Secondary System Supervision; Control; Current Circuit Supervision Ccsrdif; Fuse Failure Supervision Sddrfuf - ABB RED670 Product Manual

Line differential protection RED670 ANSI
Customized
Product version: 1.2
CVGAPC can also be used to improve phase selection for high
resistive ground faults, outside the distance protection reach,
for the transmission line. Three functions are used, which
measures the neutral current and each of the three phase
voltages. This will give an independence from load currents and
this phase selection will be used in conjunction with the
detection of the ground fault from the directional ground fault
protection function.

9. Secondary system supervision

Current circuit supervision CCSRDIF (87)

Open or short circuited current transformer cores can cause
unwanted operation of many protection functions such as
differential, ground-fault current and negative-sequence current
functions.
It must be remembered that a blocking of protection functions
at an occurrence of open CT circuit will mean that the situation
will remain and extremely high voltages will stress the
secondary circuit.
Current circuit supervision (CCSRDIF, 87) compares the
residual current from a three phase set of current transformer
cores with the neutral point current on a separate input taken
from another set of cores on the current transformer.
A detection of a difference indicates a fault in the circuit and is
used as alarm or to block protection functions expected to give
unwanted tripping.

Fuse failure supervision SDDRFUF

The aim of the fuse failure supervision function (SDDRFUF) is to
block voltage measuring functions at failures in the secondary
circuits between the voltage transformer and the IED in order to
avoid unwanted operations that otherwise might occur.
The fuse failure supervision function basically has three different
algorithms, negative sequence and zero sequence based
algorithms and an additional delta voltage and delta current
algorithm.
The negative sequence detection algorithm is recommended for
IEDs used in isolated or high-impedance grounded networks. It
is based on the negative-sequence measuring quantities, a high
value of voltage without the presence of the negative-sequence
current 3I .
2
The zero sequence detection algorithm is recommended for
IEDs used in directly or low impedance grounded networks. It
is based on the zero sequence measuring quantities, a high
value of voltage 3V without the presence of the residual
0
current 3I .
0
22
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.

10. Control

Synchrocheck, energizing check, and synchronizing SESRSYN
(25)
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,
25) 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 (25) function includes a built-in voltage selection
scheme for double bus and breaker-and-a-half 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
synchronism check and lower than a set maximum level for the
synchronizing function.
Autorecloser SMBRREC (79)
The autorecloser SMBRREC, 79 function provides high-speed
and/or delayed auto-reclosing for single or multi-breaker
applications.
Up to five three-phase reclosing attempts can be included by
parameter setting. The first attempt can be single-, two and/or
three pole for single pole or multi-pole faults respectively.
Multiple autoreclosing functions are provided for multi-breaker
arrangements. A priority circuit allows one circuit breaker to
1MRK505226-BUS D
ABB