ABB RET670 Product Manual page 21

ABB
Transformer protection RET670
Pre-configured
Product version: 1.1
VSGGIO can be controlled from the menu or
from a symbol on the single line diagram
(SLD) on the local HMI.
Single point generic control 8 signals
SPC8GGIO
The Single point generic control 8 signals
(SPC8GGIO) function block is a collection of
8 single point commands, designed to bring
in commands from REMOTE (SCADA) to
those parts of the logic configuration that do
not need complicated function blocks that
have the capability to receive commands (for
example, SCSWI). In this way, simple
commands can be sent directly to the IED
outputs, without confirmation. Confirmation
(status) of the result of the commands is
supposed to be achieved by other means,
such as binary inputs and SPGGIO function
blocks.
Scheme communication
Scheme communication logic for residual
overcurrent protection ECPSCH
To achieve fast fault clearance of earth faults
on the part of the line not covered by the
instantaneous step of the residual overcurrent
protection, the directional residual
overcurrent protection can be supported with
a logic that uses communication channels.
In the directional scheme, information of the
fault current direction must be transmitted to
the other line end. With directional
comparison, a short operates time of the
protection including a channel transmission
time, can be achieved. This short operate
time enables rapid autoreclosing function
after the fault clearance.
The communication logic module for
directional residual current protection
enables blocking as well as permissive under/
overreaching schemes. The logic can also be
supported by additional logic for weak-end
infeed and current reversal, included in
Current reversal and weak-end infeed logic
for residual overcurrent protection Current
reversal and weak-end infeed logic for
1MRK 504 091-BEN B
residual overcurrent protection (ECRWPSCH)
function.
Current reversal and weak-end infeed logic
for residual overcurrent protection
ECRWPSCH
The Current reversal and weak-end infeed
logic for residual overcurrent protection
ECRWPSCH is a supplement to Scheme
communication logic for residual overcurrent
protection ECPSCH.
To achieve fast fault clearing for all earth
faults on the line, the directional earth-fault
protection function can be supported with
logic that uses communication channels.
The 670 series IEDs have for this reason
available additions to scheme communication
logic.
If parallel lines are connected to common
busbars at both terminals, overreaching
permissive communication schemes can trip
unselectively due to fault current reversal.
This unwanted tripping affects the healthy
line when a fault is cleared on the other line.
This lack of security can result in a total loss
of interconnection between the two buses. To
avoid this type of disturbance, a fault current
reversal logic (transient blocking logic) can
be used.
Permissive communication schemes for
residual overcurrent protection, can basically
operate only when the protection in the
remote terminal can detect the fault. The
detection requires a sufficient minimum
residual fault current, out from this terminal.
The fault current can be too low due to an
opened breaker or high positive and/or zero
sequence source impedance behind this
terminal. To overcome these conditions,
weak end infeed (WEI) echo logic is used.
Logic
Tripping logic SMPPTRC
A function block for protection tripping is
provided for each circuit breaker involved in
the tripping of the fault. It provides the pulse
prolongation to ensure a trip pulse of
Issued: June 2010
21