Why insulated bearing used in motor?

Before answer why insulated bearing used in motor, we need to know what is Electrically insulated bearing? electric insulated bearing adopt the Special spraying process. The outer surface of the bearing is sprayed with high-quality coating, which has strong binding force with the substrate and good insulation performance. It can avoid the electric erosion of the induction current to the bearing, prevent the damage of the current to the grease, the rolling element and the raceway, and electrically insulated bearing improve the service life of the bearing. The process has been improved continuously. In the insulating bearing, there is a layer of 100 μ m thick coating on the outer or inner ring surface, which can withstand the voltage of up to 1000 V DC A special spraying process can form a coating with uniform thickness and strong adhesion, which can be further treated to avoid the influence of moisture and humidity.

Characteristics of electrically insulated bearings

  1. Resistant to electrical corrosion

By integrating insulation performance into the bearing, electrically insulated bearings can improve reliability and increase machine uptime by actually eliminating the problem of electrical corrosion

  1. High resistance

Alumina coating has a minimum resistance of 200MΩ and can withstand voltages up to 3000 V DC

  1. Stable electrical performance

Plasma spraying is usually hygroscopic and therefore easily susceptible to condensation and infiltration. To prevent this effect, Electrically insulated bearings are treated with a unique sealant.


It is mainly a frequency-converter motor powered by a frequency converter, especially a frequency-variable motor with a higher voltage and a frequency converter with a higher switching frequency. This needs to be determined according to the power state of the motor.

Normal grid power supply has no high-frequency voltage and current components. Generally, insulated bearings are not used. Only high-voltage motors such as 400 and above are used. It is not even necessary, but now the frequency conversion power supply, because the power quality contains a lot of high-frequency components, causing the motor shaft current to increase.

Therefore, this problem should be considered in the specifications above 400, and even smaller specifications also consider the installation of insulated bearings according to the use situation. For example, the main motors used in electric cars, electric rail cars, etc. are generally about 100KW, and they must be Electrically insulated Bearings (or use other insulation structures to ensure shaft current does not flow).

Electrically insulated bearing are widely used in many kinds of industry, Motors, generators and related equipment are in danger when current passes through the bearings. This not only damages the contact surfaces of the rolling elements and raceways in the bearing (electrical corrosion), but also quickly degrades the grease. Another additional risk comes from high-frequency currents in motors and generators, which can form a loop through the parasitic capacitance inherent in the device. Increased risk of damage if frequency converter is used.

CoatMaster as the China bearing manufacturer & exporter & supplier, it can supply complete electrically insulated bearing, Our large quantity insulated deep groove ball bearing Stock can meet your need with good quality and fast delivery, Also you can find FAG Current insulated Bearing, the other type and brand insulated deep groove ball bearing, insocoat tapered roller bearing, Current-Insulated Bearings. CoatMaster would like to serve all of the industry customers bearing soluations, please contact with CoatMaster Technical Team.

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