Shaft current leads to rapid rolling bearing damage

Shaft current lead to rolling bearing damage 2020 - fast 06 - 05 some group cement service company using portable vibration spectrum analyzer of a cement factory key kiln head EP routine vibration monitoring and diagnosis of fan. From all the the vibration measuring point vibration velocity values of equipment is not large, fan maximum coupling end bearing level to 2. 55mm/s。 But on both sides of the motor and fan coupling lateral bearing characterized by high values of demodulation, the need for further analysis. Spectrum analysis: analyzing fan coupling end bearing, bearing outer ring demodulation spectrum characteristic frequency BPFO significantly, demodulation value as high as 5. 7 GRMS, the diagram below. Velocity spectrum fault sideband bearing outer ring on both sides of 1215 hz, 1215 hz should be bearing natural frequency, natural frequency was impact roller, BPFO modulation. Acceleration spectrum frequency frequency BPFO sideband, also appeared a large number of outer ring defects are as follows. Motor drive side demodulation spectrum also show that the bearing outer ring defects, as follows. Conclusion and suggestion: judging the bearing outer ring serious wear and should be replaced as soon as possible. Motor side bearing vertical load bearing outer ring frequency, defects judgment for early wear, must strengthen the lubrication and follow up. Overhaul results: overhauling the fan coupling lateral bearing, outer ring has serious defects. Traces of damage for 'washboard form, general this kind of situation for the shaft current. The motor load side bearing unchecked. Machine bearing damage photos, double row spherical roller bearing discussion: fan bearing operation four months due to the damage of shaft current produce, understand the motor frequency conversion motor, easy to produce shaft voltage, the voltage breakdown bearing oil film, to a certain extent will generate shaft current, burning bearing raceway. It is recommended that increase the shaft grounding ( Brush) Circuit, to avoid subsequent damages to the bearings. The two motor bearing also need to pay close attention to its trends, repair replacement if necessary. Motor nameplate ( Source: poldi condition monitoring)