Break in Primary System
To record breaks in the primary system, set standardization on I
2
/I
1
(Reference value = pos. seq. current) to
achieve a higher sensitivity (independence of load current). For a 1-phase break, the ratio of the negative-
sequence current and the positive-sequence current can be described according to the following equation
with the negative-system and zero-sequence impedance (Z
2
, Z
0
).
[fo_function46BreakinPrimarySystem, 1, en_US]
In the isolated system or with 1-sided ground, the zero-sequence impedance is infinity and thus the ratio is
always 1. Observe a 2-sided grounded network and set the zero-system impedance equal to the negative-
system impedance, then the ratio is 0.5. If a wire break occurs in the secondary circuit, a value of 1 or 0.5 is
also possible.
For a 2-phase break, current can only flow with a 2-sided grounded network. In this case, the ratio I
2
/I
1
= 1. If a
partial 1-phase load is expected, the ratio is also set. The setting value is dependent on the maximum 1-phase
load. For a setting value of 10 %, the phase current can be 30 %.
If you want to prevent an indication with short circuits, activate the current limiting to, for example, 1.2
I
rated,obj
(Current limitation I
max
= yes; Maximum phase current = 1.2 A at 1 A transformer and ideal adaptation
to the protected object). Here calculate the current with the current transformer ratio to the secondary circuit.
The setting of the protection stage is aligned to the network type. A setting value of 25 % Threshold = 25
% offers a sufficiently high sensitivity. If errors occur in the current transformer circuit, there can, however,
also be a tripping. To prevent overfunctions during the AREC cycles, the time delay for the tripping must be set
long. A time of 60 s Operate delay = 60.00 s offers sufficient reliability.
Settings Menu
Functions > Function Config
Parameter Range Settings
Default Gn1 Gn2 Gn3 Gn4
46 Negative Sequence Over-
current
Enabled
Disabled
Disabled
Functions > Protection > 46 > 46DT-n
Parameter Range Settings
Default Gn1 Gn2 Gn3 Gn4
Element Enabled
Disabled
Disabled
Setting 0.05 to 4 I
rated
, Δ 0.01 I
rated
0.1 ⋅
I
rated
Delay 0 to 14400 s 0.02 s
Functions > Protection > 46 > 46IT-n
Parameter Range Settings
Default Gn1 Gn2 Gn3 Gn4
Element Enabled
Disabled
Disabled
Setting 0.05 to 2.5 I
rated
, Δ 0.01 I
rated
0.25 ⋅
I
rated
5.7.5
Protection and Automation Functions
5.7 46 Negative-Sequence Overcurrent Protection
186 Reyrolle 7SR5, Overcurrent Protection Device, Device Manual
C53000-G7040-C014-1, Edition 11.2019
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