The current-carrying capacity of solid copper, with the flexibility rigid bars can't offer
Wherever high currents meet thermal expansion, vibration or installation tolerances, rigid copper bars reach their limits. They transfer mechanical forces to insulators, terminals and enclosures, loosen bolted joints and cause failures over their service life.
Flexible busbars, also known as laminated shunts or expansion joints, solve this problem. Their laminated construction of thin copper foils (0.1–0.5 mm) combines the conductivity of solid copper with the mechanical compliance that critical connection points need. The terminal ends are fused into solid contact pads by diffusion or press welding: no solder, no flux, no filler material. The result is a homogeneous copper joint with a negligible millivolt drop across the transition.
SVS manufactures every busbar to customer drawing or sample, from one-offs to series production.
Product overview
Flexible Busbars for Switchgear
See productExpansion compensation and vibration damping between main busbars, circuit breakers, transformers and busbar trunking systems. Rated currents up to 10,000 A. Where rigid connections are exposed to thermal movement for years, flexible busbars keep contact resistance stable and protect sensitive components such as bushings and ceramic insulators.
Flexible Busbars for EV Battery Packs
See productConnections between battery modules, packs, traction inverters and DC fast-charging circuits. A compact flat profile with high current density at low weight, designed for 400 V and 800 V architectures. The laminated construction withstands the vibration and thermal cycling that cause rigid connectors to fail in automotive applications.
Flexible Busbars for Energy Storage
See productIn BESS cabinets and PCS enclosures, high continuous currents flow in confined spaces, at ambient temperatures that can range from −20 °C to +50 °C in outdoor containers. Rigid copper bars cannot compensate for the resulting stack tolerances and module movement. Flexible busbars connect battery racks, DC busbars and inverters with stable contact resistance over thousands of charge and discharge cycles.
Flexible Busbars for Solar Inverters
See productCentral and string inverters place high demands on DC- and AC-side connections. Flexible busbars connect capacitor banks, IGBT/SiC modules, DC links and output terminals and are rated for 1500 V DC. Compared with cables, the flat design has lower inductance, an advantage in fast-switching power electronics.
Flexible Busbars for UPS and Data Centres
See productUninterruptible power supplies and data centre infrastructure require connections that stay cool and reliable under continuous load. Flexible busbars connect rectifiers, inverters, battery strings and distribution busbars with low contact resistance. Every watt lost at a joint becomes heat that the cooling system has to remove, and it worsens the PUE.
Looking for expansion bands made to your drawing? Just upload it and get a quote.
FAQ
A flexible busbar is an electrical conductor made of several thin copper foils (typically 0.1 to 0.5 mm), stacked and fused into solid contact pads at the terminal ends. This construction delivers the current-carrying capacity of solid copper, while the laminated body can bend and twist. Unlike a rigid busbar, a flexible busbar absorbs thermal expansion, vibration and installation tolerances without transferring mechanical forces to adjacent components.
Thin copper foils are stacked to the required cross-section. At the terminal ends, the foils are welded into a solid copper block under pressure and temperature, without solder or filler material. The contact surfaces are then drilled or machined to drawing and, if required, plated or insulated.
The current-carrying capacity depends on the cross-section, the permissible temperature rise and the installation conditions. Tell us the current, the available space and the ambient temperature, and we will advise you on the right design.
Yes. The flexible section can be insulated, for example with heat-shrink sleeving or silicone. The permissible operating temperature depends on the insulation material chosen.
Laminated busbars consist of stacked copper foils with solid welded terminal ends. They are compact and flat and mainly compensate for movement in one plane, such as thermal expansion and vibration. Braided straps made of copper strands, also called braided or earthing straps, can move in several directions but need more space for the same cross-section. We are happy to help you decide which design suits your application.
Yes. We supply flexible busbars to your drawing as one-offs, small batches or in series.
Yes, the terms are largely used interchangeably. "Expansion joint" is common in switchgear and transformer construction, while "shunt strap" or "laminated shunt" is used mainly in welding technology. For resistance welding machines, we offer dedicated shunt straps.
Connections You Can Rely On
We process highly conductive copper materials with a defined and verified purity level. All current-carrying surfaces are precisely machined and optimised for minimal contact resistance.
As a specialist in copper materials, we maintain one of the largest warehouses in Europe. Material availability and lean structures ensure short delivery times for custom busbars.
Contact surfaces, hole patterns and dimensions are manufactured exactly to your drawing, ensuring a precise fit across all production runs.
Our products are subject to strict quality inspections. For special requirements, individual tests are carried out according to defined specifications.
Every flexible busbar is manufactured to your drawing or sample, as a one-off, small batch or series production. Special designs are also available on request.
For decades, we have contributed our expertise to SVS products and, as an active member of the German Welding Society (DVS), have helped shape technical standards.
SVS Capabilities
Need advice? Our experts assist you in choosing the optimal solution for your production.
Kai Kleinevoß
Head of Sales Wirbalit®
kleinevoss@svs-schweisstechnik.de
+49 208 99 328 15