Pre-tightening force for high-voltage tubular busbar crimping

The pre-tightening force for high-voltage tubular busbar crimping depends on the busbar material, cross-section, and connector type, typically requiring matched crimping tools capable of generating high, controlled forces to ensure reliable electrical and mechanical contact.

Recommended Crimping Practices

Tool and Die Matching: Use crimping tools and dies from the same manufacturer as the busbar connectors to ensure proper fit and force distribution. Mismatched tools can lead to under- or over-crimping, increasing contact resistance and risk of overheating or mechanical failure (Klauke expert knowledge) . Surface Preparation: Clean the conductor and remove any oxidation, especially for aluminum busbars, to ensure metallic contact. The stripped conductor length should be slightly longer than the connector insertion depth to accommodate crimp deformation (Klauke expert knowledge) . Crimping Sequence: For tubular connectors, crimping typically starts at the connection side and progresses toward the cable side. For splices, the first crimp is applied at the center. This ensures uniform compression and minimizes voids (Klauke expert knowledge) .

Force Considerations

High-Force Crimping Machines: Bench-top crimping machines for high-voltage applications, such as the TE HF-20 and HV-20, can generate up to 178 kN (20 tons) of crimp force for conductors up to 120 mm². This force range is sufficient for most high-voltage tubular busbar connections, ensuring low contact resistance and mechanical stability (TE Connectivity) . Progressive Forming: Some busbar joining methods use progressive forming, lancing, bending, and forging to achieve high contact pressures along the overlapping area. Pre-tightening forces in these processes are controlled to avoid deformation while maximizing electrical contact (Fenix Technical Paper) . Standards Compliance: Follow relevant standards such as ENA TS 41-11 for aluminum busbars and ENA TS 41-16 for copper systems. These standards specify the number of clamps and mechanical requirements but do not prescribe a single numeric pre-tightening force, emphasizing the use of manufacturer-recommended tools and dies (Northern Powergrid Specification) .

Practical Guidance

• Always use calibrated, high-force crimping tools appropriate for the busbar cross-section.
• Ensure uniform compression along the connector to prevent localized stress or electrical hotspots.
• Verify crimp quality through visual inspection and, if possible, pull tests to confirm mechanical integrity.
• Avoid excessive force that could deform the busbar or connector, as this can compromise both electrical and mechanical performance. Key Takeaway: While the exact pre-tightening force varies with busbar size, material, and connector type, high-voltage tubular busbar crimping typically requires high-force, precision-controlled crimping tools capable of generating forces in the range of tens to hundreds of kilonewtons, applied according to manufacturer and standard guidelines to ensure reliable, durable connections.