grounding mesh : which equiptment

[dalas]

hi,


at a 150 kV conventional substation (air insulation) that has LA, CVT, DS+E, DS, CB, CT, Tx, which one of these apparatus should be connected to grounding mesh?

and, which one should not be ?

thank you.

 

[WindTurbinesAreFine]

I'm not sure what a DS is, but we connect essentially everything to the grounding grid. Failing to bond above grade metallic objects within the substation to the below grade grid could produce unsafe touch potentials.

From your list of equipment, I would connect all that you have listed (except DS since I am not familiar with that).

If you have sensitive communications equipment, you may have to do something different.

 

[rcw retired EE]

Connect everything in your list. I assume DS = Disconnect Switch and DS+E = Switch with Earthing switch.

 

[magoo2]

Yes, connect all your acronyms to the GM!

 

[jghrist]

Yes, connect all your acronyms to the GM!

Except your CBWUGN (capacitor bank with ungrounded neutral).

 

[dalas]

Opss.. sorry for the acronyms.

and, thank you for replies

LA = Lightning Arrester, CVT = Capacitive Voltage Tx, DS = Disconnecting Switch (E=Earthing), CB = Circuit Breaker, CT = Current Tx.

Next question is :

How about Lightning Arrester (or Surge Arrester?) ??
it is recommended to connect them with grounding mesh?

sorry, for repeating this question.

 

[ScottyUK]

Normally a lightning arrestor is designed to shunt the impulse from a lightning strike to ground before it wipes out the equipment it is protecting. So you have to ask... if it ain't connected to the earthing mat, what function does it serve?


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If we learn from our mistakes I'm getting a great education!

 

[rterickson]

I would ground all your steel bus and equipment support structures too.

 

[racobb]

Along with what Scotty says, if it is designed to have a ground, then I would make sure it had one.

Alan

 

[cuky2000]

The purpose of the equipment ground is to maintain the similar potential between the equipment metals and the ground potential. Therefore, all equipment chassis and metal structures should be grounded as required per codes and engineering guidelines.

There is a controversial practice to ground sensitive electronic equipment to minimize "noise" problems. In the ANSI marketplace, is mandatory to ground all equipment.

There are a few exceptions such as series compensated cap bank steel platforms energized above ground potential. This is usually mounted on insulators and enclosed inside a fence to avoid direct contact to unauthorized personnel.

See sample enclosed link:

http://www.ptd.siemens.de/images/Fig4_series_compensation.jpg