Why NC relay can't carry as much current?

[cupoftea]

Hi,
Do you know why the NC version of this relay is only rated to 7A...but the NO version is rated to 16A?

https://www.azettler.com/pdfs/az9422.pdf

 

[KlausST]

Hi,

I don´t know. So I can only guess.

I guess it´s because fo the mechanical force that is applied to the contacts.
The NC contact is forced CLOSED by a spring ... with about linear behaviour: distance vs force
The NO contact is forced CLOSED by the magnet (coil, core) ... with extremely unlinear behaviour.
Thus I expect the magnetic force is much higher than the spring force.

Klaus