转子杆故障维护问题：振动传感器警报

A 398 kW medium-voltage motor exhibited strange behavior while operating a blower in a cement plant. Vibration equipment showed that the vibration amplitude increased over time. The maintenance team, unable to pinpoint the problem, continued running the motor until the bearings had to be replaced. This occurred several times without any remedial action or explanation for the bearing failure. On several occasions, the motor tripped upon startup. Beyond these symptoms, the recurring failures of the motor remained unexplained. The motor was used daily between the multiple bearing replacements.

The factory’s condition monitoring unit invoked Prescon to perform a condition assessment of the motor. Prescon used ESA (Electrical Characteristic Analysis) to evaluate the motor’s condition. A few minutes later, test results showed that cracks had appeared in the motor’s rotor rod/end ring.

Electrical characteristic analysis (ESA) is a power-on testing method that acquires voltage and current waveforms while the motor system is running to assess the health of the motor system. Power-on testing provides valuable information for AC induction and DC motors, generators, wound-rotor motors, synchronous motors, machine tool motors, and more.

Then the motor was turned off and on again. As shown in the image below, a crack was found on one of the end rings.

ESA technology enables users to test motors under load. The ALL-TEST Pro’s ESA technology combines two instruments in one: a complete motor analyzer (ESA) and a power quality analyzer (PQ). The on-state test (ESA mode) provides valuable motor health information for AC induction and DC motors, generators, wound-rotor motors, synchronous motors, machine tool motors, and more. In PQ mode, it can be used for energy data logging, harmonic analysis, voltage and current graphs, waveform viewing, capturing sags and dips, transients, and events.