Main Articel: [[Contact Physics – Formulas| Contact Physics – Formulas]]
*'''Constriction resistance'''
Re = D/2a
(Single spot contact according to Holm; circular touching spot between clean
contact surfaces)
Re = D/2Na
(Multi-spot contact according to Holm without influence between the N
individual spots)
Re = D/2 x E ai + 3B D/32N² x E E (sij) i = j
(Multi-spot contact according to Greenwood considering the influence between
the spots)
als bild?
*'''Contact resistance'''
RK = Re + Rf
*'''Path resistance'''
Rd = Rb + RK
*'''Contact resistance and contact force'''
R = 280D ³ E(F · r) K K
(According to Holm model for film-free spherical contact surfaces with plastic
deformation of the contact material; F < 1 N for typical contact materials) k
RK = 9000 D H/ FK
(According to Holm model for film-free spherical contact surfaces with plastic
deformation of the contact material; F > 5 N for typical contact materials)
*'''Dynamic contact separation''' (without considering magnetic fields caused by the current path)
FA 0,8 x I²
(Rule of thumb with F in N and I in kA)
*'''Contact voltage and max. contact temperature'''
T kmax 3200 UK
*'''Contact resistance at higher contact forces (according to Babikow)'''
R = cF -m K K
For F between 10 and 200 N K
c = material dependent proportionality factor
m = shape dependent exponent of the contact force
===6.4.3 Closed Contacts===