(9)
DIR 1000587R0002 (Version 02)
2.4.5. Neutral
Protection
LSIG allows the current signal of the neutral pole to be processed with different ratios in relation to the phase values. The follow-
ing values can be set for this protection: I
n
N =Off - 50% - 100% - 200% * I
n
.
The neutral protection is set by default at a current
value equal to 50% of the phase regulation.
Regulation of the neutral value (I
n
N) must conform to the following formula: (I
1
x I
n
N)
Iu.
With four-pole circuit-breakers, the trip unit performs the test automatically and transmits a fault signal following failure to con-
form to this formula. If the circuit-breaker is the three-pole type with external neutral, no tests will be performed by the trip unit
and user needs to correct the settings.
E.g.
With CB 140G-R 2000 (Iu=2000A), Rating plug 1000A (In=1000A) and I
1
=1In, the I
n
N setting can be: 50-100-200%.
With CB 140G-R 2000 (Iu=2000A), Rating plug 2000A (In=2000A) and I
1
=1In, the I
n
N can be: 50-100%.
The I
1
=1In setting is the maximum setting of the protection against overload. The real permissible maximum setting must take
account of derating due to the temperature, terminals used and the altitude.
ATTENTION: In some installations, where particularly high harmonics occur, the current circulating on the neutral
may be higher than that of the phases.
ATTENTION: For three-pole circuit-breakers without external neutral, the Neutral protection setting must be Off,
otherwise the sensor presence error will be signalled (Error CS).
In these cases, connect T5-T6 to the sliding contacts, as shown in the wiring diagrams.
ATTENTION: Failure to comply with the setting limits of “I
1
” and “I
n
N” may result in damage to the circuit-
breaker and consequent risks even for the operator.
ATTENTION: The protection setting is automatically 100% when the current value exceeds 15.5xIn on the neutral.
2.4.6.
Protection against instantaneous short-circuit “Iinst”
Iinst is a software override protection. The purpose of this protection is to maintain the integrity of the circuit-breaker and instal-
lation in the case of particularly high current requiring shorter reaction times than those guaranteed by the instantaneous short-
circuit protection.
The protection cannot be disabled. It has a single fi xed time protection curve and a fi xed threshold level.
2.4.7.
Summary table of protections
Pr
otection
Disabling
Trip threshold
Trip time
Trip threshold
tolerance
(2)
Trip time
tolerance
(2)
L
(t=k/I
2
)
I1
=
0.4 - 0.425 - 0.45 - 0.475 - 0.5 -
0.525 - 0.55 - 0.575 - 0.6 - 0.625 -
0.65 - 0.675 - 0.7 - 0.725 - 0.75 -
0.775 - 0.8 - 0.825 - 0.85 - 0.875 -
0.9 - 0.925 - 0.975 - 1 x In
t1 = 3 - 12 - 24 - 36 - 48 -
72 - 108 - 144 s
(1)
@I
f
=3I1
Release between
1.05 and 1.2 x I1
± 10% I
f
6 x In
± 20% I
f
> 6 x In
S
(t=k)
I2
=
1 - 1.5 - 2 - 2.5 - 3 - 3.5 - 4 - 5 -
6 - 7 - 8 - 8.5 - 9 - 9.5 - 10 x In
Where I
f
> I2
± 7% I
f
6 x In
± 10% I
f
>6 x In
The best of the two data:
± 10% or ± 40 ms
t2 = 0.1 - 0.2 - 0.3 - 0.4 -
0.5 - 0.6 - 0.7 - 0.8 s
S
(t=k/I
2
)
I2
=
1 - 1.5 - 2 - 2.5 - 3 - 3.5 - 4 - 5 -
6 - 7 - 8 - 8.5 - 9 - 9.5 - 10 x In
t2 = 0.1 - 0.2 - 0.3 - 0.4 -
0.5 - 0.6 - 0.7 - 0.8 s
@ 10 In
± 7% I
f
6 x In
± 10% I
f
>6 x In
± 15% I
f
6 x In
± 20% I
f
> 6 x In
I
(t=k)
I3
=
1.5 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 -
10 - 11 - 12 - 13 - 14 - 15 x In
30 ms
± 10%
G
(t=k)
I4
=
0.2 - 0.3 - 0.4 - 0.6 - 0.8 - 0.9 - 1
x In
Where I
f
> I4
± 7%
The best of the two data:
± 10% or ± 40 ms
t4 = 0.1 - 0.2 - 0.4 - 0.8 s
G
(t=k/I
2
)
I4
=
0.2 - 0.3 - 0.4 - 0.6 - 0.8 - 0.9 - 1
x In
Minimum trip time
± 7%
± 15%
t4 = 0.1 - 0.2 - 0.4 - 0.8 s
(1) The minimum value of this trip is 1s regardless of the type of curve
set (self-protection).
(2) These tolerances apply in the following conditions:
- Self-energized trip unit in service conditions
(no start-up) with 2 or 3 supplied phases
and/or in presence of auxiliary supply.
- operating temperature within the -25°...70° range.
- primary current values within the operating limits (see par. 2.2.7)
For all cases not covered by the above table, the following tolerances apply:
Protection Trip threshold
Trip time
L
Release between 1.05 e 1.25 x I1
± 20%
S
± 10%
± 20%
I
± 15%
60ms
G
± 10%
± 20%
Others
± 20%
