First, define electrical duty
Rated current is only one of the inputs. Resistive, inductive, motor, lamp or capacitor load can create very different inrush current and arc in the same rated current.
Record AC or DC voltage, steady and inrush current, power factor or time constant, number of disconnects and connections, and target life.
Compare alloy families by duty
AgNi provides a good balance of conductivity, wear, and manufacturability for many relays and control equipment. AgSnO₂ is considered at higher loads and where welding and arc erosion are important.
Pure silver and some composites are suitable for low-energy circuit; AgCdO can only be used within a valid design framework and with consideration of alloy limitations.
Consider contact mechanics and environment in evaluation
Contact force, jump, opening speed, wiper movement, alignment, humidity, dust and corrosive gases have a direct effect on the result.
The same alloy can perform differently by changing the geometry, connection method or thermal path.
Validate on the final set
The catalog guide is useful for initial screening, not final verification. The sample should be tested under electrical, mechanical, thermal and environmental load.
The criteria of resistance, temperature rise, welding, erosion and failure should be defined before the test.
Practical summary
Any alloy, geometry, or corrective action decisions must be verified by controlled drawing and representative testing on the final assembly.
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