Scheme Communication Logic For Residual Overcurrent Protection Ecpsch (85) - ABB REC670 Applications Manual

1MRK 511 401-UUS A
15.4
15.4.1
15.4.2
Bay control REC670 2.2 ANSI
Application manual
The setting of the minimum current detector, MinCurr, should be set higher than the
unsymmetrical current that might flow on the non faulty line, when the breaker at
remote end has opened (three-phase). At the same time it should be set below the
minimum load current transfer during normal operations that the line can be subjected
to. By default, MinCurr is set to 5% of IBase.
The pick-up timer tLowCurr determine the window needed for pick-up of the
minimum current value used to release the function. The timer is by default set to 200
ms, which is judged to be enough to avoid unwanted release of the function (avoid
unwanted trip).
Scheme communication logic for residual overcurrent
protection ECPSCH (85)
Identification
Function description
Scheme communication logic for
residual overcurrent protection
Application
To achieve fast fault clearance of ground 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.
One communication channel is used in each direction, which can transmit an on/off
signal if required. The performance and security of this function is directly related to
the transmission channel speed and security against false or lost signals.
In the directional scheme, information of the fault current direction must be transmitted
to the other line end.
With directional comparison in permissive schemes, a short operate time of the
protection including a channel transmission time, can be achieved. This short operate
time enables rapid autoreclosing function after the fault clearance.
During a single-phase reclosing cycle, the autoreclosing device must block the
directional comparison ground-fault communication scheme.
Scheme communication
IEC 61850 IEC 60617
identification identification
ECPSCH -
Section 15
IP14711-1 v2
M14882-1 v2
ANSI/IEEE C37.2
device number
85
M13919-3 v6
479