Grounding Techniques

[mull982]

Hello All!

I wanted to get some help on grounding techniques in an electrical distribution system. I guess my question is when, and at which points in the system to use ground rods etc... For instance we have our main utility transformer (130KV to 4160KV) which is resistance grounded. Now obviously there are several other transformers throughout the plant (for 480 MCC's) however I was wondering, technically could the nuetrals of these transformers all be connected back to the neutral on the main transformer or do each of the transformers have to be individually grounded. Some of the 480V transformers are also resistance grounded so I am assuming they are grounded at the transformer, but I was just wondering what the general practice was, and if you could just have the one ground path off the main utility transformer for the whole system.

I guess the main concept I'm trying to understand is grounding in an electrical distribution system, when, where, and on what types of equiptment.

Thanks for your help everyone!

mull982

 

[steve66]

This is off the cuff, but if you connected the ground of your smaller transformers to the ground of the main transformer, wouldn't that defeat the resistance grounding?

Transformers are normally ran delta to wye, so there usually isn't a neutral on the primary side, although there is probably a ground. I'm not sure what you would land the primary ground wire on if it's resistance grounded???