Difference between revisions of "Contact Physics – Formulas"
From Electrical Contacts
(→6.4.2 Contact Physics – Formulas) |
(→6.4.2 Contact Physics – Formulas) |
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===6.4.2 Contact Physics – Formulas=== | ===6.4.2 Contact Physics – Formulas=== | ||
| − | *'''Constriction resistance''' <br /> | + | *'''Constriction resistance''' <br />R<sub>e</sub> = D/2a |
(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) | ||
| − | + | R<sub>e</sub> = D/2Na | |
(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) | ||
| − | + | R<sub>e</sub> = D/2 x E ai + 3B D/32N² x E E (sij) i = j | |
(Multi-spot contact according to Greenwood considering the influence between | (Multi-spot contact according to Greenwood considering the influence between | ||
the spots) | the spots) | ||
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*'''Contact resistance and contact force''' <br />R<sub>K</sub> = 280D ³ E(F · r) K | *'''Contact resistance and contact force''' <br />R<sub>K</sub> = 280D ³ E(F · r) K | ||
(According to Holm model for film-free spherical contact surfaces with plastic | (According to Holm model for film-free spherical contact surfaces with plastic | ||
| − | deformation of the contact material; F < 1 N for typical contact materials) | + | deformation of the contact material; F<sub>k</sub> < 1 N for typical contact materials) |
| − | + | R<sub>K</sub> = 9000 D H/ FK | |
(According to Holm model for film-free spherical contact surfaces with plastic | (According to Holm model for film-free spherical contact surfaces with plastic | ||
| − | deformation of the contact material; F > 5 N for typical contact materials) | + | deformation of the contact material; F<sub>k</sub> > 5 N for typical contact materials) |
| − | *'''Dynamic contact separation''' (without considering magnetic fields caused by the current path) <br /> | + | *'''Dynamic contact separation''' (without considering magnetic fields caused by the current path) <br />F<sub>A</sub> 0,8 x I<sup>2</sup>(Rule of thumb with F<sub>A</sub> in N and I in kA) |
| − | *'''Contact voltage and max. contact temperature''' <br />T kmax 3200 | + | *'''Contact voltage and max. contact temperature''' <br />T<sub>kmax</sub> 3200 U<sub>K</sub> |
| − | *'''Contact resistance at higher contact forces (according to Babikow)''' <br />R = cF -m | + | *'''Contact resistance at higher contact forces (according to Babikow)''' <br />R<sub>K</sub> = cF -m K |
For F between 10 and 200 N K | For F between 10 and 200 N K | ||
c = material dependent proportionality factor | c = material dependent proportionality factor | ||
Revision as of 14:38, 20 January 2014
6.4.2 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
RK = 280D ³ E(F · r) K
(According to Holm model for film-free spherical contact surfaces with plastic deformation of the contact material; Fk < 1 N for typical contact materials) RK = 9000 D H/ FK (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 F between 10 and 200 N K c = material dependent proportionality factor m = shape dependent exponent of the contact force
