Electrically insulated bearings use a special spraying process to spray a high-quality coating on the outer surface of the bearing. The coating has a strong bond with the substrate and good insulation performance, which can avoid the electro-corrosion of the bearing by the induced current, prevent the current from damaging the grease, rolling elements and raceways, and increase the service life of the bearing. The process is constantly being improved. In the insulating bearing, there is a 100μm thick coating on the outer or inner ring surface, which can withstand a voltage of up to 1000 V DC. The special spraying process can form a coating with uniform thickness and extremely strong adhesion, and after further treatment, it can be unaffected by moisture and humidity.
Advantages of electrical insulating bearings
Insulated bearings play an increasingly important role in modern industry due to their excellent insulation performance, wear resistance and stability. They are widely used in the fields of electricity, machinery manufacturing, chemical industry, etc., providing stable and reliable support for production equipment in various industries. By choosing Shandong insulating bearings, enterprises can reduce equipment failure rate, improve production efficiency, and thus achieve better economic benefits.
Application of electrically insulated bearings in motors
1. Causes and hazards of motor shaft voltage and bearing current
During motor operation, any imbalance in the stator and rotor magnetic circuits or in the phase current around the shaft can generate a rotating system flux. When the shaft rotates, these fluxes can generate a potential difference at both ends of the shaft, which is called shaft voltage. The shaft voltage can excite a circulating current in the loop (closed circuit) formed by the shaft and the housing through the bearings at both ends, which is called shaft current.
In addition, the rotor core has a lot of residual magnetism. For wound rotor motors, if two or more points of the winding are short-circuited to the rotor core or the 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 drive voltage, the pulse rise time, the cable length and other factors. The greater the power of the motor, the higher the drive voltage, the steeper the rising edge of the drive voltage, and the shorter the cable, the greater the bearing current.
2. Measures to block shaft current - use insulated bearings
In order to avoid shaft current damage to the bearing, effective measures should be taken to isolate the shaft current.
For large motors with independent bearing seats at both ends, an insulating gasket made of insulating material can be placed between the bearing seat and the metal base. For motors with ordinary bearings and housings assembled as one, an insulating bearing is generally used at one end (usually arranged at the non-spindle extension end). For occasions with higher requirements, insulating bearings are installed at both ends. The insulating bearings used are generally the method of adding (usually coating) an insulating layer to the outer ring. In some occasions, both the inner and outer rings are also added with insulating layers.
