Sizing of connection contact plates

[mesa5]

If I'm designing two surfaces to transmit power when connected to two other surfaces, what are the equations governing the sizes of those surfaces in terms of current carrying ability and proper spacing in between? I'm sure I can start by making sure that their cross sectional area if equivalent to the wire being connected to them, and determining their spacing using Paschen's law, but I was wondering if there was a better analysis I should do.

 

[bacon4life]

What voltage & power levels are you thinking about? For low voltage (50V to 600V), insulation spacing distances are driven more by mechanical reasons than voltage breakdown. At medium and high voltage, insulation distances are more influenced by Pashcen's law. Be aware that instead of the operating voltage such as 12.5 kV, components are distances are based on the Basic Insulation Level (BIL), which is 95 kV for a circuit operated at 12.5 kV. The BIL takes into account the likely transients the circuit may experience.

Usually the surface area is much larger than the conductor. The link gives a typical value of 50A per square inch for large conductors.

http://books.google.com/books?id=Ec...age&q=amps per square inch connection&f=false

Other considerations include the amount of contact pressure and the heat dissipation characteristics of the surrounding material. Larger contact pressure reduces the contact resistance. NEMA type testing for transmission line conductors requires connectors to operate cooler than the connected cable.

 

[mesa5]

This would be ~50A @ 12 VDC.

For the heat dissipation I'm assuming you'd calculate the resistance of your connection plate, then determine the ohmic heat generated?

Is there a formula for contact pressure/contact resistance?

 

[Skogsgurra]

Why, at all, care about Paschen's law in a low voltage circuit? I don't understand from where such an idea can stem. Or is it 12 kV you mean instead of 12 V?

For the area and current carrying capacity, I recommend "Electrical Contacts" by Ragnar Holm, Ph. D.

Or have an electrical guy do the dimensioning for you. Just like I ask structural guys Before I do something to my house. There is a reason for our different specializations.

Gunnar Englund

http://www.gke.org

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