the presence of the negative-sequence current
3I
2
.
The zero sequence detection algorithm is
recommended for IEDs used in directly or low
impedance earthed networks. It is based on the
zero sequence measuring quantities, a high value
of zero sequence voltage 3U
0
without the
presence of the zero sequence current 3I
0
.
For better adaptation to system requirements, an
operation mode setting has been introduced
which makes it possible to select the operating
conditions for negative sequence and zero
sequence based function. The selection of
different operation modes makes it possible to
choose different interaction possibilities between
the negative sequence and zero sequence based
algorithm.
A criterion based on delta current and delta
voltage measurements can be added to the fuse
failure supervision function in order to detect a
three phase fuse failure, which in practice is more
associated with voltage transformer switching
during station operations.
Breaker close/trip circuit monitoring TCSSCBR
The trip circuit supervision function TCSSCBR is
designed to supervise the control circuit of the
circuit breaker. The invalidity of a control circuit is
detected by using a dedicated output contact
that contains the supervision functionality.
The function operates after a predefined
operating time and resets when the fault
disappears.
8. Control
Synchrocheck, energizing check, and
synchronizing SESRSYN
The Synchronizing function allows closing of
asynchronous networks at the correct moment
including the breaker closing time, which
improves the network stability.
Synchrocheck, energizing check, and
synchronizing (SESRSYN) function checks that
the voltages on both sides of the circuit breaker
are in synchronism, or with at least one side dead
to ensure that closing can be done safely.
SESRSYN function includes a built-in voltage
selection scheme for double bus and 1½ breaker
or ring busbar arrangements.
Manual closing as well as automatic reclosing can
be checked by the function and can have different
settings.
For systems which are running asynchronous a
synchronizing function is provided. The main
purpose of the synchronizing function is to
provide controlled closing of circuit breakers
when two asynchronous systems are going to be
connected. It is used for slip frequencies that are
larger than those for synchrocheck and lower
than a set maximum level for the synchronizing
function.
Autorecloser for 3-phase operation
The autorecloser SMBRREC function provides
high-speed and/or delayed auto-reclosing for
single breaker applications.
Up to five three-phase reclosing attempts can be
included by parameter setting.
The autoreclosing function can be configured to
co-operate with a synchrocheck function.
Autorecloser for 1/3-phase operation STBRREC
The autoreclosing function provides high-speed
and/or delayed auto-reclosing for single breaker
applications.
Up to five reclosing attempts can be included by
parameter setting. The first attempt can be single-
and/or three phase for single-phase or multi-
phase faults respectively.
Multiple autoreclosing functions are provided for
multi-breaker arrangements. A priority circuit
allows one circuit breaker to close first and the
second will only close if the fault proved to be
transient.
The autoreclosing function can be configured to
co-operate with a synchrocheck function.
Bay control QCBAY
The Bay control QCBAY function is used together
with Local remote and local remote control
functions to handle the selection of the operator
place per bay. QCBAY also provides blocking
functions that can be distributed to different
apparatuses within the bay.
Breaker protection REQ650
1MRK 505 283-BEN -
Product version: 1.2
ABB 21
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