How to choose a suitable insulated bearing?

Note: When selecting an insulated bearing, one should not solely rely on the model suffix. It is necessary to make a comprehensive judgment based on the motor power supply method, shaft current type, installation structure, and on-site environment. Choosing the wrong type can easily lead to premature insulation failure and electrical corrosion faults.
First, distinguish between motor power supply and inverter operating conditions. ● For ordinary IGBT inverters with conventional carrier frequencies, the shaft current is mainly in the form of circulating current to ground, and coated insulated bearings are preferred; ● For SiC high-frequency carrier inverters with high high-frequency pulse voltage and prominent capacitive coupling current, hybrid ceramic bearings are preferred; ● For motors driven by mains frequency without inverter, insulated bearings are generally not required.
Determine the rotating structure and ascertain whether it is the inner or outer ring that requires insulation
● Most motors: The outer ring is fixed to the end cap, while the inner ring rotates with the shaft → Insulated bearings with outer ring (such as VL0241 and J20AA) are preferred and are the most commonly used type on site;
● Special structure: inner ring fixed, outer ring rotating (partial traction, wind power equipment) → select inner ring insulated bearings (VL2071, J20C);
Generally, an insulated bearing is only arranged at the non-drive end of the same motor, as insulating both ends simultaneously may easily induce new potential issues.
Select the model according to environmental conditions
● Indoor dry and standardized assembly conditions: alumina-coated insulated bearings offer the best cost-performance ratio;
● High humidity, salt spray, outdoor exposure, and large temperature differences (such as in wind power applications): The coating is more susceptible to moisture degradation, so it is preferable to use thicker coatings or directly opt for hybrid ceramic bearings;
● Working conditions with impact loads: Carefully select hybrid ceramic bearings, as ceramic rolling elements are prone to fracturing under impact. Thickened outer ring coating insulated bearings can be used as an alternative.

Combine operation and maintenance with cost factors
● Easy maintenance, simple spare parts replacement, and limited budget: outer ring coated insulated bearings;
● Large downtime losses, high maintenance difficulty, and requirement for long-cycle maintenance-free: choose hybrid ceramic insulated bearings;
● Note: The insulated bearing itself cannot withstand high current impact, so isolation and protection measures must be taken during welding operations and electrostatic discharge.
🔴 Selection Summary: For conventional variable frequency industrial motors with an outer ring fixed structure, priority should be given to outer ring coated insulated bearings; for high-frequency SiC variable frequency and field equipment that are difficult to maintain, hybrid ceramic bearings should be selected; only for special models with rotating outer rings, inner ring insulated bearings should be considered.