Does anybody here know of equipment and procedures how to repair or change glass insulators on a live 230kV OH line.
Which safety rules should be considered
There is a book called "Live Line Work Practices" published by Alexander Publications, 177 Riverside Avenue #922, Newport Beach, CA 92663, ph. 800-992-3031,
This book has procedures on all types of live line work, including what you're looking for.
After reviewing the procedures in this book, you can identify what tools you will need and they are available thru AB Chance.
Since you (and your workers) have never done this, you need to practice this over and over in a training yard simulating actual conditions until everyone is proficient in this work.