FUNCTION CHARACTERISTICS
126
NA30 - Manual - 04 - 2022
Circuit breaker supervision
Preface
Several diagnostic metering and monitoring function are available:
• By means 52a and 52b auxiliary contacts, the CB position is acquired. Depending on such information
the Open and/or Close commands can be safely issued by user.
• An adjustable threshold can be set for a wear estimate of the breaker contacts; the current values
(
S
I or
S
I
2
) are summed and compared to a user-adjustable threshold. When the threshold or the
number of operations is exceeded the relay can activate an output relay. The function helps to
adjust maintenance planning.
• By means 52a and 52b auxiliary contacts, the opening time is calculated and compared to a user-ad-
justable threshold. If the threshold is exceeded the relay can activate an output relay.
Operation and settings
According to the conventional contact position
• 52a is the auxiliary contact that is in the same position as the circuit breaker, (52a open = CB
open),
• 52b is the auxiliary contact that is in the opposite position as the circuit breaker, (52a open = CB
closed).
To acquire the CB position, the
52a
and
52b
function must be set inside the
Set \ Inputs \ Binary
input 1
and
Set \ Inputs \ Binary input x
menus
.
The
IN1 tON
,
IN2 tON
,
IN1 tOFF
and
IN2 tOFF
time delays must be reset to zero and the
Logic
parameter must be set to
Active-ON
inside the
Set
\ Inputs \ Binary input IN1
and
Set \ Inputs \ Binary input INx
menus.
CIRCUIT BREAKER COMMANDS
Two output relays can be set to command CB opening and closing; the
CBopen-K
and
CBclose-K
function must be set inside the
Set \ Circuit breaker supervision \ LEDs-relays allocation
menu; the
CB position can be visualized by means two LEDs (
CBopen-L
and
CBclosed-L
parameters).
All the parameters are common for
Profile A
and
Profile B
.
CIRCUIT BREAKER DIAGNOSTIC
Four different criteria can be select.
1) Number of CB trip mode (
ModeN.Open ON
). When the number of operations (
N.Open
) is ex-
ceeded, an output relay and/or LED can be activated.
2) Cumulative CB currents mode (
ModeSumI ON
). When the per-phase value exceeds the thresh-
old, an output relay and/or LED can be activated.
3) Cumulative CB I
2
t mode (
ModeSumI^2t ON
). The tripping energy I
2
t is calculated on the base of
current measure at the time of the open command on the base of the circuit breaker opening time
provided for I
2
t calculation (
tbreak
). When the per-phase value exceeds the threshold, an output
relay and/or LED can be activated.
4) CB operating time mode (
Mode-tOpen ON
). The time interval between the trip command and the
CB open acquisition is calculated on the base of a programmable relay (
Ktrig-break
). When the
time interval (
tbreak>
) is exceeded, an output relay and/or LED can be activated.
The four criteria can be contemporaneously or separately set.
All the named parameters are available inside the
Set \ Circuit Breaker supervision \ CB Diagnostic
menu.
Fun-CB-position.ai
Logic diagram concerning the circuit breaker diagnostic function
Towards CB diagnostic
TR
IP
PIN
G
M
AT
RIX
(LE
D)
52a ON/OFF
t
mask
0
T
t
mask
CB monitoring
Opening transition
52b ON/OFF
52a
52
52b
+
U
AUX
-
U
AUX
IN-
IN+
52a
IN-
IN+
52b
Binary input INx (x=1,...5)
T
0
INx
t
ON
T
0
n.o.
n.c.
INx tON
Logic
INx tOF F
INx
t
OFF
Binary input INx (x=1,...5)
T
0
INx
t
ON
T
0
n.o.
n.c.
INx tON
Logic
INx tOF F
INx
t
OFF
=1
