ABB REL670 2.2 IEC, Applications Manual

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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).
16.6 Scheme communication logic for residual
overcurrent protection ECPSCH
IP14711-1 v2
16.6.1 Identification
M14882-1 v2
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Scheme communication logic for
residual overcurrent protection
ECPSCH - 85
16.6.2 Application
M13919-3 v6
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.
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 earth-fault communication scheme.
The communication logic module 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 the Current reversal and weak-
end infeed logic for residual overcurrent protection (ECRWPSCH) function.
Metallic communication paths adversely affected by fault generated noise may not
be suitable for conventional permissive schemes that rely on signal transmitted
during a protected line fault. With power line carrier, for example, the
communication signal may be attenuated by the fault, especially when the fault is
close to the line end, thereby disabling the communication channel.
Section 16
1MRK 506 369-UEN B
Scheme communication
722 Line distance protection REL670 2.2 IEC
Application manual