ABB REQ650 User Manual

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 OpMode 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 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
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 OpMode can be selected to UZsIZs AND UNsINs, 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
BLKU or BLKZ.
9.2.3.3 Negative sequence based
The relay setting value 3U2> is given in percentage of the base voltage UBase and
should not be set lower than according to equation
72.
3 2
3 2
100U
U
UBase
>= ×
EQUATION1519 V3 EN
(Equation 72)
where:
3U2 is the maximal negative sequence voltage during normal operation conditions, plus a margin of
10...20%
UBase is setting of the global base voltage for all functions in the IED.
The setting of the current limit 3I2< is in percentage of global 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 73.
Section 9 1MRK 505 291-UEN A
Secondary system supervision
176
Application manual

ABB REQ650 Specifications

General

Brand	ABB
Model	REQ650
Category	Protection Device
Language	English