ABB RELION REX640 Technical Manual page 622

Protection functions
into IFPTOC. The numerical values assume body weight of 70 kg,
Ω·m, then
Fault duration t
0.05
0.10
0.20
0.50
1.00
2.00
5.00
10.00
In some countries, safety during an earth fault is defined in terms of highest
allowed earth potential rise (EPR) as a function of fault duration. As an example,
in Finnish national Electrical Safety Regulations 89 define highest allowed earth
potential rise (EPR) as a function of fault duration as shown in table below.
Table 634: Highest allowed EPR value based on Electrical Safety Regulations 89
Group
a
b
c
d
e1
e2
The regulations of
is set to equal the highest allowed voltage value, for example for group d,
multiplier = 500.
It is important to note, that:
1.
2.
3.
622
IEEE multiplier equals 157.
[sec.]
f
Highest allowed EPR [V], when earth-fault is automatically
disconnected within time
750V/√
2000V/√
3000V/√
500V/√
750V/√
1000V/√
Table 634
Minimum effective touch-voltage magnitude (considering the effect of
Reduction factor ), which must be exceeded for the function to start, is defined
Touch Vol Str Val . It is important to set setting Touch Vol Str Val
with setting
according to required protection sensitivity.
IDMT stage Min Op Tm setting user can define minimum allowed operate
With
time for IFPTOC i.e. this is the minimum allowed operate time of IFPTOC.
With IDMT stage Max Op Tm setting user can define maximum allowed operate
time for IFPTOC i.e. this is the maximum allowed operate time of IFPTOC
although IDMT timer would define slower operate time.
Parameter defining maximum earthing resistance, setting
earthing Ris must be always set in case Operation principle = "Touch
voltage based" and
selected. Setting
earth-fault current value into corresponding touch voltage or earth
potential rise value.
Permissible touch voltage, U
702
496
351
222
157
111
70
50
t [sec]
t
t
t
t
t
t
are implemented into IFPTOC. Setting
Operating curve type = "Inverse time IEEE80" is
Maximum earthing Ris is needed to scale the estimated
1MRS759142 F
C ρ
=1,
s s
[V]
Tp
IEEE multiplier
IEEE
Maximum
Technical Manual
ρ = 0
=
REX640