To dereckbc

[paul]

I see you are a Telcom power engineer. I've been wondering lately about something. Grounding in the CO's. With all the redundant grounding happening, this has got to produce all sorts of grounding loops. I have to ground the AC at the main, every panel in the building, every transformer, ATS, water main, generators, rectifiers, ground rings, ground wells, etc. I also have to pull grounds in every conduit. I see nothing but ground loops all over these buildings. Doesn't this cause ground loops that can interfere with the switch as well as the AC electrical equipment???

 

[don_resqcapt19]

Re: To dereckbc

Paul,
Are you saying that you have multiple grounded to grounding (white to green) connections in the building? That would be a code violation and a safety hazard.
Don

 

[paul]

Re: To dereckbc

All those grounds, as we call them more like bonding, go back to the building MGB or Master Ground Bar.

 

[dereckbc]

Re: To dereckbc

Paul, sorry to be slow to respond, I have been in Lost Wages and Maui for vacation.

A CO has two ground planes, Integrated Ground Plane, and Isolated Ground Plane.

The Integrated Ground Plane is one big loop, a good one. Everything is bonded together to form a equipotential ground plane like a grid. Like any grid the high frequency impedance is very low between any two points, so any voltage developed by circulating currents is well below minimum operating thresholds. The equipment is not isolated from structural steel so lightning and fault currents will flow.

The Isolated Ground Plane is a completely different animal. All the equipment is isolated from building steel, raceways, concrete, etc. The equipment frames and power supplies (DC Plant frame & return bus, UPS return if isolated) are single point grounded to a MGB serving the plane. The point is to prevent any lightning or outside fault currents from flowing in the Isolated ground plane. No current, no voltage potential differences or noise.

Hope that helps... Dereck