RatVoltW2TraB
M12541-298 v3
The rated voltage (kV) of the secondary side (non-line side = low voltage side) of the power
transformer B.
ClockNumTransB
M12541-301 v2
This is the phase shift from primary to secondary side for power transformer B. The phase
shift is given in intervals of 30 degrees, where 1 is -30 degrees, 2 is -60 degrees and so on. The
parameter can be set within the range 0 – 11.
ZerSeqCurSubtr
M12541-307 v4
The elimination of zero sequence currents in the differential protection can be set
On/Off. In
case of a power transformer in the protected zone, where the zero sequence current cannot be
transformed through the transformer, that is, in the great majority of cases, the zero sequence
current must be eliminated.
ZerSeqCurSubtr must be set On if there is a transformer in the zone. The zero sequence
currents are then subtracted from all current terminals.
CrossBlockEn
M12541-310 v3
The possibility of cross-blocking can be set
On/Off. The meaning of cross-blocking is that the
2
nd
and 5
th
harmonic blocking in one phase also blocks the differential function of the other
phases. It is recommended to enable the cross-blocking if a power transformer is included in
the protection zone, otherwise not.
IMaxAddDelay
M12541-313 v4
IMaxAddDelay is set as a multiple of IBase. The current level, under which a possible extra
added time delay (of the output trip command), can be applied. The possibility for delayed
operation for small differential currents is typically used for lines with a (minor) tapped
transformer somewhere in the protected circuit and where no protection terminal of the multi-
terminal differential protection is applied at the transformer site. If such a minor tap
transformer is equipped with a circuit breaker and its own local protection, then this
protection must operate before the line differential protection to achieve selectivity for faults
on the low voltage side of the transformer. To ensure selectivity, the current setting must be
higher than the greatest fault current for faults at the high voltage side of the transformer.
AddDelay
M12541-316 v2
The possibility of delayed operation for small differential currents can be set
On/Off.
CurveType
M12541-321 v3
This is the setting of type of delay for low differential currents.
tMinInv
M12541-324 v4
This setting limits the shortest delay when inverse time delay is used. Operation faster than
the set value of
tMinInv is prevented.
If the user-programmable curve is chosen the characteristic of the curve is defined by
equation
Section 6
1MRK 505 343-UEN B
Differential protection
132
Application manual
Содержание Relion 670 series
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