Scheme Communication Logic For Residual Overcurrent Protection Ecpsch - ABB REC670 Applications Manual

1MRK 511 401-UEN A
15.4
15.4.1
15.4.2
Bay control REC670 2.2 IEC
Application manual
×
0.5 I
Load
min
=
LoadCurr
I
Base
EQUATION1320 V1 EN-US
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
Identification
Function description
Scheme communication logic for
residual overcurrent protection
Application
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
Scheme communication
IEC 61850 IEC 60617
identification identification
ECPSCH -
Section 15
(Equation 127)
IP14711-1 v2
M14882-1 v2
ANSI/IEEE C37.2
device number
85
M13919-3 v6
445