ABB Relion 670 Series Applications Manual page 398

Section 14
Scheme communication
The timer
avoid unwanted release due to transient inrush current when energizing the line power
transformer. The loss-of-load function will be released after the timer
same time as the load current in all three phases are above the setting
acceleration applications there is no need for delaying the release, so set the
The drop-out timer
for Loss-of-load. The timer is by default set to 300ms, which is judged to be enough to secure the
current release.
The setting of the minimum current detector,
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,
IBase .
The pick-up timer
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).
14.4 Scheme communication logic for residual overcurrent
protection ECPSCH (85)
14.4.1 Identification
Function description
Scheme communication logic for
residual overcurrent protection
14.4.2 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.
392
tLoadOn is used to increase the security of the loss-of-load function for example to
tLoadOff is used to determine the window for the current release conditions
tLowCurr determine the window needed for pick-up of the minimum current
MinCurr , should be set higher than the
IEC 61850 IEC 60617
identification identification
ECPSCH -
1MRK 511 358-UUS A
tLoadOn has elapsed at the
LoadCurr . In normal
tLoadOn to zero.
MinCurr is set to 5% of
ANSI/IEEE C37.2
device number
85
Application manual
IP14711-1 v2
M14882-1 v2
M13919-3 v5