Compensation for earth -return path for faults involving earth is done by setting the
parameter
KN
and
KNAng
where
KN
is the magnitude of the earth -return path and
KNAng
is the argument of the earth-return path.
0
1
1
3
Z
Z
KN
Z
-
=
×
IECEQUATION14023 V1 EN
(Equation 35)
( )
0
1
arg
3
1
Z
Z
KNAng
Z
-
=
×
EQUATION1580 V1 EN
(Equation 36)
where
Z0
is the complex zero sequence impedance of the line in Ω/phase
Z1
is the complex positive sequence impedance of the line in Ω/phase
The phase-to-earth and phase-to-phase measuring loops can be time delayed
individually by setting the parameter
tPE
and
tPP
respectively. To release the time
delay, the operation mode for the timers,
OpModetPE
and
OpModetPP
, has to be set
to
On
. This is also the case for instantaneous operation. In instantaneous case, the
timers
tPE
and
tPP
need to be set as zero.
The operate timers triggering input depends on the parameter
ZnTimerSel
setting. The
parameter
ZnTimerSel
can be set to:
•
Timers separated
: Phase-to-earth and phase-to-phase timers are triggered by the
respective measuring loop start signals.
•
Timers linked
: Start of any of the phase-to-earth or phase-to-phase loops will
trigger both the phase-to-earth or phase-to-phase timers.
•
Internal start
: Phase-to-earth and phase-to-phase timers are triggered by the
INTRNST
input.
•
Start from PhSel
: The phase-to-earth and phase-to-phase timers are triggered by
the
STCND
and
LDCND
inputs. Each of the two inputs consist binary status
information related to the six measuring loops. Hence if any of the measuring
loop status is high in both two inputs
STCND
and
LDCND
, then the timers will be
triggered. In case when
LoadEnchMode
is
off
then only
STCND
enables the timer.
It is not recommended to use this timer setting for the Zone
instance where
LoadEnchMode
is off.
•
External start
: Phase-to-earth and phase-to-phase timers are triggered by the
EXTNST
input.
1MRK502052-UEN B
Section 7
Impedance protection
183
Technical manual
Summary of Contents for Relion REG670
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