More info
Description / Abstract:
This guide is primarily concerned with outdoor ac substations,
either conventional or gas-insulated. Distribution, transmission,
and generating plant substations are included. With proper caution,
the methods described herein are also applicable to indoor portions
of such substations, or to substations that are wholly indoors.
No attempt is made to cover the grounding problems peculiar to
dc substations. A quantitative analysis of the effects of lightning
surges is also beyond the scope of this guide.
Purpose
The intent of this guide is to provide guidance and information
pertinent to safe grounding practices in ac substation design.
The specific purposes of this guide are to:
a) Establish, as a basis for design, safety limits of potential
differences that can exist in a substation under fault conditions
between points that can be contacted by the human body.
b) Review substation grounding practices with special reference
to safety, and develop safety criteria for design.
c) Provide a procedure for the design of practical grounding
systems, based on these criteria.
d) Develop analytical methods as an aid in the understanding and
solution of typical voltage gradient problems.
e) Provide benchmarks cases to compare the results of IEEE Std
80™ equations to commercially available software programs.
The concept and use of safety criteria are described in Clause 1
through Clause 8, practical aspects of designing a grounding system
are covered in Clause 9 through Clause 13, and procedures and
evaluation techniques for the grounding system assessment (in terms
of safety criteria) are described in Clause 14 through Clause 20.
Supporting material is organized in Annex A through Annex H.
This guide is primarily concerned with safe grounding practices
for power frequencies in the range of 50 Hz to 60 Hz. The problems
peculiar to dc substations and the effects of lightning surges are
beyond the scope of this guide. A grounding system designed as
described herein will, nonetheless, provide some degree of
protection against steep wave front surges entering the substation
and passing to earth through its ground.