Basic requirements for contact materials:
1. good electrical and thermal conductivity;.
2. good resistance to fusion welding.
3. good resistance to electrical wear and tear properties.
4. good mechanical properties and welding properties
5. chemical stability
6. low gas content.
The properties and uses of each material are shown in the table:
| No. | Material | Performance characteristics | Main areas of application |
| 1 | Ag | High conductivity, low strength and hardness, low and stable contact resistance. | Micro switches for radio and communication and small current electrical appliances, etc. |
| 2 | FAg(AgNi0.15) | Add a small amount of alloying elements in silver to form silver alloy, refine the grain of the silver matrix, improve the strength of the material, resistance to fusion welding and resistance to electrical abrasion, and at the same time has the advantages of high conductivity and low contact resistance of pure silver. | It is suitable for low-voltage appliances with operating current below 10A, such as general-purpose relays, thermal protectors, timers, etc., and can be replaced by it in almost all applications of sterling silver. |
| 3 | AgNi | With high electrical conductivity, low contact resistance low and stable, in the DC open and close, the material transfer is less than pure silver. Resistance to fusion welding and resistance to electrical abrasion is average, usually paired with silver graphite. Using advanced extrusion technology, nickel particles are distributed in fibre form, which significantly improves the material performance. | Widely used in small and medium current AC and DC relays, command switches, contactors, optical switches, thermostats and timers for washing machines. |
| 4 | AgCdO | Adopting advanced sintering and extrusion process, CdO plasmas are diffusely distributed in the silver matrix, and under the action of electric arc, cadmium oxide is violently decomposed and evaporated to cool the surface of the contact, which plays a role in reducing the energy of electric arc and quenching the arc. The material has high resistance to welding and electrical wear resistance, low and stable contact resistance. | It is the most widely used low-voltage contact material, used in a large number of medium and large-capacity relays, contactors, AC and DC switches and small and medium-capacity circuit breakers, especially suitable for medium and large-capacity AC contactors. |
| 5 | AgSnO2 | AgSnO2 material has excellent and stable anti-melting welding and good resistance to arc erosion. In the current range of 500 ~ 3000A, AgSnO2 has a better resistance to arc erosion than AgCdO, in the lamp and capacitive loads, AgSnO2 than AgCdO, AgNi clearly show better resistance to fusion welding, in the AC resistive loads, AgSnO2 than AgCdO has a slightly higher contact resistance, but in the DC circuit 13.5V or less lamp / motor loads (e.g. automotive relays) applications, but exhibits low and stable resistance values. Under DC conditions, AgSnO2 has lower material transfer compared to AgCdO. | Widely used in medium and large capacity AC contactors (e.g. CJ20, CJ40, 3TF series, etc.), high power AC switches (more than 50kW), DC contactors, AC (DC) power relays, automotive electrical appliances, and small and medium capacity low voltage circuit breakers. |
| 6 | AgZnO | It has the characteristics of anti-melting welding, good resistance to electric abrasion, low and stable contact resistance, short arc ignition time, high breaking performance and strong resistance to high current impact. Compared with AgCdO contact material, AgZnO material has better resistance to turn-on fusion welding, and more ideal resistance to breaking arc erosion under the condition of 3000-5000A breaking current. | Mainly used in small and medium-capacity low-voltage circuit breakers with rated current within 200A, such as DZ15 series moulded case circuit breakers, DZ15L series earth leakage circuit breakers, etc. Certain large-capacity switches also use AgZnO materials, such as ME universal circuit breakers. |
| 7 | AgC | Due to the very high melting point of graphite, AgC series contact materials have excellent resistance to fusion welding (no fusion welding even under short-circuit current). Low contact resistance. | Widely used in high current, low voltage AC and DC automatic circuit breakers, starters, line protection switches, fault current protection switches, railway signal relays and other fields. Pairing with silver-nickel, anti-melt welding performance is improved, and can be applied to moulded case and universal circuit breakers, small and medium current contactors, microswitches and so on. |
| 8 | AgW | It has both the good electrical conductivity and easy processability of silver, and the high melting point, high hardness, arc erosion resistance, anti-melting welding, and less material transfer characteristics of tungsten. Its most important feature is its ability to withstand high-current arcs. | It can be applied to various universal circuit breakers, moulded case circuit breakers, heavy duty AC and DC contactors and other switching appliances. |
| 9 | AgNiC | Combines the advantages of silver-nickel and silver-graphite | Widely used in universal circuit breakers, such as DW45 and other intelligent universal circuit breakers |
| 10 | AgWC | Compared with silver tungsten, it is not easy to oxidise, has low and stable contact resistance and better resistance to fusion welding. | Mainly used in a variety of higher current circuit breakers and other switching devices, such as a variety of universal circuit breakers, moulded case circuit breakers, vacuum contactors, heavy duty AC and DC contactors. |
Post time: Jun-11-2024