Page 763 - Industrial Power Engineering and Applications Handbook

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Relevant Standards

IEC Title IS BS
60298/1990 A.C metal enclosed switchgear and controlgear for rated 3427/1991 BS EN 60298/1996
voltages above 1kV and up to and including 52 kV
60050- I95/1998 Code of practice for earthing and protection against 3043/1991 BS 7430/1998
electric shocks BS IEC 60050-195

Relevant US Standards ANSI/NEMA and IEEE
_____
~ ~~ ~
AN S UIEEE- Guide for generator ground protection
37.101/1993
ANSUIEEE8 1/1983 Guide for measuring earth resistivity, ground impedance and earth surface potentials of a ground system. Part I:
Normal measurements
ANSI/IEEE-80/1991 Guide for safety in a.c. substation grounding
ANSI/IEEE-l42/1991 Grounding of industrial and commercial power systems (IEEE Green book)
ANSUIEEE Recommended practice for electric power distribution for industrial plants (IEEE Red book)
141/1993
ANSMEEE Recommended practice for electric power systems in commercial buildings (IEEE Grey book)
24 1/199 1
ANSUIEEE Recommended practice for protection and coordination of industrial and commercial power systems
242/1991 (IEEE. Buff book)
ANSUIEEE- Recommended practice for determining the electric power station ground potential rise and inductive
367/1987 voltage from a power fault
C2- 1997 National Electrical Safety code (NESC)

Notes
1 In the tables of Relevant Standards in this book while the latest editions of the standards are provided, it is possible that revised editions
have become available. With the advances of technology and/or its application, the updating of standards is a continuous process by
different standards organizations. It is therefore advisable that for more authentic references, readers should consult the relevant
organizations for the latest version of a standard.
2 Some of the BS or IS standards mentioned against IEC may not be identical.
3 The year noted against each standard may also refer to the year of its last amendment and not necessarily the year of publication.

List of formulae used w = width of strip or twice the diameter of the conductor
rod in cm
Resistance to ground: Q = -1 for strip and -1.3 for round conductor grounding

Plate grounding
Size of the grounding conductor
I
(22.1) s=L&
k (22.4)
p = resistivity of soil in Rm S = cross-sectional area of a bare ground conductor in
A = area of each side of the plate in m2
mm2
I = r.m.s. value of the ground fault current in amperes
Pipe or rod grounding K = a factor that would depend upon the material of the
conductor
R=- 100. p x [loge 7 t = duration of fault in seconds
R
1}
8x1
-
2n. I (22.2)
1 = length of pipe in cm Tolerable step voltage
d = internal diameter of pipe in cm.
0.116
Strip or conductor grounding Ea(50) 5 (6 . cs ' P\ + 000) x -
.Jt
loop for a 50 kg body (22.5)
R=- x log, - (22.3)
2x12 +QOhms
2n. 1 h.w 470, 5 (6 ' c, ' P? + 000) x -
0.157
1 = length of strip or rod in cm Ji
h = depth of strip or rod in cm for a 70 kg body (22.6)