Switching Contacts

6.4.4 Switching Contacts

• Effects during switching operations

Figure 1 Fig. 6.7: Contact opening with arc formation schematic

Figure 1: Contact opening with arc formation (schematic)

• Influence of out-gasing from plastics

Figure 2 Fig. 6.9: Histogram of the contact resistance Rk of an electroplated palladium layer (3 μm) with and without hard gold flash plating (0.2 μm) after exposure with different plastic materials

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

Figure 2: Histogram of the contact resistance R_K of an electroplated palladium layer (3 μm) with and without hard gold flash plating (0.2 μm) after exposure with different plastic materials

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

• Influence of corrosive gases on the contact resistance

Figure 4 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 mV_DC,10 mA; Probing contact: Gold rivet

Figure 4: 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 mV_DC,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

Figure 5 Fig. 6.12: Material transfer under DC load a) Cathode; b) Anode.
Material: AgNi0.15; Switching parameters: 12V_DC, 3 A, 2x10⁶ operations

Figure 5: Material transfer under DC load a) Cathode; b) Anode.
Material: AgNi0.15; Switching parameters: 12V_DC, 3 A, 2x10⁶ operations

• • Arc erosion

Figure 6 Fig. 6.13: Arc erosion of a Ag/SnO₂ contact pair after extreme arcing conditions a) Overall view; b) Partial detail view

Figure 6: 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