4. Fundamental technological aspects

4.1 Contact

Switchgear is primarily a connecting device, which may or may not let current through depending on whether the contacts are open or closed.

These electrical contacts therefore play a fundamental role in the construction and performance of devices, in particular :

• contact resistance, and hence the resulting local heating, must remain low and without any noticeable change over time; this is due to the fact that the current only passes through the few points that are actually in contact and free...