SKF INSOCOAT bearings with electrically insulating coating

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SKF INSOCOAT bearings with electrically insulating coating are the special design special used in Electric motor. This design have the same dimension with the normally bearings, same weight and same cage, but INSOCOAT bearing have the electrially insulating coating on the outer ring or inner ring. At the present, Some bearing manufacturer can supply this kind of electrially insulating bearings, SKF, FAG, NSK, NTN, NKE, CoatMaster, ZKL, GRW Bearing.

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 converter.

INSOCOAT bearings are designed to prevent electric current from passing through the bearing. The external surfaces of either their inner or outer ring are coated with an insulating aluminium oxide layer, by applying a sophisticated plasma-spray process for an outstanding quality finish. The solutions are very cost-effective compared with other insulation methods.

They must be robust enough to operate in electrical equipment with modern AC technology. The passage of electric current through rolling bearings can lead to damage in a relatively short period of time. Small craters caused by electric current passage which have been tolerated occasionally in the past are no longer acceptable. SKF, as a consequence, has developed the INSOCOAT bearing range. These bearings have special coated outer rings with an electrically-insulated layer for a breakdown voltage up to 1,000 V.

To ensure smooth, trouble-free operation, it is necessary to prevent the bearing from electric current passage. The contact areas between housing, outer ring, rolling elements, inner ring and shaft can act as electric contacts. The resulting arcs – characterised by very high temperatures similar to that produced by melting and welding processes – will damage rolling elements as well as raceways of bearing rings. Typical damage is characterised by craters and false brinelling.

Electrially Insulating Bearing have many kinds of design

— Insulated deep groove ball bearing
— Insulated cylindrical roller bearing
— Insulated tapered roller bearing
— Insulated spherical roller bearing
— Insulated angular contact ball bearing
— Insulated thrust roller bearing
— Insulated linear ball bearing

Bearing design

The insulating coating on the outer ring of the INSOCOAT bearing is made from aluminium oxide and applied using plasma spraying technology. SKF has carried out extensive research and development in this area and is pursuing further improvement of the process. The latest phase of the development is the ability to handle a 1,000V dielectric breakdown voltage.

Design characteristics of the bearing include:

  • ISO standard dimensions and tolerances
  • Interchangeability with non-insulated bearing types
  • Suitability for all common housing types
  • Dielectric breakdown voltage optional up to 500V or 1,000V.
  • Coating thickness of about 0.05 mm
  • Durability of coating
  • High thermal stability

Insulated Deep Groove Ball Bearing

Designation Principal dimensions Basic load ratings Fatique load limit Speed ratings
dynamic static Reference speed Limiting speed
d[mm] D[mm] B[mm] C[kN] C0[kN] Pu[kN] [r/min] [r/min]
6314/C3VL0241 70 150 35 111 68 2.75 9500 6300
6314 M/C3VL0241 70 150 35 111 68 2.75 9500 9000
6215/C3VL0241 75 130 25 68.9 49 2.04 10000 6700
6315/C3VL0241 75 160 37 119 76.5 3 9000 5600
6315 M/C3VL0241 75 160 37 119 76.5 3 9000 8000
6216/C3VL0241 80 140 26 72.8 55 2.2 9500 6000
6316/C3VL0241 80 170 39 130 86.5 3.25 8500 5300
6316 M/C3VL0241 80 170 39 130 86.5 3.25 8500 7500
6217/C3VL0241 85 150 28 87.1 64 2.5 9000 5600
6317/C3VL0241 85 180 41 140 96.5 3.55 8000 5000
6317 M/C3VL0241 85 180 41 140 96.5 3.55 8000 7500
6218/C3VL0241 90 160 30 101 73.5 2.8 8500 5300
6318/C3VL0241 90 190 43 151 108 3.8 7500 4800
6318 M/C3VL0241 90 190 43 151 108 3.8 7500 7000
6219/C3VL0241 95 170 32 114 81.5 3 8000 5000
6219 M/C3VL0241 95 170 32 114 81.5 3 8000 7500
6319/C3VL0241 95 200 45 159 118 4.15 7000 4500
6319 M/C3VL0241 95 200 45 159 118 4.15 7000 6300
6220/C3VL0241 100 180 34 127 93 3.35 7500 4800
6320/C3VL0241 100 215 47 182 140 4.75 6700 4300
6320 M/C3VL0241 100 215 47 182 140 4.75 6700 6000
6222/C3VL0241 110 200 38 151 118 4 6700 4300
6222 M/C3VL0241 110 200 38 151 118 4 6700 6300
6322/C3VL0241 110 240 50 216 180 5.7 6000 3800
6322 M/C3VL0241 110 240 50 216 180 5.7 6000 5300
6224/C3VL0241 120 215 40 153 118 3.9 6300 4000
6324/C3VL2071 120 260 55 216 186 5.7 5600 3400
6324 M/C3VL2071 120 260 55 216 186 5.7 5600 5000
6226/C3VL2071 130 230 40 163 132 4.15 5600 3600
6326/C3VL2071 130 280 58 242 216 6.3 5000 3200
6326 M/C3VL2071 130 280 58 242 216 6.3 5000 4500
6228/C3VL2071 140 250 42 174 150 4.55 5300 3400
6328/C3VL2071 140 300 62 265 245 7.1 4800 3000
6328 M/C3VL2071 140 300 62 265 245 7.1 4800 4300
6230/C3VL2071 150 270 45 186 166 4.9 5000 3200
6330/C3VL2071 150 320 65 286 285 7.8 4300 2800
6332 M/C3VL2071 160 340 68 291 285 7.65 4000 3800
6334 M/C3VL2071 170 360 72 332 340 8.8 3800 3400
6336 M/C3VL2071 180 380 75 371 405 10.4 3600 3200

 

Insulated Cylindrical Roller Bearing

Designation Principal dimensions Basic load ratings Fatique load limit Speed ratings
dynamic static Reference speed Limiting speed
d[mm] D[mm] B[mm] C[kN] C0[kN] Pu[kN] [r/min] [r/min]
NU 1010 ECP/C3VL0241 50 80 16 46.8 56 6.7 9500 9500
NU 210 ECM/C3VL0241 50 90 20 73.5 69.5 8.8 8500 9000
NU 310 ECM/C3VL0241 50 110 27 127 112 15 6700 8000
NU 1011 ECP/C3VL0241 55 90 18 57.2 69.5 8.3 8500 8500
NU 1011 ECML/C3VL0241 55 90 18 57.2 69.5 8.3 8500 13000
NU 211 ECM/C3VL0241 55 100 21 96.5 95 12.2 7500 8000
NU 311 ECM/C3VL0241 55 120 29 156 143 18.6 6000 7000
NU 1012 ML/C3VL0241 60 95 18 37.4 44 5.3 8000 13000
NU 1012 ECP/C3VL0241 60 95 18 58.3 73.5 8.8 8000 8000
NU 212 ECM/C3VL0241 60 110 22 108 102 13.4 6700 7500
NU 312 ECM/C3VL0241 60 130 31 173 160 21.2 5600 6700
NU 1013 ECP/C3VL0241 65 100 18 62.7 81.5 9.8 7500 7500
NU 213 ECM/C3VL0241 65 120 23 122 118 15.6 6300 6700
NU 313 ECM/C3VL0241 65 140 33 212 196 25.5 5300 6000
NU 1014 ECM/C3VL0241 70 110 20 76.5 93 12 7000 7000
NU 1014 ECP/C3VL0241 70 110 20 76.5 93 12 7000 7000
NU 214 ECM/C3VL0241 70 125 24 137 137 18 6000 6300
NU 314 ECM/C3VL0241 70 150 35 236 228 29 4800 5600
NU 1015 M/C3VL0241 75 115 20 58.3 71 8.5 6700 6700
NU 215 ECM/C3VL0241 75 130 25 150 156 20.4 5600 6000
NU 315 ECM/C3VL0241 75 160 37 280 265 33.5 4500 5300
NU 315 ECP/VL0241 75 160 37 280 265 33.5 4500 5300
NU 1016 ECM/C3VL0241 80 125 22 99 127 16.3 6000 6000
NU 216 ECM/C3VL0241 80 140 26 160 166 21.2 5300 5600
NU 316 ECM/C3VL0241 80 170 39 300 290 36 4300 5000
NU 1017 M/C3VL0241 85 130 22 68.2 86.5 10.8 6000 6000
NU 217 ECM/C3VL0241 85 150 28 190 200 25 4800 5300
NU 317 ECM/C3VL0241 85 180 41 340 335 41.5 4000 4800
NU 1018 M/C3VL0241 90 140 24 80.9 104 12.7 5600 5600
NU 218 ECM/C3VL0241 90 160 30 208 220 27 4500 5000
Designation Principal dimensions Basic load ratings Fatique load limit Speed ratings
dynamic static Reference speed Limiting speed
d[mm] D[mm] B[mm] C[kN] C0[kN] Pu[kN] [r/min] [r/min]
NU 318 ECM/C3VL0241 90 190 43 365 360 43 3800 4500
NU 1019 ML/C3VL0241 95 145 24 84.2 110 13.2 5300 5300
NU 219 ECM/C3VL0241 95 170 32 255 265 32.5 4300 4800
NU 319 ECM/C3VL0241 95 200 45 390 390 46.5 3600 4300
NU 1020 M/C3VL0241 100 150 24 85.8 114 13.7 5000 5000
NU 220 ECM/C3VL0241 100 180 34 285 305 36.5 4000 4500
NU 320 ECM/C3VL0241 100 215 47 450 440 51 3200 3800
NU 1022 M/C3VL0241 110 170 28 128 166 19.3 4500 4500
NU 222 ECM/C3VL0241 110 200 38 335 365 42.5 3600 4000
NU 322 ECM/C3VL0241 110 240 50 530 540 61 3000 3400
NU 1024 M/C3VL2071 120 180 28 134 183 20.8 4000 4000
NU 224 ECM/C3VL0241 120 215 40 390 430 49 3400 3600
NU 324 ECM/C3VL0241 120 260 55 610 620 69.5 2800 3200
NU 1026 M/C3VL2071 130 200 33 165 224 25 3800 3800
NU 226 ECM/C3VL2071 130 230 40 415 455 51 3200 3400
NU 326 ECM/C3VL2071 130 280 58 720 750 81.5 2400 3000
NU 1028 M/C3VL2071 140 210 33 172 245 27 3600 3600
NU 228 ECM/C3VL2071 140 250 42 450 510 57 2800 3200
NU 328 ECM/C3VL2071 140 300 62 780 830 88 2400 2800
NU 1030 M/C3VL2071 150 225 35 194 275 30 3200 3200
NU 230 ECM/C3VL2071 150 270 45 510 600 64 2600 2800
NU 330 ECM/C3VL2071 150 320 65 900 965 100 2200 2600

 

Common suffixes used for INSOCOAT bearings are:
VL024 and VA309 breakdown voltage to 500V and VL0241 and VA3091 breakdown voltage up to 1,000V. VA309 and VA3091 are applied to bearings for traction motor applications.

In principle, electrically-insulated bearings can be of any type. Most common bearing types include cylindrical roller bearings and deep groove ball bearings with outside diameters larger than 75 mm for traction motor designs, stationary electric motors (medium and large types), generators and special applications including submersible pumps. Also electrically-insulated taper roller bearings could be used as wheel bearings for tram and suspension tube bearings for electric railway vehicles.