What is Electrically Insulated Bearings?

Electrically Insulated Bearing adopted special spraying process, the outer surface of the bearing is coated with high quality film,which has strong binding force with the substrate and good insulation performance.It can avoid the electric erosion of the bearing caused by the induced current, prevent the damage caused by the current to the grease, rolling body and raceway, and improve the service life of the bearing.

The process has been improved continuously. In the insulated bearing, there is a layer of 100μ m thick coating on the outer or inner ring surface, which can withstand the voltage of up to 1000 V DC. Special spraying process can form a coating with uniform thickness and strong adhesion,After further treatment, To protect it from moisture and humidity after further treatment.

Electrically Insulated Bearing can avoid the damage caused by electric corrosion, Therefore, compared with the common bearing, it can be used in the motor to ensure more reliable operation. Compared with other insulation methods, such as shaft or shell insulation, it is more cost-effective and reliable. The external dimensions and basic technical characteristics of insulated bearings are the same as those of uninsulated bearings, so they can be 100% interchanged. It is suitable for motors and generators, especially for variable frequency motors.


Electrically insulated bearing classification

Electric insulated deep groove ball bearing

Electric insulated angular contact ball bearing

Electrical insulated cylindrical roller bearing

Insulated bearing of inner or outer ring with oxide coating

Hybrid bearing with electrically insulated ceramic rolling element

Dimensional range of electrically insulated bearing

  1. Electrically insulated deep groove ball bearing

Internal diameter range: 40mm-140mm

Outer diameter range: 80mm ~ 300mm

Width dimension range: 18mm ~ 62mm


  1. Electrically insulated angular contact ball bearing

Internal diameter range: 40mm-140mm

Outer diameter range: 80mm ~ 300mm

Width dimension range: 18mm ~ 62mm


  1. Electrically insulated cylindrical roller bearing

Internal diameter range: 45mm-140mm

Outer diameter range: 100mm-300mm

Width dimension range: 25mm-62mm


Application of Electrically Insulated Bearing in motor

  1. The cause and harm of the formation of motor shaft voltage and bearing curren,In the operation of the motor, any unbalance in the stator and rotor magnetic circuit or the phase current around the shaft can produce the flux linkage of the rotating system, When the shaft rotates, these flux chains can produce potential difference at both ends of the shaft, This potential difference is called shaft voltage,The shaft voltage can excite the circulating current in the loop (closed circuit) formed by the shaft and the casing through the bearings at both ends, which is called the shaft current, In addition, there is a lot of residual magnetism in the rotor core. For wound rotor motors, if two or more winding points are short circuited to the rotor core or rotor shaft, shaft voltage and shaft current will also be generated.

The magnitude of the bearing current is related to the structure of the motor, the power of the motor, the amplitude of the driving voltage, the rise time of the pulse, the length of the cable, etc. The greater the power of the motor, the higher the driving voltage, the steeper the rising edge of the driving voltage and the shorter the cable, the greater the bearing current.

  1. Measures to block shaft current – using Electrically Insulated Bearing

In order to avoid the damage of the shaft current to the bearing, effective measures should be taken to isolate the shaft current. For large motors with independent bearing pedestals at both ends, isolation gaskets made of insulating materials can be placed between the bearing pedestals and metal pedestals. For the motor with ordinary bearing and shell assembled as a whole, the insulating bearing is generally used at one end (usually arranged at the extension end of non main shaft). For the occasions with high requirements, the insulating bearing is installed at both ends. The insulating bearing used is generally the method of adding (coating) insulating layer to the outer ring, and the inner and outer rings are also used in some occasions.

CoatMaster as the trademark of China Bearing manufacturer focus on manufacture complete Electrially insulated bearing such as

— Electrially Insulated Deep Groove Ball Bearing
— Electrially Insulated Cylindrical roller bearing
— Electrially Insulated self-aligning ball bearing
— Electrially Insulated angular contact ball bearing
— Electrially Insulated taper roller bearing
— Electrially Insulated spherical roller bearing
— Electrially Insulated thrust roller bearing
— Hybrid ceramic ball bearing

CoatMaster is more than 10 years experience China Bearing manufacturer for Electrically Insulated bearing design and research,  depending on the rich exprience for special spraying process and advance equipment,  The quality of CoatMaster always to learn The top level Bearing manufacturer of the world, and the service life can meet 70% of The top brand level, but the price have very big competitive than them, more and more customers use our electrically insulated bearing to their application. we will keep our goat that to meet customer demand, keep going on improve our quality,service and our competitive power on the market.

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