ABB Relion 670 series - Page 227

Compensation for ground-return path for faults involving ground is done by setting the parameter
KN and KNAng where KN is the magnitude of the ground-return path and KNAng is the angle of the
ground-return path.
0 1
1
3
Z Z
KN
Z
-
=
×
IECEQUATION14023 V1 EN-US (Equation 53)
(
)
0 1
3 1
Z Z
KNAng ang
Z
-
=
×
EQUATION1807-ANSI V1 EN-US (Equation 54)
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-ground and phase-to-phase measuring loops can be time delayed individually by
setting the parameter
tPG and tPP respectively. To release the time delay, the operation mode for
the timers, OpModetPG and OpModetPP , has to be set to On . This is also the case for
instantaneous operation. In instantaneous case, the timers
tPG 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-ground and phase-to-phase timers are triggered by the
respective measuring loop pickup signals.
•
Timers linked : Start of any of the phase-to-ground or phase-to-phase loops will trigger both
the phase-to-ground or phase-to-phase timers.
•
Internal start : Phase-to-ground and phase-to-phase timers are triggered by the INTRNST
input.
• Start from PhSel : The phase-to-ground 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-ground and phase-to-phase timers are triggered by the EXTNST input.
The function can be blocked in the following ways:
• activating of input BLOCK blocks the whole function
• activating of the input BLKZ (fuse failure) blocks all output signals
• activating of the input BLKZMTD blocks the delta based time domain algorithm
1MRK 502 066-UUS B Section 7
Impedance protection
221
Technical manual