Switchgear & Distribution Panels
Where aluminium feeders meet copper busbar — stable joints for decades, with an auditable mill certificate.
The problem you need to solve
In a low-voltage switchgear cabinet, the incoming aluminium feeder cable lands on a copper busbar through a bolted joint. IEC 61439-1 allows 70 K temperature rise at terminals at rated current. A direct Al/Cu contact builds an oxide film and begins galvanic corrosion; over a few years the junction shows as a hotspot on thermal imaging and drifts out of the temperature budget under summer peak load. Antioxidant paste can be re-applied every few years — but opening a maintenance window, documenting the work, and carrying the liability is a well-known pain in any serious facility (hospital, data centre, industrial plant).
How CUPAL solves it
CUPAL puts the whole transition into a single diffusion-bonded plate or washer: the aluminium side faces the cable lug or terminal, the copper side faces the busbar. The electrochemical driver of galvanic corrosion — two dissimilar metals sharing an electrolyte at the joint — is removed at the contact itself. No paste, no annual re-torque, no oxide surprises on the thermographic survey. The base material carries DIN 17007 / DIN 1787 designations (aluminium AL 99.5 / 3.0255, copper E1-Cu58 / 2.0065); EN 10204 2.2 with every shipment, EN 10204 3.1 on request. Manufacture runs under ISO 9001:2015; the parent group (HIDRA-MIX, Budapest) has been producing bimetal since 1991.
What this looks like in numbers
Where it fits in the cabinet
Four common points where the panel builder deals with an Al/Cu joint.
Incoming feeder → main busbar
The problem you need to solve. A three-phase aluminium feeder (e.g. 3×240 mm² Al) lands on the main copper busbar through a bolted lug. It is one of the heaviest-loaded joints in the cabinet for the IEC 61439-1 thermal budget.
How CUPAL solves it. A CUPAL transition plate between the lug and the bar. Al face to the lug, Cu face to the bar — standard M10/M12 hardware, spring washers. Cut to the existing bolt pattern.
Outgoing feeder: Cu busbar → Al cable to MCC
The problem you need to solve. The outgoing direction lands copper busbar on aluminium cable feeding a motor control centre or sub-distribution. Same Al/Cu bolted joint, often with stricter handover documentation.
How CUPAL solves it. A CUPAL washer between busbar and lug. One part, no extra tools, no paste — and the material ships with an EN 10204 certificate you can drop into the panel dossier.
N / PE equipotential bar
The problem you need to solve. In a multi-storey riser, aluminium neutral and PE conductors terminate onto the cabinet's copper bonding bar. Thermal cycling relaxes the bolted joint, oxide adds resistance.
How CUPAL solves it. A CUPAL transition plate between bonding bar and riser. The diffusion interface handles the thermal-expansion mismatch internally; the joint stays stable without re-torquing.
Brownfield retrofit
The problem you need to solve. A 10–20-year-old cabinet gets an Al feeder upgrade on capacity, but the original copper busbar stays. Off-the-shelf compression bimetal lugs rarely match the old bolt pattern or stack-up height.
How CUPAL solves it. A CUPAL plate cut to the existing pattern. Ships in 2–4 weeks from a DXF drawing, installs without structural modification.
Compared to alternatives
Four familiar approaches, measured on 10-year operating cost and fitting flexibility — for a cabinet with many joints.
| Approach | Initial joint behaviour | Maintenance | Lead time | 10-year TCO / joint |
|---|---|---|---|---|
| Cu lug + antioxidant paste | Acceptable, drifts over time | New paste + re-torque every 2–3 yrs | From stock | High (labour) |
| Specialty compression bimetal lug (imported) | Stable | None | 6–12 weeks, fixed geometry | Medium–high |
| Over-sized pure copper conductor | Excellent | None | 4–6 weeks | High (copper cost) |
| CUPAL custom-cut (EU) | Stable | None | 2–4 weeks, any geometry | Low |
FAQs from panel builders
Recommended CUPAL products
Applicable standards for this field
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