Phase Discontinuity Protection; Circuit-Breaker Failure Protection - ABB REF 610 Technical Reference Manual

REF 610
4.1.4.5.
4.1.4.6.
26
Feeder Protection Relay
Technical Reference Manual - ANSI Version

Phase discontinuity protection

Phase discontinuity protection
The phase discontinuity protection detects phase unbalance between phases Ia, Ib The phase discontinuity protection detects phase unbalance between phases Ia, Ib
and Ic, caused by a broken conductor, for instance. The difference between the and Ic, caused by a broken conductor, for instance. The difference between the
minimum and maximum phase currents is calculated as follows: minimum and maximum phase currents is calculated as follows:
=
I ( unbal )
When the current difference exceeds the set pickup value of the phase discontinuity When the current difference exceeds the set pickup value of the phase discontinuity
element, 46, the element will generate a pickup signal after a ~ 100 ms. When the element, 46, the element will generate a pickup signal after a ~ 100 ms. When the
set operate time at definite-time characteristic elapses, the element will generate a set operate time at definite-time characteristic elapses, the element will generate a
trip signal. The element will be reset in 70 ms after the current difference has fallen trip signal. The element will be reset in 70 ms after the current difference has fallen
below the set pickup value of the element. below the set pickup value of the element.
The phase discontinuity protection will be disabled when all phase currents fall The phase discontinuity protection will be disabled when all phase currents fall
below 0.1 x CT. below 0.1 x CT.
It is possible to block the tripping of the phase discontinuity element by applying a It is possible to block the tripping of the phase discontinuity element by applying a
digital input signal to the relay. digital input signal to the relay.
Element 46 can be set out of operation in SGF3. This state will be indicated by Element 46 can be set out of operation in SGF3. This state will be indicated by
dashes on the LCD and by "999" when the set pickup value is read via serial dashes on the LCD and by "999" when the set pickup value is read via serial
communication. communication.

Circuit-breaker failure protection

The circuit-breaker failure protection (CBFAIL) detects situations where the trip
remains active although the circuit breaker should have operated.
If a trip signal generated via output PO1 is still active and the current has not been
cut off on expiration of the CBFAIL set operate time, the CBFAIL will generate a
trip signal via output PO2.
Note!
The CBFAIL will not be triggered in case of a thermal alarm, thermal or external
trip.
The CBFAIL can also be selected to be triggered by applying a digital input signal
to the relay. In this case, the CBFAIL will generate a trip signal via output PO2 if
the current has not been cut off on expiration of the set operate time.
Internal triggering is selected by activating the CBFAIL in SGF and external
triggering by activating the CBFAIL in SGB. Both triggering options can be selected
at the same time.
Normally, the CBFAIL controls the upstream circuit breaker. However, it can also
be used for tripping via redundant trip circuits of the same circuit breaker.
−
I I
max min
I
max
1MRS 755535
x 100 %