Current-Insulated Bearings
Protect Your System with Current-Insulated Bearings
Regardless of whether electric motors or generators are used in the rail sector, wind power sector, or in industrial applications, the passage of current poses a risk to rolling bearings in many applications. In unfavorable conditions, this causes damage to raceways and rolling elements and leads to quicker lubricant degradation and thus to premature, unexpected failure of a motor or generator. Depending on the structure of the system, driven units can also be affected by the passage of current.
As a leading provider of bearing solutions, we can offer you extensive expertise and a broad product range of current-insulated bearing solutions. Learn more about our new coated Insutect A bearings and our hybrid bearings.
Passage of Current in Bearings
How damage is caused by the passage of current
In recent years, the use of frequency converters has become increasingly important in industry. This is due to the numerous benefits, such as more precise control of the motor speed of electric drives, improved energy efficiency, and increased productivity.
However, frequency converters often generate parasitic currents in the motor, which can also flow through the rolling bearings. If an electrical voltage is applied to a rolling bearing between the outer and inner ring, this can result in the passage of current and cause damage to the lubricants or lubricating greases, rolling elements, and raceways.
The use of current-insulated bearings can prevent the premature failure of electric drives, thereby avoiding the repair measures and costs associated with production downtime.
Current-Insulated Bearing Solutions
How to avoid damage in the future
In general, completely eliminating the causes of electrical stresses on rolling bearings proves to be difficult. Nevertheless, it is possible to avoid bearing damage if the passage of current can be significantly reduced or prevented. To protect against parasitic currents, Schaeffler offers rolling bearings with an aluminum oxide coating (J20G series) and hybrid bearings with ceramic rolling elements – identifiable by the HC prefix – in its product portfolio. Find the perfect solution for your application.
Coated Insutect A bearings
Insutect A bearings provide a high level of electrical insulation protection. The outside surface of the outer and inner ring is coated with an insulated aluminum oxide foam, which is applied by plasma spraying. For many applications, bearings with the Insutect A current-insulating coating are the most economical solution.
Hybrid bearings
Schaeffler recommends hybrid bearings (HC prefix) for applications exposed to particularly high electrical loads. Due to their ceramic rolling elements, they offer the best possible protection against the passage of current.
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General Recommendation for Using Our Current-Insulated Bearings
Just the right bearing for your application
Which rolling bearing is right for an application depends on various factors. To reliably prevent damage caused by the passage of current, it is necessary to understand the entire electrical system, and the grounding system, current conduction, and bearing insulation must be perfectly compatible with each other. With rolling bearings, the following recommendation generally holds true:
| Rolling bearing size (outside diameter) |
Standard applications (e.g., industrial electric motor) |
Applications with increased demands (e.g., traction motor for rail vehicles, generator for wind turbines) |
|---|---|---|
| < 120 mm |
Hybrid bearings |
Hybrid bearings |
| 120 mm - 240 mm |
Insutect A J20GA |
Insutect A J20GB |
| > 240 mm |
Insutect A J20GI |
Insutect A J20GB, J20GI Additional solutions on request |
