Thytronic NA11 User Manual

69
NA11 - Manual - 02 - 2009
FUNCTION CHARACTERISTICS
Breaker failure - BF
Preface
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
I
L1
, I
L2
, I
L3
is greater than the I
BF>
adjustable threshold or the fundamental component of the
residual current I
E
is greater than the I
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 t
BF
, 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 ON the BF Enable parameter available inside
the Set \ Profi le A(or B) \ Breaker failure-BF menu.
All the I
BF>
, I
EBF
and t
BF
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 ON, and two binary inputs are
designed for acquire the 52a and 52b auxiliary contacts
[1]
, 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 \ Inputs \ Binary input IN1(2...) menus (IN1 or IN...
matching).
Logical block (Block1)
If the BF-BLK1 parameter (BF logical block) is set to ON, 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.
[2]
The enabling parameter are 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 \
Inputs \ Binary input IN1(x) menus (IN1 or INx matching).
Note 1 Both auxiliary contact state 52a and 52b must be acquired (two binary inputs are required).
Note 2 The exhaustive treatment of the logic block (Block 1) function may be found in the “Logic Block” paragraph inside CONTROL AND MONITORING
section
A)
B)
all-FBF.ai
Schema a blocchi generale della funzione di mancata apertura interruttore (BF)
Block1
BLK1 BF
I
L1
...I
L3
I
E
52b
52a
Trip ProtExt
Start BF
Trip BF
Block1
&
BF-BLK1
BF Enable I
BF
> I
EBF
> t
BF
all-FBF.ai
Schema a blocchi generale della funzione di mancata apertura interruttore (BF)
Block1
BLK1 BF
I
L1
...I
L3
I
E
52b
52a
Trip ProtExt
Start BF
Trip BF
Block1
&
BF-BLK1
BF Enable I
BF
> I
EBF
> t
BF

Thytronic NA11 Specifications

General

Brand	Thytronic
Model	NA11
Category	Relays
Language	English