ABB RED650, Техническое руководство, Страница: 112 / 926

1. Output OPENCT provides instant information to indicate that an open CT
circuit has been detected.
2. Output OPENCTAL provides a time-delayed alarm that the open CT circuit
has been detected. Time delay is defined by the parameter tOCTAlarmDelay .
3. Integer output OPENCTIN provides information on the local HMI regarding
which open CT circuit has been detected (1=CT input No 1; 2=CT input No
2).
4. Integer output OPENCTPH provides information on the local HMI regarding
in which phase an open CT circuit has been detected (1=Phase L1; 2= Phase
L2; 3= Phase L3).
Once the open CT condition is declared, the algorithm stops to search for further
open CT circuits. It waits until the first open CT circuit has been corrected. Note
that once the open CT condition has been detected, it can be reset automatically
within the differential function. It is not possible to externally reset an open CT
condition. To reset the open CT circuit alarm automatically, the following
conditions must be fulfilled:
• Bias current is for at least one minute smaller than 120%
• The open CT condition in the defective CT circuit has been corrected (for
example, current asymmetry disappears)
• The above two conditions are fulfilled for a longer time than defined by the
setting parameter
tOCTResetDelay
If an open CT has been detected in a separate group of three CTs, the algorithm is
reset either when the missing current returns to the normal value, or when all three
currents become zero. After the reset, the open CT detection algorithm starts again
to search for open CT circuits within the protected zone.
6.1.7.5 Binary signal transfer
SEMOD52489-4 v4
There is space for eight binary signals integrated in the telegram of the line
differential analog communication.
6.1.7.6 Line differential protection logic LDLPSCH
GUID-687F26CE-20EF-424A-A355-6308CED80E6C v7
Line differential protection logic (LDLPSCH) is a support function to the Line
differential protection functions. The function gathers and coordinates local IED
signals and the signals from remote IEDs between the Line differential protection
functions and the LDCM communication module.
The function acts as the interface to and from Line differential protection.
The task of LDLPSCH is to transfer the signals via LDCM between IEDs in the
protection zone. Once LDLPSCH receives a block or trip signal from one IED, this
block or trip signal is transferred to other IEDs by LDLPSCH function.
Section 6
1MRK 505 394-UEN A
Differential protection
106 Line differential protection RED650 2.2 IEC
Technical manual