There are many hand books available in pdf format for free download in Department of energy web site - DOE, as such there is no index, but you can search through search engines. These handbooks are for basic knowledge.
Coming to electrical network one protection guide can be downloaded from

http://www.schneider-electric.com/sites/corporate/en/home.page

 

Hey,

pls check http://free.electricalbooks.co.cc/ , it's also having a lots of links to free engineering books, especially for electrical and electronics engineering.

 

You can visit the "Technical Publications" pages Schneider Electric web site. You will find lots of first class technical papers that you can download for free. Here's the link

http://www.schneider-electric.com/s...ical-publications/technical-publications.page