2300V and above motor grounding requirements
2300V and above motor grounding requirements
(OP)
On a particular project that I am on we have a number of medium voltage motors that I will supply an additional #4/0AWG bare copper ground that will bolt on the the motor frame and connect to nearest grounded building steel. Does anyone know if there is an IEEE standard that recommends motors greater than 460V to have these grounding requirements? I was told by a co-worker that it is standard practice to provide an additional ground in addition to the ground in the feeder cable to motors that are 2300volts and above. Any suggestions, references, personal experiences with this is greatly appreciated.
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Jacobs Engineering Group Inc.
1041 East Butler Road
Post Office Box 5456
Greenville South Carolina 29606-5456
864·676·6458 Phone 864·676·4789 Fax
E-mail: jason.buda@jacobs.com
Jason W. Buda
Electrical and Control Systems Department
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RE: 2300V and above motor grounding requirements
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Jacobs Engineering Group Inc.
1041 East Butler Road
Post Office Box 5456
Greenville South Carolina 29606-5456
864·676·6458 Phone 864·676·4789 Fax
E-mail: jason.buda@jacobs.com
Jason W. Buda
Electrical and Control Systems Department
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
RE: 2300V and above motor grounding requirements
I haven't ever heard any discussion of whether or not motor frames were required to be grounded... only what size ground conductor to be used.
I'll look for some references.
RE: 2300V and above motor grounding requirements
4/0-AWG exposed bare copper (often somewhat more corrosion-resistant 7-strand) and heavy IEEE-837 connectors are boilerplate in quite a few engineering designs. It allows for ready visual inspection of equipment condition, and limits touch-step potential during ground-fault incidents. It also generally represents a smaller portion of circuit per-unit cost where more costly shielded cables fill a given raceway, compared to, say, 600V THWN. {It’s cheap insurance, so to speak.}
As evidenced by thousands of miles of 5-35kV overhead distribution, higher-reactance ground returns are suitable for effective protective-device operation.
RE: 2300V and above motor grounding requirements
~10kA for 100cycles=1.6667seconds
~20kA for 30cycles=0.5seconds
~100kA for 1cyle=0.0167seconds
which appears to be practical and more than enough for many grounding purposes.
RE: 2300V and above motor grounding requirements
RE: 2300V and above motor grounding requirements
Are you an archaeologist? You've dug up a thread over four yers oild to ask a question that isn't really even related to the orignal content. Well done for using the search to find it, but don't be afraid to start a new thread to ask your question.
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