Earthing of Mobile Equipment

[goldyvb]

Hi All,

I am doing the preliminary design for a mobile mining unit and trying to work out what to do with the earthing. The unit is running on tank tracks and moves about 30m every 3-4 days. Onboard there is a trailing cable running from an external cable reeler to a 6.6kV RMU (which also feeds another mobile unit that follows it) and then a transformer which supplies the onboard MCC with a running load of about 800kW (DOL and VSD driven motors and auxiliaries).

I am looking for advice from anyone else that may have undertaken something similar to ensure that the earthing, touch and step potentials for the unit are adequate. Any advice would be gratefully received.

Thanks

Goldyvb

 

[lansford]

Dear Gold,
In the USA, mining is governed by the government agence MSHA which requires that the power for portable or mobile equipment be resitance grounded with a 25 amp grounding resitor. Common voltages for the utilzation equipment are 4160 and 7200 volts since the loads are large such as draglines and electric power shovels. There is also a requirement that the grounding conductor be continuously monitored.(Ground check relay usually with a pilot wire in the trailing cable). Look in the IEEE green book for more information as well as other references.
Jim

 

[CoryA]

Hello Goldyvb,

Jim (lansford) is right about the United States MSHA requirements. You can read a little more about them at the following link.

[URL unfurl="true"]http://www.msha.gov/30cfr/18.47.htm[/url]

Is this system in the United States? I’ll also add a link to a white paper that may be helpful.

[URL unfurl="true"]http://www.startco.ca/library/papers/Ground-Fault Paper.pdf[/url]

The paper talks about the selection of neutral-grounding resistors, ground-fault protection for remote mining machines, ground-conductor monitoring, and preferred ground-conductor monitor characteristics. Page 5 of the paper talks a little bit about Canadian CSA standards and American MSHA standards.

You may be attempting to ground something other than a remote mining machine, but I think this paper contains relevant information with regard to your query.

---
Cory Anderson

http://startco.ca/