ABB REL650 series, Applications Manual

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12.4.3 Setting guidelines
The parameters for the local acceleration logic functions are set via the local HMI or
PCM600.
GlobalBaseSel : Selects the global base value group used by the function to define ( IBase ),
( VBase ) and ( SBase ).
Set ZoneExtension to Enabled when the first trip from selected overreaching zone shall be
instantaneous and the definitive trip after autoreclosure a normal time-delayed trip.
Set LossOfLoad to Enabled when the acceleration shall be controlled by loss-of-load in
healthy phase(s).
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
176 .
min
0.5
Load
Base
I
LoadCurr
I
×
=
EQUATION1320 V1 EN
(Equation 176)
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 .
Section 12
1MRK 506 334-UUS A
Scheme communication
406
Application manual