View source for General Rules for Dimensioning of Contacts

===6.4.6 General Rules for Dimensioning of Contacts===

*'''Recommended Minimum Contact Forces at Slightly Sliding Contact Make:'''

{| class="twocolortable" style="text-align: left; font-size: 12px;width:40%"
|-
|Gold      
|0.03 N
|-
|Silver    
|0.1 N
|-
|Tungsten  
|0.5 N
|-
|}


*'''Contact Force Recommendations:'''

{| class="twocolortable" style="text-align: left; font-size: 12px;width:40%"
|-
|Signal relays     
|&ge; 3 cN
|-
|AC power relays   
|&ge; 20 cN
|-
|Automotive relays  
|&ge; 20 cN
|-
|Motor switches (Contactors)<br />(Silver – Metal oxide contacts)
|0.05 - 0.08 N/A
|-
|Power switches  
|0.1 - 0.2 N/A
|-
|Connectors<br />(Gold coating)
|&ge; 30 cN/contact element
|-
|Connectors<br />(Silver coating)
|&ge; 50 cN/contact element
|-
|Connectors<br />(Tin coating)
|&ge; 1 N/contact element
|}


*'''General Rules for Dimensioning of Contact Rivets'''

[[File:General Rules for Dimensioning of Contact Rivets.jpg|left|General Rules for Dimensioning of Contact Rivets]]
{| class="twocolortable" style="text-align: left; font-size: 12px;width:100%"
|-
!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      
|&ge; 1 : 1
|&ge; 1 : 1
|-
|b : s      
|
|&ge; 2 : 1
|-
|s<sub>min</sub>     
|
|&#8776; 0.3 mm
|}


*'''Head diameter for electrical loads'''

{| class="twocolortable" style="text-align: left; font-size: 12px;width:40%"
|-
|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'''

{| class="twocolortable" style="text-align: left; font-size: 12px;width:40%"
|-
|for I < 1 A     
|R &#8776; 1,5 mm
|-
|I = 6 A    
|R &#8776; 5 mm
|-
|I = 10 A    
|R &#8776; 10 mm
|-
|I = 20 A    
|R &#8776; 15 mm
|}


*'''Failure Probability of Single and Double (Bifurcated) Contacts''' (according to Thielecke)


{| class="twocolortable" style="text-align: left; font-size: 12px;width:100%"
|-
!Contact force[N]     
!colspan="4" style="text-align:center"|'''Single contact'''
|-
!    
!Ag
!AuNi 5, Pt
!Ag
!AuNi 5, Pt
|-
|0.04   
|
|1 x 10<sup>-4</sup>
|
|2 x 10<sup>-8</sup>
|-
|0.1   
|2 x 10<sup>-3</sup>
|4 x 10<sup>-5</sup>
|8 x 10<sup>-5</sup>
|8 x 10<sup>-9</sup>
|-
|0.2
|1 x 10<sup>-4</sup>
|8 x 10<sup>-6</sup>
|4 x 10<sup>-6</sup>
|4 x 10<sup>-8</sup>
|-
|0.3
|5.5 x 10<sup>-6</sup>
|1.5 x 10<sup>-6</sup>
|1.8 x 10<sup>-7</sup>
|3.2 x 10<sup>-10</sup>
|}


<div class="multiple-images">
<figure id="fig:Failure probability of a contact as a function of the voitage">
[[File:Failure probability of a contact as a function of the voitage.jpg|left|Failure probability of a contact as a function of the voltage (according to Kirchdorfer); Ag/Ni10; 10 mA]]
</figure>

<figure id="fig:Failure probability of a contact as a function of the current">
[[File:Failure probability of a contact as a function of the current.jpg|left|Failure probability of a contact as a function of the current (according to Kirchdorfer); Ag/Ni10; F<sub>k</sub> = 0.45 N; U = 24 V]]
</figure>
</div>
<div class="clear"></div>

<xr id="fig:Failure probability of a contact as a function of the voitage"/> Fig. 6.18: Failure probability of a contact as a function of the voltage (according to Kirchdorfer); Ag/Ni10; 10 mA

<xr id="fig:Failure probability of a contact as a function of the current"/> 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

==References==
[[Application Tables and Guideline Data for Use of Electrical Contact Design#References|References]]