ABB RELION REX640 Technical Manual page 610

Protection functions
89 with setting
resistance encountered in protected feeder.
Group
a
b
c
d
e1
e2
It is important to note, that:
1.
2.
3.
Consider next the following example with
IEEE80":
Example 3. Inverse time operation of IFPTOC, when
current based" and
Figure 347
minimum operate time 100 ms and maximum operate time of 5000 ms. Setting
multiplier is 500 and setting Maximum earthing Ris is 10 ohms. Reduction factor =
1.0. For illustrating the operating speed requirement of protection, limits of earth
potential rise durations defined in Finnish national Electrical Safety Regulations 89
scaled the into corresponding earth-fault current requirements using the maximum
earthing resistance R
feeder are shown for reference.
610
Maximum earthing Ris in primary ohms i.e. the maximum earthing
Highest allowed EPR values [V] converted into corresponding
permissible fault current, I
disconnected within time t [sec]
(750 V/
(2000 V/
(3000 V/
(500 V/
(750 V/
(1000 V/
Minimum effective earth-fault current magnitude (considering the effect of
Reduction factor ), which must be exceeded for the function to start, is defined
EF current Str Val . It is important to set this value according to
with setting
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.
IDMT stage Max Op Tm setting user can define maximum allowed operate
With
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 = "EF current
Operating curve type = "Inverse time IEEE80" is selected.
based" and
Maximum earthing Ris is needed to scale the touch voltage
Setting
and earth potential rise requirements defined in standard IEEE80 into
corresponding earth-fault current requirements.
Reduction factor considers the fact that only part of the earth-
Setting
fault current (I
F
earthing and touch voltages.
Operating curve type = "Inverse time IEEE80" is selected, then
When
setting UTp multiplier is not effective.
Operating curve type = "Inverse time IEEE80" is illustrated in
. Start value for operation is set to be 0.02*In (2 A). IFPTOC is set to have
Emax
Fp
Maximum earthing Ris )/√t
Maximum earthing Ris )/√t
Maximum earthing Ris )/√t
Maximum earthing Ris )/√t
Maximum earthing Ris )/√t
Maximum earthing Ris )/√t
) will flow back through "remote" earth and introduces
Operating curve type = "Inverse time
Maximum earthing Ris ) encountered in protected
(setting
1MRS759142 F
[A],when earth fault is automatically
Maximum
Operation principle = "EF-
Technical Manual
IEEE
REX640