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328
FUNCTION CHARACTERISTICS
—
Breaker failure - BF
Preface
The protection is available in Side H [BF(H)] and in Side L [BF(L)] and in order to dodge any misunder-
standing Breaker Failure features are described separately.
Breaker failure Side H [BF(H)]
When the protection issues a trip command but, due to an anomaly, the circuit breaker cannot open,
the breaker failure protection BF(H) issues a back-up trip command to trip adjacent circuit breakers.
The breaker failure function may be started by internal protective function (if associated with BF) or
by external protections.
Operation and settings
The starting of the timer occurs if both the following conditions are filled:
A) Start and trip of internal protective elements (trip of elements matched with BF(H) protection) or,
trip of external protections acquired by means binary input, if enabled with trip ProExt Side H;
B) The CB is closed (the CB state may be acquired by means two binary inputs connected to the au-
xiliary contacts 52a and 52b) or the fundamental component of at least one phase current on side
H
I
L1H
,
I
L2H
,
I
L3H
is greater than the
I
BF(H)>
adjustable threshold or the fundamental component of
the residual current
I
ECH
is greater than the
I
EBF(H)>
adjustable threshold.
The three controls are separately activated and programmable. If the control of the circuit-breaker
status is provided, the reference circuit-breaker (CB Side H or CB Side L) suitable for the application
must be programmed.
If both conditions are held along the set operate time
t
BF(H)
, the BF element trips at deadline, vice
versa the timer is cleared and the function is restored.
In order to restore the BF element as quickly as possible, with start of the same protection (see A
condition), additionally to the trip of some internal protections, their starts are required (start reset
is faster than trip reset).
The element may be enabled or disabled by setting
ON
the
BF(H)Enable
parameter available insi-
de the
Set \ Profile A (or B)\ Breaker failure-BF(H)
menu.
XMR-D EQUIPMENT MANUAL
Ed. 2.9 - 02/2021