Ernesto J. Wiedenbrug, Ph.D., SM IEEE
Some squirrel-cage motors designed for high start-up torque may get weaker over time, needing longer startup times and may perhaps even trip during line-start – but never show big problems in vibration or MCSA. This paper explains what gives high startup torque motors their special capabilities, describes a common failure mode making it nearly impossible to find the issue using MCSA or vibration, and diagnostic alternatives for these problems.
To continue reading the full case study, with images, please download the free PDF file here. http://csaanalysis.com/PDFS/Advanced%20Rotorbar%20Analysis%20-%20False%20Negatives%20-%20Dual%20Cage%20Rotors.pdf
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