ABB RELION REX640 Technical Manual page 608

Protection functions
For body weight of 70kg:
where
C
is the surface layer derating factor
s
ρ
is the surface material resistivity in Ω·m
s
ρ is the resistivity of the earth beneath the surface material in Ω·m
If no protective surface layer is used, then
The equations of IEEE Std 80-2013 are in IFPTOC-function modelled with following
simplified equation, with only one setting
With setting
voltage magnitude can be adjusted. For body weight of 70kg,
then
In case
is used to scale the touch voltage and earth potential rise requirements defined
in standard IEEE80 into corresponding earth-fault current requirements. When
Operating curve type = "Inverse time IEEE80" is selected, then the protection
operate time as a function of estimated effective earth-fault current
into account the effect of settings
according to equation below:
Example numerical values of the permissible touch voltage U
corresponding earth-fault current requirements as a function of the fault duration
according to standard IEEE80 are shown in table below.
Table 629: Numerical example of the values of the permissible touch voltages U
as a function of the fault duration t
into corresponding permissible earth-fault current values. The numerical values
assume body weight of 70 kg,
157. Conversion is made with parameter R
608
IEEE multiplier the operate time as a function of estimated touch
IEEE multiplier equals 157.0.
Operation principle = "EF current based", setting Maximum earthing Ris
C ρ
=1 and
s
IEEE multiplier :
Reduction factor and Enable harmonics ) is
according to standard IEEE80 converted
f
C ρ ρ = 0 Ω·m, then IEEE multiplier equals
=1, =
s s
, which is the setting
Emax
1MRS759142 F
(Equation 123)
ρ .
=
s
(Equation 124)
C ρ ρ = 0 Ω·m,
=1, =
s s
(taking
(Equation 125)
converted into
Tp
Maximum
Technical Manual
t
f
Tp
REX640