Scheme Communication Logic For Residual Overcurrent Protection Ecpsch (85) - ABB REL650 Applications Manual

1MRK 506 334-UUS A
12.5
12.5.1
12.5.2
Application manual
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.
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, 85) 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.
Scheme communication
IEC 61850 IEC 60617
identification identification
ECPSCH -
Section 12
ANSI/IEEE C37.2
device number
85
407