Electrical Protection: Breakdown voltage up to 3000V. Blocks stray currents to prevent electrical corrosion.
Standard Dimensions: Built to international standards for direct replacement of same-model bearings.
Flexible MOQ: Low Minimum Order Quantity (MOQ). Supports both small-batch and large-volume orders.
Service Response: All inquiries are answered within 24 hours.
TFL 6228/C3VL2071 is a 100% equivalent and direct replacement for large-size insulated bearings from SKF and FAG in terms of mechanical dimensions (140x250x42mm), standard pressed steel cage structure, C3 clearance, and VL2071 inner-ring standards. All bearings undergo strict voltage resistance and insulation resistance testing before dispatch. Customers can achieve direct replacement without changing the original motor shaft or end-shields.
| SKF | FAG |
|---|---|
| 6228/C3VL2071 | 6228-J20C-C3 |
Supplying technically challenging inner-ring insulated bearings with a 140mm bore (controlling bore-coating adhesion and tolerances is far more complex than on the outer ring) is a test of premium supply chains and quality management. Relying on a robust high-end power transmission network and an ISO 9001 certified quality control system, TFL seamlessly integrates imported temperature-controlled plasma spraying processes with precision large-bearing standards. We provide high-reliability products that rival top global brands, backed by a professional engineering team for technical diagnostic support. With rapid-response stock availability and No MOQ, TFL is dedicated to helping global clients eliminate lead-time risks on large specialized parts, achieving significant cost optimization.
Inner-Ring Insulation (VL2071) — High-bond alumina coating on the bore and side faces to isolate high-voltage stray currents directly at the source.
Large-Bore Medium Series — Dimensions 140 x 250 x 42 mm, built to support heavy radial loads safely (weight approx. 7.64 kg).
Optimal Insulation Resistance — Maintains 50–200 MΩ, efficiently eliminating VFD-induced raceway fluting.
TFL 6228/C3VL2071 inner-ring insulated bearings are developed for VFD equipment where “the outer ring is strictly prohibited from being insulated,” while facing significant temperature rises and VFD leakage currents. Typical applications encompass rail transit and large AC traction motors requiring absolute stator grounding, metallurgical exhaust fans with tight cooling jackets, and high-precision split-housing centrifugal compressors. Its standard steel cage ensures smooth medium-to-high speed runs, providing a long-lasting electrical isolation barrier without altering housing dimensions.
In AC traction motors for high-power locomotives by CRRC or Alstom, to ensure strict electromagnetic compatibility (EMC) and direct housing grounding designs, the bearing’s outer ring is strictly prohibited from being insulated. TFL 6228/C3VL2071 utilizes its VL2071 plasma-sprayed ceramic layer in the bore to cut off the leakage circuit directly at the rotor shaft. It blocks high-frequency shaft currents while its lightweight steel cage ensures smooth rotation, making it a highly recommended alternative for traction motor overhauls.
In large centrifugal exhaust fans (e.g., Howden systems) operating under continuous high-temperature metallurgy conditions, massive amounts of exhaust heat conduct along the rotor shaft, causing extreme inner-ring temperature rises. Because the housing features an ultra-tight water-cooling jacket, applying a coating to the outer ring is impractical and severely impedes heat dissipation. TFL 6228/C3VL2071’s inner-ring insulation design perfectly matches this demand, blocking high-frequency current hazards without interfering with cooling heat transfer, while its C3 clearance safely absorbs severe thermal expansion caused by the internal-hot and external-cold temperature gradient.
For large multi-stage VFD centrifugal compressors by Atlas Copco or MAN Energy Solutions used in chemical plants, the housing often adopts a “top-bottom split” design to facilitate lifting the large-shaft rotors. This structure demands absolute outer-ring conformance to the bore to ensure micron-level concentricity. TFL 6228/C3VL2071 resolves this contradiction with its inner-ring insulation. Without altering the original precision housing assembly processes, it isolates high-frequency VFD currents right at the rotor shaft, while its standard pressed steel cage ensures minimal running resistance under high-speed operations.
*The brands and series mentioned are provided for industry illustration only. Final bearing selection should be confirmed through verification of dimensions, clearance class, insulation type, and operating conditions. For selection assistance or technical consultation, please contact the TFL engineering team for support.
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