim Energy LLC, has used Electrom winding analyzers for several years at the coal-fired power generation plant.
The Electrom testers use high-frequency 60 Hz surge pulses, eliminating ionization dissipation and therefore better simulating what motors are subject to during operation.
"This is really the only testing and analyzing device we use for checking motors," Myers said. "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, added that the iTIG is 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," Myers said. "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."
|The iTIG II is a winding analyzer and motor tester from Electrom Instruments that comes with varying options and output ranges from 4 kV to 12 kV, or even higher voltages with the addition of Power Packs.|
Friendly but Powerful
One of the advantages of some advanced instruments is that they are easy to operate and interpret, but also contain powerful features.
The iTIG II 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 advantages of all iTIG models is that they use a 60 Hz surge pulse frequency, the same frequency as most motors operate. This high pulse rate provides a sufficient frequency to overcome ionization dissipation and can isolate insulation weaknesses with more sensitivity, predicting future faults before low frequency testers, and also better simulates motor operating conditions.
One of the most significant 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, which is available in manual and fully automatic models. No additional items are required other than accessories, which can be added at any time. Tests that can be performed 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). Various instrument models offer different features, but all are capable of being upgraded to any higher-level model.
About the author: Jacob Beck of Electrom Instruments is the developer of the iTIG II, an easy-to-use winding analyzer and motor tester with varying output ranges from 4 kV to 12 kV or higher that use high-frequency 60 Hz surge pulses-eliminating ionization dissipation and better simulating motors operating conditions-and allows users to perform low resistance, Megohm, Hipot and advanced surge testing. For more information, please contact Beck at email@example.com or visit http://www.electrominst.com.