I cannot dispute the cautions voiced by Trumpy. Heck, for me, "high voltage" is anything over 500 volts!
I recently purchased a former power company truck. This truck was built with a special compartment for a "hot stick," a tool used with assorted attachemnts for operating high voltage equipment. I looked at such sticks and their prices are most impressive! And I am sure that these are not the only tools used with such equipment.
In other words, the equipment necessary to work with high voltage equipment is of such a specific use, ad high cost, that it almost has to be employer-supplied, and by a large employer at that!
The power companies have multiple apprentice programs, with different qualifications for differing voltage levels. Quite simply put, it taked a fair amount of specific education just to learn what the pieces are; and even the most basic task can be an involved process. You just don't have to throw a switch!
I don't know why you asked your question. If you have been tasked to deal with some piece of equipment, you are to be commended for seeking information. That information is most likely available from whoever manufactured the gear, or built the installation. Failing that, given your circumstances, the power company may agree to let you participate in their training program.
Considering this age of DIY mischief-makers, and suit-happy lawyers, you are sure to encounter some resistance, as folks will rightly want to know why you want to learn this stuff. Our friends in "Earth First!" have shown a particular desire to attempt to disrupt utilities. (One such attempt involved a propane torch attempt to drop a power pylon).
Be well, be safe, and don't be afraid to say "NO".
