Difference between revisions of "Contact Physics – Formulas"
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===6.4.2 Contact Physics – Formulas=== | ===6.4.2 Contact Physics – Formulas=== | ||
| − | *'''Constriction resistance''' <math> | + | *'''Constriction resistance''' <math>R_e = \rho/2a</math> |
(Single spot contact according to Holm; circular touching spot between clean | (Single spot contact according to Holm; circular touching spot between clean | ||
contact surfaces) | contact surfaces) | ||
| − | <math> | + | <math>R_e = \rho/2Na</math> |
(Multi-spot contact according to Holm without influence between the N | (Multi-spot contact according to Holm without influence between the N | ||
individual spots) | individual spots) | ||
Revision as of 18:17, 26 March 2014
6.4.2 Contact Physics – Formulas
- Constriction resistance
(Single spot contact according to Holm; circular touching spot between clean
contact surfaces)
(Multi-spot contact according to Holm without influence between the N
individual spots)
(Multi-spot contact according to Greenwood considering the influence between
the spots)
- Contact resistance
RK = Re + Rf
- Path resistance
Rd = Rb + RK
- Contact resistance and contact force
(According to Holm model for film-free spherical contact surfaces with plastic
deformation of the contact material; Fk < 1 N for typical contact materials)
(According to Holm model for film-free spherical contact surfaces with plastic
deformation of the contact material; Fk > 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 FA in N and I in kA)
- Contact voltage and max. contact temperature
Tkmax 3200 UK
- Contact resistance at higher contact forces (according to Babikow)
RK = cF -m K
For FK between 10 and 200 N c = material dependent proportionality factor m = shape dependent exponent of the contact force
