Hello JBUDA54,
There is a paper that addresses neutral-grounding-resistor selection specifically. I'll add a link to it below.
Ground-Fault Detection, Charging Current and Neutral-Grounding Resistor Selection
I would suggest, however, that if the resistors are intact, their replacement may...
I have often seen the term "earth leakage" define current flow that is below that of the protective relay's earth-fault pick-up setting. In this case, however, because the description is in regard to a relay, I believe the terms refer to the same thing.
I am not sure what "LGR" refers to. A...
I know that this post is fairly old, but it caught my eye when it popped up in a related Google search. I’d like to comment on zazmat’s post.
I am not sure that one thing can be electrically smaller than another.
Resistance grounding is more and more common today than in the past...
I've added a link below directing you to a document that will have some useful information for you raisinbran.
Ground-Fault Detection, Charging Current and Neutral-Grounding Resistor Selection
The paper addresses your enquiry in detail.
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Cory Anderson
http://startco.ca/
I have heard of several installations using a continuous-rated neutral-grounding resistor, and an appropriate zigzag transformer, to allow the system to operate with a ground fault. In either case, as Marmite suggested, ground-fault protection on downstream devices should be set to operate...
You are correct vennivivi- in general the minimum neutral-grounding-resistor let-through current should be equal to, or larger than the system charging-current. The document linked below contains detailed information about the selection of a neutral-grounding resistor.
Ground-Fault Detection...
Hello Simmi123,
The SE-105 Ground-Fault Ground-Check Monitor is an analog relay with a ground-fault circuit low-pass filter having a frequency response of 25 to 400 Hz, and may be prone to harmonic frequencies developed by the VFD. The SE-325 Neutral-Grounding-Resistor Monitor could also be...
An SE-525 Earth-Leakage and Ground-Integrity Monitor may work here...
SE-525 Earth-Leakage and Ground-Integrity Monitor
A PDF version of the manual is available here.
Are 8-A output contacts sufficient?
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Cory Anderson
http://startco.ca/
There is an online schematic diagram showing how to high-resistance ground the neutral of a delta transformer as dpc suggested. I'll add the link below.
Implementing Resistance Grounding on Ungrounded Systems
You could skip the zigzag if you're grounding the neutral of a wye-connected...
It just occurred to me that I may have misinterpreted your question nightfox1925. There are also a series of Startco ground-check monitors that may be applicable (SE-105, -107, -134C, -135). I was considering your inquiry more from a transformer-grounding perspective rather than a...
The Startco relays you speak of are called neutral-grounding-resistor monitors. There is no mention of a grounding scheme here but... the SE-330-series monitor could be configured for a system with a solid ground (which is essentially a grounding resistor with a very, very small impedance)...
Yes PnCTech44, you're in good hands with Eng-Tips. I am yet another electrical engineer involved with protective relaying that is a member of this forum. The folks here are very knowledgeable and active. I'm confident that any kind of networking you're looking to accomplish can be done so...
I too am unaware of any such regulation. I did as you did majesus and looked through my copy of CSA M421-00 Use of Electricity in Mines - I found nothing.
I understand that there are many coal mines in that region - in that regard a limitation on voltage seems to make sense. It seems to me...
Hello Goldyvb,
Jim (lansford) is right about the United States MSHA requirements. You can read a little more about them at the following link.
http://www.msha.gov/30cfr/18.47.htm
Is this system in the United States? I’ll also add a link to a white paper that may be helpful...
I found the following excerpt in my copy of the “Canadian Electrical Code Part I: Safety Standard for Electrical Installations.”
10-1108 Conductors used with neutral-grounding devices
1. The conductor connecting the neutral-grounding device to the neutral point of the transformer shall be
(c)...
