Conductor Material Selection for MV Switchgear
The current path through MV switchgear, from cable termination through the breaker contacts to the outgoing bus, runs through conductors that have to balance three things: conductivity, mechanical strength, and arc tolerance at exposed segments. No single material wins on all three, so most switchgear current paths combine materials. This guide explains how to choose conductor material and which product to source for each segment.
For the full range, see Conductive Rods & Conductors.
The Three-Way Trade-Off
| Material | Conductivity | Mechanical strength | Arc tolerance | Best for |
|---|---|---|---|---|
| Pure copper (C11000/C10100) | Highest | Lowest | Low | Main current path, bus runs |
| Aluminum bronze (C95400) | Low (~10-15% IACS) | High | Moderate | Sliding/wear conductor segments |
| Copper tungsten (CuW) | Moderate | High | Highest | Arc-exposed segments |
Most MV switchgear designs use copper for the bulk current path and switch to bronze or CuW only at segments that need wear resistance or arc tolerance.
Main Current Path: Copper
For the bus and main conductor runs, pure copper is the default, highest conductivity keeps continuous-current heating manageable.
- Copper Conductive Rod: ETP copper (C11000) for general use, OFC copper (C10100) where impurity content matters. Rod stock for in-house machining or as-supplied conductor.
- Copper Conductor Element: machined copper conductor segments (stepped, flanged, threaded) ready for assembly.
ETP vs OFC: for MV switchgear, ETP C11000 is the standard choice. OFC's marginally higher conductivity rarely matters at switchgear frequencies and currents.
Wear-Exposed Segments: Aluminum Bronze
Where a conductor sees mechanical wear, sliding contacts, rotating interfaces, repeated assembly, aluminum bronze outlasts copper at the cost of conductivity:
- Aluminum Bronze Rod: C95400 rod for sliding-contact and mechanical-duty conductors. Size up the cross-section to compensate for the lower conductivity.
Moving Contact Path: Compound Design
The moving side of an MV breaker connects the operating mechanism to the moving contact, carrying full current plus arc current at the contact face:
- Moving Contact Conductor: typically copper conductor with a CuW tip brazed at the contact face. Combines copper's conductivity with CuW's arc resistance.
Arc-Exposed Segments: Copper Tungsten
Where a conductor segment is directly arc-exposed, CuW is the answer, see the CuW Series for conductive rods and conductor elements in copper tungsten. Compound conductors (copper + CuW segment, brazed) put CuW only where the arc strikes.
Selection Path
- Bulk current path, no wear, no arc? → Copper Conductive Rod or Copper Conductor Element
- Sliding or rotating wear? → Aluminum Bronze Rod
- Moving contact path? → Moving Contact Conductor
- Arc-exposed segment? → CuW conductor (see CuW Series)
Compound Conductors
For designs combining materials, a copper bus with a CuW segment at the arc interface, or a copper conductor with an aluminum bronze sliding section. We produce brazed compound conductors as a single sub-assembly. Specify the full geometry and the material for each segment.
Related Reading
- Bronze Component Selection Guide: bronze alloy selection
- Copper Tungsten Component Selection Guide: CuW components
- Conductive Rods & Conductors (Category): full product range