Difference between revisions of "General Rules for Dimensioning of Contacts"
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Revision as of 15:34, 7 April 2014
6.4.6 General Rules for Dimensioning of Contacts
- Recommended Minimum Contact Forces at Slightly Sliding Contact Make:
Gold | 0.03 N |
Silver | 0.1 N |
Tungsten | 0.5 N |
- Contact Force Recommendations:
Signal relays | ≥ 3 cN |
AC power relays | ≥ 20 cN |
Automotive relays | ≥ 20 cN |
Motor switches (Contactors) (Silver – Metal oxide contacts) |
0.05 - 0.08 N/A |
Power switches | 0.1 - 0.2 N/A |
Connectors (Gold coating) |
≥ 30 cN/contact element |
Connectors (Silver coating) |
≥ 50 cN/contact element |
Connectors (Tin coating) |
≥ 1 N/contact element |
- General Rules for Dimensioning of Contact Rivets
Dimensioning | Solid Rivets (1) | Composite Rivets (2) |
---|---|---|
a : d | 1.5 : 1 bis 2.5 : 1 | 2 : 1 bis 2.5 : 1 |
a : b | 2.5 : 1 bis 10 : 1 | 3 : 1 bis 5 : 1 |
c : b | ≥ 1 : 1 | ≥ 1 : 1 |
b : s | ≥ 2 : 1 | |
smin | ≈ 0.3 mm |
- Head diameter for electrical loads
For AC currents: | approx. 1 – 1.5 A/mm² |
For 1 A | min. 2 mm head diameter |
10 A | approx. 3 – 3.5 mm head diameter |
20 A | approx. 5 mm head diameter |
For DC currents: | approx. 0.5 – 0.8 A/mm² |
- Head radius R for electrical loads
for I < 1 A | R ≈ 1,5 mm |
I = 6 A | R ≈ 5 mm |
I = 10 A | R ≈ 10 mm |
I = 20 A | R ≈ 15 mm |
- Failure Probability of Single and Double (Bifurcated) Contacts (according to Thielecke)
Contact force[N] | Single contact | |||
---|---|---|---|---|
Ag | AuNi 5, Pt | Ag | AuNi 5, Pt | |
0.04 | 1 x 10-4 | 2 x 10-8 | ||
0.1 | 2 x 10-3 | 4 x 10-5 | 8 x 10-5 | 8 x 10-9 |
0.2 | 1 x 10-4 | 8 x 10-6 | 4 x 10-6 | 4 x 10-8 |
0.3 | 5.5 x 10-6 | 1.5 x 10-6 | 1.8 x 10-7 | 3.2 x 10-10 |
Figure 1 Fig. 6.18: Failure probability of a contact as a function of the voltage (according to Kirchdorfer); Ag/Ni10; 10 mA
Figure 2 Fig. 6.19: Failure probability of a contact as a function of the current (according to Kirchdorfer); Ag/Ni10; F = 0.45 N; U = 24 V