Addressing Electrical Erosion in Bearings

Electrical erosion, also known as electrical pitting or fluting, is a significant issue in bearings exposed to electrical currents. This blog examines the causes, effects, and preventive measures for electrical erosion in bearings.

Causes of Electrical Erosion:

1. Electrical Discharge: When an electrical current passes through the bearing, it can create sparks that cause localized melting and pitting on the bearing surfaces.
2. Potential Difference: A potential difference between the bearing components can lead to electrical discharge, especially in applications with variable frequency drives (VFDs).
3. Improper Grounding: Inadequate grounding of the machinery can result in stray currents passing through the bearing, causing electrical erosion.

Effects of Electrical Erosion:

1. Surface Damage: Electrical erosion causes pits and grooves on the bearing surfaces, leading to increased friction and wear.
2. Increased Vibration: The irregular surfaces created by electrical erosion result in increased vibration and noise during operation.
3. Reduced Load Capacity: The structural integrity of the bearing is compromised, reducing its load-carrying capacity.
4. Premature Failure: Continuous exposure to electrical erosion can lead to premature bearing failure, necessitating frequent replacements and increasing maintenance costs.

Preventive Measures:

1. Proper Grounding: Ensuring that all machinery components are properly grounded can prevent stray currents from passing through the bearing.
2. Insulated Bearings: Using insulated bearings or bearings with ceramic rolling elements can prevent electrical currents from passing through the bearing.
3. Shielding and Filtering: Implementing electrical shielding and filtering in the machinery can reduce the risk of electrical discharge.
4. Regular Inspections: Conducting regular inspections and monitoring for signs of electrical erosion can help in early detection and intervention.

Case Study: A bearing in an industrial motor exhibited signs of electrical erosion, with noticeable pitting and increased vibration. The motor operated with a variable frequency drive (VFD), which contributed to the electrical discharge.

Solution:

1. Grounding: The motor and associated components were properly grounded to prevent stray currents.
2. Insulated Bearings: Insulated bearings were installed to prevent electrical currents from passing through the bearing.
3. Shielding: Electrical shielding was implemented to reduce the risk of electrical discharge.
4. Monitoring: Regular inspections and vibration monitoring were conducted to detect early signs of electrical erosion.

By implementing these measures, the incidence of electrical erosion was significantly reduced, improving the bearing’s performance and extending its operational life.