ABB RELION REX640, Техническое руководство, Страница: 621 / 1960

(Equation 128)
For body weight of 70 kg:
(Equation 129)
where
C
s
is the surface layer derating factor
ρ
s
is the surface material resistivity in Ω·m
ρ is the resistivity of the earth beneath the surface material in Ω·m
If no protective surface layer is used, then
C
s
=1 and ρ
s
= ρ.
The equations of IEEE Std 80-2013 are in IFPTOC function modelled with following
simplified equation, with only one parameter IEEE multiplier:
(Equation 130)
With setting
IEEE multiplier operate time as a function of estimated touch voltage
magnitude can be adjusted. For body weight of 70 kg,
C
s
=1,
ρ
s
=
ρ = 0 Ω·m, then
IEEE multiplier equals 157.0.
In IFPTOC, the protection operate time
t as a function of estimated touch voltage
according to standard IEEE80 follows equation below:
(Equation 131)
Example numerical values of the permissible touch voltage U
Tp
as a function of the
fault duration t
f
according to standard IEEE80 are shown in
Table 633
. Values in
Table 633
assume body weight of 70 kg,
C
s
=1,
ρ
s
=
ρ = 0 Ω·m, then IEEE multiplier
equals 157.0.
Table 633: Numerical example of the values of the permissible touch voltages U
Tp
as a function of the fault duration t
f
according to standard IEEE80 programmed
1MRS759142 F Protection functions
REX640
Technical Manual
621