High Precision Insulated Bearing 6326-M-J20AA-C3 is Deep Groove Ball Bearing design. its dimension is 130×280×58mm, it has the same dimension and the same design with normal chrome steel 6326-M bearing. but the most different is 6326-M-J20AA-C3 bearing with Aluminium Oxide Coating. the coating can Electrical Resistance Voltages up to 3000 V DC. This kind of bearing are widely used in high quality demand application like traction motor.
Electrically Insulated Bearing can protect the machine to be exposed to electrical current. In a worst-case scenario, this can damage raceways and rolling elements, which in turn, causes the motor or generator to fail prematurely and without warning. On top of the extra expenses incurred for repairs, this also means additional costs caused by machine downtime and the resulting production losses.
Current-Insulated Bearings as a Preventive Measure · Typical Damage Caused by Electrical Current Passing through the Bearing, the ohmic resistance of the bearing. With higher frequency AC voltage (often encountered in converters!), it depends on the capacitive reactance of the bearing. Basically, a current-insulated bearing acts like a resistor and capacitor connected in parallel. To ensure good insulation, the ohmic resistance should be as high as possible, and the capacitance should be as low as possible.
| Designation | Mass | Dimensions | R |
|
|
| Load Rating | Fatigue
Limit Load | Limiting
Speed | Reference
Speed |
| EASIER | (kg) | d | D | B | Min | D1 | D2 | d | dyn.Cr | stat.Cor | Cur |
|
|
| 6212-M-J20B-C4 | 0,98 | 60 | 110 | 22 | 1,5 | 95,6 |
| 76,1 | 52 | 36 | 2,24 | 14 000 | 6 800 |
| 6213-J20B-C4 | 1 | 65 | 120 | 23 | 1,5 | 103,1 |
| 82,3 | 60 | 41,5 | 2,55 | 13 000 | 6 300 |
| 6313-M-J20AA-C5 | 2,55 | 65 | 140 | 33 | 2,1 | 117,5 |
| 88,6 | 93 | 60 | 3,95 | 11 000 | 6 400 |
| 6214-2RSR-J20AA-C3 | 1,11 | 70 | 125 | 24 | 1,5 |
| 110,7 | 86,8 | 62 | 44 | 2,9 | 12 000 | 6 100 |
| 6215-M-J2B-C4 | 1,42 | 75 | 130 | 25 | 1,5 | 112,8 |
| 92,5 | 65,5 | 49 | 3,35 | 11 000 | 5 900 |
| 6215-M-P6-J20AA-R85-105 | 1,42 | 75 | 130 | 25 | 1,5 | 112,8 |
| 92,5 | 65,5 | 49 | 3,35 | 11 000 | 5 900 |
| 6315-M-J20AA-C3 | 3,74 | 75 | 160 | 37 | 2,1 | 133,2 |
| 101,8 | 114 | 76,5 | 4,65 | 9 500 | 5 800 |
| 6016-M-J20AA | 0,997 | 80 | 125 | 22 | 1,1 | 111 |
| 94 | 47,5 | 40 | 2,34 | 12 000 | 6 500 |
| 6216-J20AA-C3 | 1,46 | 80 | 140 | 26 | 2 | 121,3 |
| 98,8 | 72 | 54 | 3,45 | 11 000 | 5 500 |
| 6316-J20AA-C3 | 3,75 | 80 | 170 | 39 | 2,1 | 141,8 |
| 108,6 | 122 | 86,5 | 5,2 | 9 000 | 5 500 |
| 6316-M-J20B-C4 | 4,44 | 80 | 170 | 39 | 2,1 | 141,8 |
| 108,6 | 122 | 86,5 | 5,2 | 9 000 | 5 500 |
| F-808916.6316-J20AA | 3,69 | 80 | 170 | 39 | 2,1 | 141,8 |
| 108,6 | 122 | 86,5 | 5,2 | 9 000 | 5 500 |
| 6317-M-J20AA-C3 | 5,05 | 85 | 180 | 41 | 3 | 151,6 |
| 114,4 | 132 | 96,5 | 5,8 | 8 000 | 5 300 |
| 6218-J20AA-C3 | 2,21 | 90 | 160 | 30 | 2 | 139,4 |
| 112,3 | 96,5 | 72 | 4,2 | 9 000 | 5 100 |
| 6318-M-J20AA-C3 | 6,14 | 90 | 190 | 43 | 3 | 157,1 |
| 123,8 | 134 | 102 | 5,8 | 8 000 | 5 100 |
| 6319-M-J20AA-C4 | 7,05 | 95 | 200 | 45 | 3 | 166,9 |
| 129,1 | 146 | 114 | 6,4 | 7 500 | 4 950 |
| 6220-J20C-C3 | 3,3 | 100 | 180 | 34 | 2,1 | 154,8 |
| 124,7 | 122 | 93 | 5,4 | 8 000 | 4 800 |
| 6220-M-J20AA-R95-120 | 3,9 | 100 | 180 | 34 | 2,1 | 154,8 |
| 124,7 | 122 | 93 | 5,4 | 8 000 | 4 800 |
| 6320-M-J20AA-C3 | 8,64 | 100 | 215 | 47 | 3 | 179 |
| 138,6 | 163 | 134 | 7,4 | 7 000 | 4 650 |
| 16021-M-J20AA-C5 | 1,42 | 105 | 160 | 18 | 1 | 141,2 |
| 124,2 | 54 | 54 | 2,39 | 9 500 | 3 950 |
| 6322-M-J20AA-C3 | 11,7 | 110 | 240 | 50 | 3 | 197,4 |
| 153,4 | 190 | 166 | 8,6 | 6 300 | 4 150 |
| 6324-M-J20AA-C3 | 15 | 120 | 260 | 55 | 3 | 214,9 |
| 165,1 | 212 | 190 | 9 | 6 000 | 3 850 |
| 6326-M-J20AA-C3 | 18,3 | 130 | 280 | 58 | 4 | 231,2 |
| 178,9 | 228 | 216 | 9,8 | 5 600 | 3 500 |
| 6230-J20AA | 10,3 | 150 | 270 | 45 | 3 | 229,1 |
| 191,6 | 176 | 170 | 7,8 | 5 600 | 3 350 |
| 6336-M-J20AA-C4 | 43 | 180 | 380 | 75 | 4 | 317 |
| 245,2 | 355 | 405 | 16,3 | 3 800 | 2 440 |
Insulated bearings provided by EASIER combat electrical erosion in a wide range of conditions, including high humidity. Sealed protective coatings on the outer or inner rings integrate insulating properties into the bearing. They eliminate premature bearing failures caused by stray electric current in applications including:
• Industrial electric motors
• Traction motors
• Generators
The Coating Process
The plasma spraying process involves generating an arc between two electrodes to ionize a noble gas that is
issued from the plasma torch. The resulting plasma jet is used to carry the injected aluminum oxide powder. This powder is melted by the heat and sprayed at high speed
onto the outer or inner ring. When applied in this manner, the oxide layer adheres extremely well to the base
material. It is then sealed and ground to size.
Electric Resistance
The coatings are subjected to a 100% quality inspection and guarantee a dielectric strength of at least 1000 VDC (J20AA, J20C) or 500 VDC (J20B), respectively.
Below this voltage, the insulating layer permits only extremely low levels of current to flow through the bearing. It offers resistance to DC currents and to
AC currents:
DC resistance
At room temperature, the layer typically has a
DC resistance of 1–10 GOhm, depending on the bearing size. As the temperature increases, the DC resistance
decreases exponentially, typically by approx. 40–50 % per 10 K. But even at operating temperatures of 60 °C
or even 80 °C, the insulating layer still has a resistance of several MOhm. According to Ohm’s law (I = U/R),
this means that voltages of up to 1 000 V only produce currents that are significantly below 1 mA, which are not critical for bearings.
AC resistance
The insulated unit acts like a capacitor (C) which can accumulate charges. When exposed to an AC voltage, this causes an alternating current to flow through the
contact area between the rolling element and raceway.
In the case of a harmonic time dependence with
angular frequency w, the rms values for current and voltage are calculated using the formula
Principle bearing types for traction motor applications
• cylindrical roller bearings
• electrically insulated cylindrical roller bearings
• electrically insulated deep groove ball bearings
• hybrid cylindrical roller bearings with ceramic rollers
• hybrid deep groove ball bearings with ceramic balls
• traction motor bearing units based on cylindrical roller bearings and
deep groove ball bearings
• Sensorised traction motor bearing unit
• Regreasable traction motor bearing unit
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