Negative Sequence Based - ABB REC650 Applications Manual

Section 9
Secondary system supervision
9.2.3.3
174
The settings of negative sequence, zero sequence and delta algorithm are in percent of the
global base voltage and global base current for the function, VBase and IBase
respectively.
The voltage threshold VSealInPU is used to identify low voltage condition in the system.
Set VSealInPU below the minimum operating voltage that might occur during emergency
conditions. We propose a setting of approximately 70% of the global parameter VBase.
The drop off time of 200 ms for dead phase detection makes it recommended to always set
SealIn to Enabled since this will secure a fuse failure indication at persistent fuse fail when
closing the local breaker when the line is already energized from the other end. When the
remote breaker closes the voltage will return except in the phase that has a persistent fuse
fail. Since the local breaker is open there is no current and the dead phase indication will
persist in the phase with the blown fuse. When the local breaker closes the current will start
to flow and the function detects the fuse failure situation. But due to the 200 ms drop off
timer the output BLKZ will not be activated until after 200 ms. This means that distance
functions are not blocked and due to the "no voltage but current" situation might issue a
trip.
The operation mode selector OpModeSel has been introduced for better adaptation to
system requirements. The mode selector makes it possible to select interactions between
the negative sequence and zero sequence algorithm. In normal applications the
OpModeSel is set to either V2I2 for selecting negative sequence algorithm or V0I0 for zero
sequence based algorithm. If system studies or field experiences shows that there is a risk
that the fuse failure function will not be activated due to the system conditions, the
dependability of the fuse failure function can be increased if the OpModeSel is set to V0I0
OR V2I2 or OptimZsNs. In mode V0I0 OR V2I2 both the negative and zero sequence based
algorithm is activated and working in an OR-condition. Also in mode OptimZsNs both the
negative and zero sequence algorithm are activated and the one that has the highest
magnitude of measured sequence current will operate. If there is a requirement to increase
the security of the fuse failure function OpModeSel can be selected to V0I0 AND V2I2,
which gives that both negative and zero sequence algorithm is activated working in an
AND-condition, that is, both algorithms must give condition for block in order to activate
the output signals BLKV or BLKZ.

Negative sequence based

The relay setting value 3V2PU is given in percentage of the base voltage VBase and should
not be set lower than according to equation 86.
1MRK 511 286-UUS A
Application manual