Negative Sequence Based - ABB REG670 Applications Manual

Section 14
Secondary system supervision
14.2.3.3
474
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 OpMode has been introduced for better adaptation to
system requirements. The mode selector enables selecting interactions between the
negative sequence and zero sequence algorithm. In normal applications, the OpMode
is set to either 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 OpMode is set to
UZsIZs OR UNsINs or OptimZsNs. In mode UZsIZs OR UNsINs both negative and
zero sequence based algorithms are activated and working in an OR-condition. Also
in mode OptimZsNs both negative and zero sequence 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
OpMode can be selected to UZsIZs AND UNsINs which gives that both negative 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.

Negative sequence based

The relay setting value 3U2> is given in percentage of the base voltage UBase and
should not be set lower than the value that is calculated according to equation 261.
U 2
 
3 U 2 100
UBase 3
EQUATION1519 V5 EN
where:
U2 is the maximal negative sequence voltage during normal operation conditions, plus a margin of
10...20%
UBase is the base voltage for the function according to the setting GlobalBaseSel
The setting of the current limit 3I2< is in percentage of parameter IBase. The setting of
3I2< must be higher than the normal unbalance current that might exist in the system
and can be calculated according to equation 262.
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
1MRK 502 071-UEN -
(Equation 261)
Application manual