Main Articel: [[Physical Effects in Sliding and Connector Contacts| Physical Effects in Sliding and Connector Contacts]]
====6.4.6 General Rules for Dimensioning of Contacts====
Main Articel: [[General Rules for Dimensioning of Contacts| 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) 0.05 - 0.08 N/A
(Silver – Metal oxide contacts)
Power switches 0.1 - 0.2 N/A
Connectors > 30 cN/contact element
(Gold coating)
Connectors > 50 cN/contact element
(Silver coating)
Connectors > 1 N/contact element
(Tin coating)
*'''General Rules for Dimensioning of Contact Rivets'''
bild
*'''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)
Fig. 6.18: Failure probability of a contact as a
function of the voltage (according to Kirchdorfer);
Ag/Ni10; 10 mA
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
===6.4.7 Contact Spring Calculations===