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6328/C3VL2071 Electrically Insulated Ball Bearings

6328/C3VL2071 Electrically Insulated Ball Bearings

Reliable 6328/C3VL2071 - Built to Your Specs & Drawings

$ 514 /Each
  • Customized Logo: Min. Order 1 Piece
  • Customized Packaging: Min. Order 1 Piece
  • Inventory: In stock
  • Country of Origin: China
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Product Parameters

  • Model 6328/C3VL2071
  • Equivalent Interchange 6328/C3VL2071 (SKF); 6328-J20C-C3 (FAG); 6328-M-C3-SQ77E (NKE);
  • Product Category Electrically Insulated Ball Bearings
  • Coating Suffix VL2071
  • Insulating Coating Types Inner ring insulation coating
  • Manufacturers TFL
  • Bore Diameter 140.0 mm
  • Outside Diameter 300.0 mm
  • Width 62.0 mm
  • Net Weight 18.2kg
  • Basic Dynamic Load Rating 265.0 kN
  • Basic Static Load Rating 245.0 kN
  • Reference Speed 4800.0 r/min
  • Breakdown Voltage (DC) 1000 ~3000 V
  • Layer Thickness 100~500 µm
  • Electrical Resistance 50~200 MΩ
  • Cage Material Sheet metal
  • Radial Internal Clearance C3
  • ROHS Compliant
  • REACH Compliant

6310/C3VL0241 Equivalent Interchange Brands

TFL 6328/C3VL2071 is a 100% equivalent and direct replacement for large-size insulated bearings from SKF and FAG in terms of mechanical dimensions (140x300x62mm), 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 NKE
6328/C3VL2071 6328-J20C-C3 6328-M-C3-SQ77E

Why Choose TFL?

Supplying ultra-heavy-duty inner-ring insulated bearings with a 140mm bore and weighing over 20kg (where controlling bore-coating adhesion is far more complex than on the outer ring) is a test of premium supply chains and quality management. Relying on a robust premium power transmission supply chain network and a strict quality control system, TFL provides high-quality products that deeply integrate advanced coating processes with precision mechanical standards. We not only provide high-reliability anti-erosion solutions rivaling top global brands but also offer professional technical support from our engineering team for selection and diagnostics. 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.

electricllay insulated ball bearing 6328/C3VL2071 inner ring coating bearing

Features of 6328/C3VL2071

Common Applications of Electrically Insulated Bearings

TFL 6328/C3VL2071 is specifically developed for large-scale VFD drive systems with restricted housing assemblies that concurrently face heavy loads and VFD leakage currents. Typical applications encompass MW-class generators where the stator must be grounded for EMC shielding, metallurgy exhaust fans with tight cooling jackets, and high-precision split-housing centrifugal compressors. The standard pressed steel cage maintains excellent low-friction performance under continuous steady-state runs, while the inner-ring ceramic insulation provides a long-lasting, safe anti-erosion barrier without altering original precision mechanical fits.

Inner ring electrically insulated bearing, used for variable frequency motors

Large AC Motors & Generators

In MW-class large generators and main drive VFD motors manufactured by Siemens or ABB, to meet strict electromagnetic compatibility (EMC) and grounding specifications, the motor end-shield must maintain direct metallic contact with the bearing’s outer ring. Under this design, traditional outer-ring insulated bearings are completely inapplicable. TFL 6328/C3VL2071 utilizes an inner-bore insulation design, which safely and firmly supports the massive rotor weight via the heavy-duty 63 series structure while intercepting high-frequency leakage currents directly at the shaft journal interface. Its pressed steel cage delivers exceptionally low rotational friction, making it the ideal solution for large generator overhauls.

heavy duty centrifugal fans and inner ring coating insulated bearings

Heavy Water-Cooled Exhaust Fans in Metallurgy

In heavy centrifugal exhaust fans by Howden operating under continuous high-temperature metallurgical environments, extreme exhaust heat conducts along the rotor main shaft. The bearing's outer ring is usually mounted in a tight water-cooling jacket for maximum heat-dissipation transfer. Applying a ceramic coating on the outer ring here would block heat dissipation and make the coating highly vulnerable to damage during tight fits. TFL 6328/C3VL2071 bypasses housing assembly limits using its inner-ring VL2071 coating. Its standard steel cage adapts to steady high-speed operations, and the C3 clearance resolves differential thermal expansion caused by internal heat and external cooling, thoroughly curing inverter-induced electrical erosion and extending bearing life.

inner ring coating bearings for centrifugal compressor

Split-Housing High-Pressure Compressors

For large multi-stage centrifugal compressors by Atlas Copco or MAN Energy Solutions used in chemical air separation units, the housing often adopts a “top-bottom split” design to facilitate the lifting of large-shaft rotors. This structure imposes micron-level tolerances on the concentricity and surface parameters of the housing bore. TFL 6328/C3VL2071 resolves this mechanical assembly 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 and energy consumption 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.

Q&A

How does the VFD carrier frequency (e.g., increasing from 2 kHz to 8 kHz or 16 kHz) affect bearing electrical erosion? How does the TFL 6328/C3VL2071 address this change?

Higher carrier frequencies in VFDs result in quieter motor operation, but they also multiply the number of high-frequency switching transitions (dv/dt changes) per second. This dramatically increases the charging/discharging cycles of the bearing's oil-film capacitance, skyrocketing the energy of high-frequency induced leakage currents and accelerating standard bearing grease carbonization and fluting failures. The TFL 6328/C3VL2071 utilizes a dense, solid alumina physical medium with exceptionally low parasitic capacitance. It completely blocks these high-frequency leakage paths that multiply with carrier frequency, ensuring that the machine's electrical safety remains unaffected by VFD parameter adjustments.

Is there any non-destructive method to detect whether electrical erosion has already started inside the bearing or if early "fluting" wear has appeared, without dismantling the motor?

Yes, online non-destructive diagnosis can be performed using High-Frequency Envelope Acceleration analysis. When bearing raceways experience microscopic discharge melting under VFD shaft currents (early stage of erosion), balls passing over these microscopic pits generate periodic high-frequency shock vibrations. By utilizing the demodulated envelope spectrum of a vibration accelerometer, maintenance teams can sensitively capture characteristic spikes at outer or inner ring pass frequencies (BPFO/BPFI). This allows for early warning signs of feature shifts long before visible "fluting" washboard patterns develop on giant 6328-size bearing raceways, preventing catastrophic failures.

During actual operation, large heavy-duty shafting often exhibits minor alignment errors or shaft bending deflection. Will the resulting cyclic shear stresses cause the inner-ring ceramic coating of the TFL 6328/C3VL2071 to peel off?

No. During the operation of this massive 20.5kg 6328 bearing, minor shaft deflections generate cyclic alternating bending moments and shear stresses at the inner-bore mating surface. Conventional insulated bearings with insufficient bonding strength are highly prone to fatigue delamination under these alternating stresses. TFL utilizes an advanced temperature-controlled plasma spraying process to impact the molten high-purity ceramic onto the roughened bearing steel surface, forming an extremely high-strength micro-interlocking physical bond exceeding 40 MPa. Under long-term alternating loads, the coating easily maintains synchronized micro-elastic deformation with the steel substrate with zero risk of peeling or spalling.
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