156
FUNCTION CHARACTERISTICS
— Breaker failure - BF (H, L, T)
When the protection issues a trip command but, due to an anomaly, the circuit breaker cannot open,
the breaker failure protection BF 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 protection) or, trip
of external protections acquired by means binary input, if enabled with trip ProExt;
B) The CB is closed (the CB state may be acquired by means two binary inputs connected to the
auxiliary contacts 52a and 52b) or the fundamental component of at least one phase current I
L1
,
I
L2
, I
L3
is greater than the I
BF
> adjustable threshold or the fundamental component of the residual
current I
EC
is greater than the I
EBF
> adjustable threshold.
The three controls are separately activated and programmable. If the control of the circuit-breaker
status is provided, the reference circuit-breaker suitable for the application must be programmed.
If both conditions are held along the set operate time t
BF
, 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
BFEnable parameter available inside
the Set \ Profile A (or B or C or D)\ Breaker failure-BF menu.
BF start from Circuit breaker
By means CB Input parameter it is possible enable the control of CB status if BF Start is active.
CB status control is enable by setting CB in CB Input parameter and if two binary inputs are config-
ured in order to acquire the status of CB auxiliary contacts (52a and 52b).
CB status enabling is available in Set \ Profile A (or B or C or D) \ Breaker failure-BF menu, while
CB acquisition function assignment to the logic inputs (52a and 52b is settable in Set\Inputs ING1(X)\
Binary input IN1-1...(INX-y) menus.
To enable the BF protection to operate with trips coming from external protections, one binary input
must be designed to acquire the relative contacts.; for this purpose it is necessary select TripPro-
tExt function in Set\Inputs ING1(X)\ Binary input IN1-1...(INX-y) menus.
All parameters I
BF
>, I
EBF
> and t
BF
are settable separately for profile A, B, C, D calibration sets by Set
\ Profile A (or B or C or D) \ Breaker failure-BF menus.
Logical block (Block1)
If BF-BLK1 parameter [BFlogical block] is set to ON, and a binary input is designed for logical block
(Block1), BFprotection is blocked for the binary input activation time. Trip timer is held in reset con-
dition, so the operate time counting starts when the input block goes down.
[1]
Logical block enabling parameter is available in Set \ Profile A (or B or C or D) \ Breaker failure-BF
menu, while the Block1function must be assigned to the selected binary input in et\Inputs ING1(X)\
Binary input IN1-1...(INX-y) menus.
Note 1 The exhaustive treatment of the logic block (Block 1) function may be found in the “Logic Block” paragraph inside CONTROL AND MONITORING
section
XMR-T EQUIPMENT MANUAL
Ed. 2.9 - 02/2021
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