Electrical contacts overview ( switchgears )
To find the proper English terminology, try searching for "medium voltage switchgear glossary." You might also search for "medium voltage switchgear technical guide," "... design guide," or "... application guide." Instead of the word "guide" you could also try "handbook" or "manual." Switchgear is not "adjusted to" medium voltage, it is designed for medium voltage.

The best information about design details will probably be found in papers published by IEEE. It is expensive get access to IEEE papers unless you can get access through a university library. If you find an abstract for a paper that looks promising, you could try to find the author's company or university and get a copy from their web site.

You may also be able to find information about patented features using google.com/patents. If you look at a patent, be sure to look at the references listed in it. Some of the references may be accessible and useful.

You could try google.com/images. You will get a lot of unrelated images, but you may be able to scan through the thumbnails and spot something useful.

Finding the kind of information that you seem to be looking for requires trying a lot of different search alternatives.