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NVA100X-D - Manual - 02 - 2016

FUNCTION CHARACTERISTICS

Breaker failure - BF

Preface

The protection is available in all versions.

When the protection issues a trip command but, because an anomaly, the circuit breaker cannot
open, the breaker failure protection 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 ﬁ lled:

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;

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 on
side L

L1L

L2L

L3L

is greater than the

BF>

adjustable threshold or the fundamental component of

the residual current

is greater than the

EBF>

adjustable threshold.

The breaker failure protection reliability is improved by means of the CB position control or phase

or residuaI current measure; the trip can arise also for wrong auxiliary contacts state (if the current
is greater than the adjustable threshold ) or for trip of external protections (frequency, voltage,..)

without current (with CB closed information supplied from state of auxiliary contacts).
If the information concerning the CB position is not achievable (for instance the auxiliary contacts

are unavailable), such control must be disabled.

If both conditions are held along the set operate time

, the BF element trips at deadline, vice versa

the timer is cleared and the function is restored.

To the purpose 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

the

BF Enable

parameter available inside

the

Set \ Proﬁ le A(or B) \ Breaker failure-BF

menu.

All the

BF>

EBF

and

parameters can be set separately for

Proﬁ le A

and

Proﬁ le B

; they are avail-

able inside the

Set \ Proﬁ le A(or B) \ Breaker failure-BF

menu.

BF start from Circuit breaker

If the

CB Input

parameter (BF Start from circuit breaker) is set to

, and two binary inputs are

designed for acquire the 52a and 52b auxiliary contacts, the control of the CB position is enabled. If

the information concerning the CB position is not available, such control must be disabled by setting

OFF

the

CB Input

parameter. The parameter is available inside the

Set \ Proﬁ le A(or B) \ Breaker

failure-BF

menu, the

52a

and

52b

function must be assigned to the selected binary inputs inside

Set \ Inputs \ Binary input IN1(x)

menus (IN1 or INx matching).

To enable the breaker failure protection to operate with trips coming from external protections, one

binary input must be designed to acquire the relative contacts. The

TripProtExt

function must be

assigned to the selected binary input inside the

Set \ Board 1(2) inputs \ Binary input IN1-1...(IN2-x)

menus.

Logical block (Block1)

If the

BF-BLK1

parameter (BF logical block) is set to

, and a binary input is designed for logical

block (Block1), the breaker failure protection is blocked off whenever the given input is active. The
trip timer is held in reset condition, so the operate time counting starts when the input block goes
down.

[1]

The enabling parameter is available inside the

Set \ Proﬁ le A(or B) \ Breaker failure-BF

menu, while the

Block1

function must be assigned to the selected binary input inside the

Set \

Board 1(2) inputs \ Binary input IN1-1...(IN2-x)

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