Scheme Communication Logic For Residual Overcurrent Protection Ecpsch (85) - ABB RELION 670 SERIES Applications Manual

1MRK 506 369-UUS -
16.6
16.6.1
Line distance protection REL670 2.2 ANSI
Application manual
LoadCurr must be set below the current that will flow on the healthy phase when one or
two of the other phases are faulty and the breaker has opened at remote end (three-phase).
Calculate the setting according to equation 534.
×
0.5 I
Load
min
=
LoadCurr
I
Base
EQUATION1320 V1 EN
where:
ILoadmin is the minimum load current on the line during normal operation conditions.
The timer tLoadOn is used to increase the security of the loss-of-load function for example
to 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 tLoadOn has
elapsed at the same time as the load current in all three phases are above the setting
LoadCurr. In normal acceleration applications there is no need for delaying the release, so
set the tLoadOn to zero.
The drop-out timer tLoadOff is used to determine the window for the current release
conditions 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, 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
Scheme communication
IEC 61850 IEC 60617
identification identification
ECPSCH -
Section 16
(Equation 534)
ANSI/IEEE C37.2
device number
85
769