ABB Relion 670 Series Applications Manual page 309

1MRK 511 401-UEN Rev. K
elements must always be set with a safety margin of 10 to 20%, depending on the system
operating conditions.
Pay special attention to the dissymmetry of the measuring quantities when the function is
used on long untransposed lines, on multicircuit lines and so on.
The settings of negative sequence, zero sequence and delta algorithm are in percent of the
base voltage and base current for the function. Common base IED values for primary current
IBase ), primary voltage ( UBase ) and primary power ( SBase ) are set in Global Base Values
(
GBASVAL . The setting GlobalBaseSel is used to select a particular GBASVAL and used its base
values.
14.2.3.2 Setting of common parameters
Set the operation mode selector
The voltage threshold
USealIn< below the minimum operating voltage that might occur during emergency
conditions. We propose a setting of approximately 70% of
The drop off time of 200 ms for dead phase detection makes it recommended to always set
SealIn to On 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
requirements. The mode selector enables selecting interactions between the negative
sequence and zero sequence algorithm. In normal applications, the
UNsINs for selecting negative sequence algorithm or UZsIZs 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
UZsIZs OR UNsINs both negative and zero sequence based algorithms are activated and
mode
working in an OR-condition. Also in mode
algorithms are activated and the one that has the highest magnitude of measured negative or
zero sequence current will operate. If there is a requirement to increase the security of the fuse
failure function
and zero sequence algorithms are activated and working in an AND-condition, that is, both
algorithms must give condition for block in order to activate the output signals BLKU or BLKZ.
14.2.3.3 Negative sequence based
The relay setting value
be set lower than the value that is calculated according to equation 177.
Bay control REC670
Application manual
Operation to On to release the fuse failure function.
USealIn< is used to identify low voltage condition in the system. Set
OpMode has been introduced for better adaptation to system
OpMode can be selected to UZsIZs AND UNsINs which gives that both negative
3U2> is given in percentage of the base voltage UBase and should not
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UBase .
OpMode is set to UZsIZs OR UNsINs or OptimZsNs . In
OptimZsNs both negative and zero sequence
Section 14
Secondary system supervision
M13683-9 v9
OpMode is set to either
M13683-17 v9
303