ground loop impedance

[lquadros]

Hi,
Does it always referes to AC systems when the term ground loop impedance is mentioned or this exists with DC systems? Is there DC grounding and does it involve impedance?

 

[dereckbc]

Re: ground loop impedance

Not exactly sure what you are asking. AC loop impedance testers and Meggars measure the AC impedance on the ground electrode system with a test frequency from 140-to-190 Hz. So it is an impedance at the test frequency applied.

DC ground systems, if you are referring to a ground electrode system use the same test equipment. It is still an AC impedance. The actual DC resistance is some what lower.

Is that what you are after?

Edit:

If you are referring to the EGC impedance of a branch or feeder circuit, the test instruments (like an Idea Sure Test) use the AC line voltage and frequency to measure the AC impedance at 60 Hz.

If you are talking about a DC power plant and want to measure the DC frame ground (AC EGC equivalent) resistance, you would use a special Digital Low Resistance Ohmmeter (DRLO), and measure the resistance between the return circuit and frame ground conductor at the device under test. DVM ohmmeters will not work with any accuracy.

[ March 09, 2004, 11:01 AM: Message edited by: dereckbc ]