CuCr25 Vacuum Interrupter Contact

CuCr25 is the high-conductivity copper-chromium grade, 25% chromium in a copper matrix, and the most common contact material for general-purpose medium-voltage vacuum interrupters. The copper matrix carries continuous current with low resistance; the chromium phase handles the arc during interruption, suppresses welding, and keeps chopping current low. CuCr25 is typically produced by casting or vacuum induction melting, which gives a fine, evenly distributed chromium phase and good conductivity.

We supply CuCr25 contacts to drawing for vacuum circuit breakers and vacuum contactors across the standard MV range. For higher interruption ratings and severe duty, see CuCr50 Vacuum Interrupter Contact. For the contact geometry options (AMF / RMF / butt), see CuCr Contact Disc.

Specifications

Property	Value
Material Grade	CuCr25 (Chromium 23–27 wt%, copper balance)
Production Process	Cast / vacuum induction melted
Form	Disc / AMF / RMF / custom geometry (per drawing)
Dimensions	Per drawing
Tolerance	Per drawing
Density	≥8.25 g/cm³ per GB/T 26867-2011
Electrical Conductivity	≥28 MS/m (≈48% IACS) per GB/T 26867-2011
Hardness	≥70 HB per GB/T 26867-2011
Oxygen Content	≤0.050 wt% per GB/T 26867-2011
Nitrogen Content	≤0.003 wt% per GB/T 26867-2011
Mounting Interface	Brazed to copper / copper-alloy stem per drawing

Exact certified properties for your lot are available with material documentation on request.

Applications

• Make-and-break contacts for general-purpose MV vacuum circuit breakers (7.2–40.5 kV class)
• Vacuum contactor contacts for motor and capacitor switching
• Distribution-class vacuum interrupter assemblies
• Replacement contacts for installed VCB fleets

Technical Notes

CuCr25's value is conductivity. At 25% chromium, the copper matrix is continuous and carries continuous current with low contact heating. The reason CuCr25 is the default for distribution-class breakers where the duty is dominated by continuous current with occasional fault interruption. Cast or melted CuCr25 gives a fine chromium distribution, which matters for consistent arc behavior across the contact face.

The trade-off versus higher-chromium CuCr50 is interruption behavior. CuCr25 carries current better, but CuCr50 chops at lower current and resists welding better under severe duty. For most distribution breakers and contactors, CuCr25 is the right balance; step up to CuCr50 when interruption rating, capacitor or generator switching, or cycle count justifies it.

Low dissolved gas content is essential. The contact sits inside a sealed vacuum bottle, and gas released under arc heating degrades the vacuum. CuCr25 supplied for VI service is processed to keep oxygen and nitrogen within the GB/T 26867-2011 limits.

Sourcing & OEM

Custom CuCr25 contacts to your drawing are routine. Specify the geometry (disc, AMF, RMF), dimensions, and stem interface; contact us for a project-specific quote.