Scheme Communication Logic For Residual Overcurrent Protection Ecpsch (85) - ABB RELION RET670 Applications Manual

Section 16
Scheme communication
16.5
16.5.1
16.5.2
832
Set tPickUpWEI to 10 ms, a short delay is recommended to avoid that spurious carrier
received signals will activate WEI and cause unwanted communications.
Set the voltage criterion UPP< and UPE< for the weak-end trip to 70% of the system
base voltage UBase. The setting should be below the minimum operate voltage of the
system but above the voltage that occurs for fault on the protected line. The phase-to-
phase elements must be verified to not operate for phase to earth faults.
When single phase tripping is required a detailed study of the voltages
at phase-to-phase respectively phase-to-earth faults, at different fault
locations, is normally required.
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.
IEC 61850 IEC 60617
identification identification
ECPSCH -
Transformer protection RET670 2.2 ANSI
1MRK 504 163-UUS A
IP14711-1 v2
M14882-1 v2
ANSI/IEEE C37.2
device number
85
M13919-3 v6
Application manual