6326/C3VL2071 130*280*58mm Insulated Insocoat bearings for Electric
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Electric motors, generators and associated equipment are at risk
when an electric current passes through their bearings. This can
damage the contact surfaces of rolling elements and raceways in the
bearings (electrical erosion) and rapidly degrade the grease. An
additional risk in electric motors and generators comes from high
frequency currents caused by the inherent stray capacitance.
The risk of damage increases where the application uses a frequency
Insulated Insocoat bearings are designed to prevent electric
current from passing through the bearing
have the external surfaces of either their inner or outer ring
coated with an insulating aluminium oxide layer, by applying a
sophisticated plasma-spray process for an outstanding quality
are a very cost-effective solution compared with other insulation
Electrical pitting often occurs in the use of rolling bearings in
high power electromotor, wind turbine generator and rail vehicles
motor systems and cause sparks that damage the rolling contact
surface, ultimately lead to bearing failure.
Electric insulated bearings therefore have been created and take
the place of non-insulated bearings. we applies advanced surface
modification process overlay a ceramic coating on the bearing ring,
to insulate the electrical current flow into bearing substrate, so
the electrical pitting is prevented and bearing's service life is
It is significantly more cost-effective to provide for the use of
electrically insulated bearings at the planning stage. As a result,
customer benefit is increased through reduced maintenance costs and
higher machine availability.
SAT series are the electrically insolated bearing products
developed and marketed by us The insulation has a guaranteed
breakdown resistance of at least 1000V AC or DC. We can also
develop tailored modes for customer on types and precision levels,
as well as higher electrical insulation.
Protection against electrical erosion
With insulating properties integrated into the bearing, INSOCOAT
bearings can improve reliability and increase machine uptime by
virtually eliminating the problem of electrical erosion.
High electrical resistance
The aluminium oxide coating provides a minimum electrical
resistance of 200 MΩ and can withstand voltages up to 3 000 V DC.
Consistent electrical performance
Plasma-spray coatings are normally hygroscopic and, therefore,
vulnerable to penetration caused by condensation. To protect
against this effect, INSOCOAT bearings are treated with a unique
Application of Insulated Bearings in Electric motors
1. Causes and harm of motor shaft voltage and bearing current
In the operation of the motor, any imbalance in the phase currents
in or around the rotor’s magnetic circuit can produce a rotating
system flux linkage.
When the shaft rotates, these flux chains can generate a potential
difference across the shaft. This potential difference is called
the shaft voltage. The shaft voltage can excite a circulating
current through a loop formed by the two ends of the bearing in the
shaft and the casing (closed circuit), which is called the shaft
In addition, the rotor core has more remanence, For a wound rotor
motor, shaft voltage and shaft current are generated if two or more
windings are short-circuited to the rotor core or the shaft. the
bearing current is related to the structure of the motor, the power
of the motor, the magnitude of the drive voltage, the rise time of
the pulse, the length of the cable, etc. The larger 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 larger
the bearing current.
2. How to block shaft current – use electrically insulated bearings
In order to avoid damage to the bearing caused by the shaft
current, effective measures should be taken to isolate the shaft
current. For large motors with independent bearing housings at both
ends, spacers made of insulating material can be placed between the
bearing housing and the metal base. For a motor in which an
ordinary bearing and a casing are integrated, an Electrically
insulated bearing is generally used at one end thereof (often
arranged at the non-spindle end).
For high requirements, insulated bearings are installed at both
ends. The insulating bearing used is generally a method of
attaching (generally coating) an insulating layer to the outer
ring. In some cases, the inner and outer rings are also provided
with an insulating layer.
Electrically insulated bearings avoid damage caused by electrical
corrosion, so they are more reliable in operation than in
conventional bearings. And compared to other insulation methods,
such as shaft or housing insulation, etc. More cost effective and
reliable. Insulated bearings have the same dimensions and basic
technical features as non-insulated bearings Suitable for motors,
generators, especially variable frequency motors.
CoatMaster (China Bearing manufacturer), As the exprienced
Electrically Insulated Bearing manufacturer of China, Not only
produce insulated deep groove ball bearing, insulated cylindrical
roller bearing, insulated tapered roller bearing, insulated angular
contact ball bearing and the other type of insulated bearing, but
also supply complete and expert solution for electric motor and the
other applications where need insulated bearing. if you have
problem make you distracted about the insulated bearing, just
contact with our bearing technical team.