Re: -48 V used in telecommunications
I deal with it every day. The equipment is divided into two distinct categories: Isolated ground planes, and integrated ground planes.
Isolated ground plane equipment has the battery return isolated from the equipment chassis and is intended to be installed in a "single-point isolated ground plane".
Integrated ground plane equipment may or may not have the battery return isolated from the chassis and is intended to be installed in the "integrated ground plane" or multi-point grounded.
It all revolves around a ground bar (MGB) installed inside a "ground window", and how the two ground planes are integrated from a common DC power supply.
Most telephone companies have their own engineering and installation practices for grounding and DC power schemes. They are all based off of Bellcore TR-NWT-000295, which is available from Telcordia for about $300. ANSI also has a document availible for sale and is similar to Bellcore, but not as well written IMO. But they are all proprietarily documents (code word for closely gaurded secret)
If you will send me your e-mail address via PM, I can send you a engineering practice that I wrote for a very large telephone company.
[ November 19, 2003, 01:32 PM: Message edited by: dereckbc ]