Brochure/Catalogue

Relay modules are used in a wide variety of industrial areas and environments.
The relays must therefore be adapted to the various tasks by selecting
suitable contact materials. The following applies: the load capacity of
the contacts for voltage, current, and power depends essentially on the
material used. To make the selection easier for you, we have compared
the most important characteristics of the contact materials
Criteria for the selection of the contact material:
• Welding tendency
• Burn-off resistance
• Contact resistance
Please obtain information when selecting a relay in this table:
Material Characteristics Recommended applications
Silver-nickel
• Higher welding tendency than AgSnO and AgCdO
• High burn-off resistance
• Lower contact resistance than AgSnO and AgCdO
• Mean material migration
• Low resistance to harmful gas atmospheres
• Suitable for low to high resistive and low inductive loads
(solenoid valves, fans, heaters)
• Standard contact material for a variety of relays
• Limited suitable for high inrush currents
• Suitable for loads > 12 V/10 mA or 5 V/100 mA
Silver-nickel flash gold plated
• Higher welding tendency than AgSnO and AgCdO
• High burn-off resistance (gold just storage protection)
• Lower contact resistance than AgSnO and AgCdO
• Mean material migration
• Low resistance to harmful gas atmospheres
• Suitable for low to high resistive and low inductive loads
(solenoid valves, fans, heaters)
• The flash gold plating is a storage protection, but offers no functional improvement to AgNi
• Limited suitable for high inrush currents
• Suitable for loads > 12 V/10 mA or 5 V/100 mA
Silver-nickel hard gold plated
• Very low resistance to burn-off
• Lowest contact resistance
• High resistance to harmful gas atmospheres
• Suitable for decoupling control inputs and other small resistive loads
• Suitable for loads > 1 V/1 mA and < 30 V/10 mA
• After switching loads > 30 V/100 mA, small powers can no longer be switched
reliably because the hard gold plating has been burned-off. Only the characteristics
of the base contact material AgNi still apply.
Silver-Tin-Oxide
• Lower welding tendency than AgNi und AgCdO
• High resistance to burn-off
• Average contact resistance
• Lower material migration than AgNi and AgCdO
• Very low resistance to harmful gas atmospheresn
• Suitable for medium to high resistive DC-loads and low up to medium inductive DC loads due
to low material migration. Thanks to the low tendency to weld, it is also well suited for loads
with higher inrush currents such as lamp loads, light capacitive loads, fluorescent tubes, etc.
• Suitable for loads > 12 V/100 mA
Silver-Cadmium-Oxide
• Lower welding tendency than AgNi
• High resistance to burn-off
• Average contact resistance
• Lower material migration than AgNi
• Very low resistance to harmful gas atmospheres
• Suitable for medium to high resistive and inductive AC loads, due to high burn-off resistance
• Suitable for loads > 12 V/100 mA
Tungsten
• Lowest welding tendency
• Very high resistance to burn-off
• Highest contact resistance
• Low material migration
• Suitable for loads with very high inrush currents of up to 165 A/20 ms or 800 A/200 μs
(e.g. lamp loads, capacitive loads, fluorescent tubes, switched-mode power supplies etc.)
• Often used as a pre-making contact in parallel to AgSnO contacts
Select contact materials suitable for the application
Information of various contact materials
• Material migration
• Resistance to harmful gas atmospheres
Silver
Gold
Nickel
Cadmium
Tin
Tungsten
A.92737920000
Selection guide
A
Information of various contact materials