Relay and the surge current

When such high currents flow in two conductors 1-2 mm from each other, this will cause a force between the flexible contacts in an ordinary relay. Have you checked that this force does not cause significant bending of the flexible contact armature, which could cause movement at the contact point, which could cause large variations in the contact resistance.

Paul

It's the surface contact area that is important. You have to know what the current density is. If it's high enough, it will melt the contact metals at the contact points. If this fused area is large enough, the contacts may not separate when you want them to.

Al

try it ? Are these real pulses, or some Transient theory ? Measure the contact resistance (eg 5mOhms)

-jg

Paul Ke >

Thank you for the >

It seems logical that the size of the fused area and the mechanical strength of the contacts are related to the nominal current rating of the relay. So there should be some kind of a rule of how much t*I^2 the relay can stand depending on the nominal current rating. Do you know of such a rule?

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

My guess is that the force for a typical relay contact might be about

Paul

The simple estimate shows that the acting force should be at least at the order of several kg to produce any noticeable excursion in the 100us of time.

VLV