Switching Contacts

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6.4.4 Switching Contacts

  • Effects during switching operations

Fig. 6.7 Contact opening with arc formation (schematic)

  • Influence of out-gasing from plastics

Fig. 6.9: Histogram of the contact resistance R of an electroplated K palladium layer (3 μm) with and without hard gold flash plating (0.2 μm) after exposure with different plastic materials

Fig. 6.10: Contact resistance with exposure to out-gasing from plastics as a function of numbers of operations at 6 V ,100 mA: 1 Silicon containing plastic; 2 Plastics with strongly out-gasing DC components; 3 Plastics with minimal out-gasing components

  • Influence of corrosive gases on the contact resistance

Fig. 6.11: Distribution of cumulative frequency H of the contact resistance for solid contact rivets after 10 days exposure in a three-component test environment with 400 ppb each of H2S, SO2 and NO2 at 25°C, 75% RH; Contact force 10cN; Measuring parameters: ≤ 40 mVDC,10 mA; Probing contact: Gold rivet

Fig. 6.8: Influences on contact areas in relays


  • Contact Phenomena under the influence of arcing Matertia
  • Material transfer

Fig. 6.12: Material transfer under DC load a) Cathode; b) Anode. 6 Material: AgNi0.15; Switching parameters: 12VDC, 3 A, 2x10 operations

  • Arc erosion

Fig. 6.13 Arc erosion of a Ag/SnO2 contact pair after extreme arcing conditions a) Overall view; b) Partial detail view

  • Contact welding

Fig. 6.14: Micro structure of a welded contact pair (Ag/SnO2 88/12 - Ag/CdO88/12) after extremely high current load. a) Ag/SnO2 88/12; b) Ag/CdO88/12


References

References