Engineering guide
How to Specify an Electrically Insulated Bearing
Electrical isolation is an equipment-level decision. A coating description or base bearing number alone does not establish the correct insulated bearing for a motor or generator.
People and industrial backgrounds are application illustrations; product photography and specifications are identified separately.01
Start with the current path and bearing position
Identify the motor or generator, drive arrangement and the bearing position being replaced. State whether the existing design isolates one bearing position, both positions or another component. This helps engineering understand the intended current path instead of assuming that every bearing needs the same construction.
02
Confirm the complete designation and envelope
Record every character from the existing bearing and provide clear photographs where possible. Confirm shaft diameter d, housing diameter D and available width B. Suffixes can describe clearance, cage, seals, pairing or a special design; do not remove them during an initial match.
- Complete bearing marking and manufacturer reference
- Shaft, housing and width dimensions
- Motor frame, power and drive information
- Fixed or floating bearing position
03
Describe the mechanical duty
Provide normal and maximum speed, radial and axial loads, start-stop frequency, vibration and expected service interval. Electrical isolation does not remove the need to verify the bearing's mechanical suitability.
04
Define lubrication and environment
State the lubricant, relubrication method, operating temperature, contamination and sealing arrangement. The final proposal should be confirmed against the complete equipment duty before quotation or installation.
Frequently asked questions
Final checks before inquiry
Can a standard bearing number identify the insulation design?
No. The base number helps identify envelope and bearing type, while the insulation location, construction and performance require the complete suffix and application data.
Should both motor bearings be insulated?
Not automatically. The intended current path and equipment arrangement must be reviewed before selecting the insulated position.
What should be attached to an inquiry?
Attach marking photographs, the motor nameplate, a bearing arrangement drawing and any available shaft or housing dimensions.