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—with costs going as high as $100,000 for a winding analyzer, which also can be very complex and require highly trained personnel to operate and interpret.
For companies that service utilities, including water and wastewater treatment plants, as well as municipal, commercial and industrial pumping equipment, investing in a powerful portable winding analyzer and motor tester that is considerably lower in price, but also user-friendly and easy enough to use that highly trained specialists are not required to operate it can be a real boon.
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 that they will provide dependable performance.
Motors are often 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 is to be serviced, technicians disassemble and thoroughly inspect the motor. Windings are then cleaned, baked and surge tested to make sure they are good. At this time it is critical to be certain that 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 make sure that they are sound. A unit that is user-friendly and can perform all needed tests is ideal, with varying options and output ranges from 4kV to 12kV, that could go to even 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 that 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.
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.
The best testers use high-frequency 60Hz surge pulses that eliminate ionization dissipation and thus better simulate what motors are subject to during operation, and provide comprehensive tests, so can be used as the only testing and analyzing device for checking motors. The ideal tester can also be used on the back of switchgear to ensure proper protection of the motor and the line (typically this testing is done during a scheduled outage).
Such a device should be quite user friendly, and would not require engineering expertise or extensive training to operate successfully. Its use would be fairly straightforward, and users would find it second nature to operate.
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.
An ideal tester would give 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 such a unit is that it would use a 60 Hz surge pulse frequency, the same frequency as most motors operate at. 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, and also better simulates motor operating conditions.
Another characteristic of an ideal testing unit would be ease-of-use features, such that it would enable users to enter a surge test voltage, push a button, and let the machine run the test independently. Surge waveform ranges could be automatically set for all models, which would eliminate the need to specify configurations, push multiple buttons, or turn dials.
All tests should be able to be done with one instrument; and such an instrument should be available in manual and fully automatic models. No additional items would be required other than accessories, which could be added on at any time. Tests that should be able to be performed on such a 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). Various models of the instrument would generally have different features included, but all should be capable of being upgraded to any higher-level model.
For more information, contact Electrom Instruments, 1821 Lefthand Circle, Longmont, CO 80501; Phone: 800.833.1881 , 970.669.6609; email: firstname.lastname@example.org or visit the web site: http://www.electrominst.com