Trip-Circuit Supervision; Self-Supervision; Current Circuit Supervision; Protection Communication And Supervision - ABB RED615 Product Manual

Line Differential Protection and Control
RED615
Product version: 1.1
The fault recording can be triggered by the
start signal or the trip signal of a protection
block, or by both. The available measurement
modes include DFT, RMS and peak-to-peak.
In addition, the maximum demand current
with time stamp is separately recorded. By
default, the records are stored in a non-vola-
tile memory.
10. Trip-circuit
supervision
The trip-circuit supervision function continu-
ously monitors the availability and operabil-
ity of the trip circuit. It provides open-circuit
monitoring both when the circuit breaker is
in its closed and in its open position. It also
detects loss of circuit-breaker control voltage.

11. Self-supervision

The IED's built-in self-supervision system
continuously monitors the state of the IED
hardware and the operation of the IED soft-
ware. Any fault or malfunction detected will
alert the operator. A permanent IED fault will
block the protection functions of the IED to
prevent incorrect IED operation.
12. Current circuit
supervision
The current circuit supervision function mon-
itors under normal load conditions the bal-
ance of the secondary currents of two current
transformer cores. If the calculated residual
current originating from the line differential
protection core of the current transformer
8
and the measured residual current originat-
ing from the second core in the current
transformer or from a core-balance current
transformer don't match, the line differential
and the negative phase sequence overcurrent
protection functions will be blocked and an
alarm signal will eventually be issued.
13. Protection
communication and
supervision
The communication between the IEDs is
enabled by means of a dedicated fibre-optic
communication channel. The channel is used
for transferring the phase segregated current
value data between the IEDs. The current
phasors from the two IEDs, geographically
located apart from each other, must be time
coordinated so that the current differential
algorithm can be executed correctly. The so
called echo method is used for time synchro-
nization. No external devices such as GPS
clocks are thereby needed for the line differ-
ential protection communication.
The communication channel is further used
for binary signal transfer (BST), transfer-
ring of user configurable binary information,
between the IEDs. There are a total of eight
BST signals available for user definable pur-
poses. The BST signals can originate from the
IED's binary inputs or internal logics, and be
assigned to the remote IED's binary outputs
or internal logics.
The protection communication supervision
continuously monitors the protection commu-
nication link. The IED immediately blocks the
line differential protection function in case
that severe interference in the communication
link, risking the correct operation of the func-
tion, is detected. An alarm signal will eventu-
ally be issued if the interference, indicating
permanent failure in the protection communi-
1MRS756500 A
ABB