Connections
In distribution networks, 1 current transformer is required per phase A, B, C. A total of 3 transformers are
needed. The following diagram is a generic representation of a specfic CT wiring diagram where the
connecting terminals are showed.
[dw_specificCT_wiringdiagram, 1, en_US]
Terminals
•
P1 - Primary Input
•
P2 - Primary Output
•
S2 - Output for current measurement
•
S1 - Input for current measurement
•
D and C - Test winding terminals
CT Selection
Selection of the CT depends on the on the rated current of the transformer (I
rated
), rated voltage of the trans-
former (V
rated
) and the rated power of the transformer (P
rated
).
[fo_RATEDCurrent, 1, --_--]
Therefore,
[fo_RATEDCurrent_example, 1, --_--]
For the above example, from the specific CT table (Table 5-1) the following CT type is selected:
CT Type
I
s
Range CT Ratio I
smin
Recommended I
s
CT01 8 A to 28 A 7.2/0.075 8 A 17 A - 18 A
As CT01 is selected, 7SR46 Argus can measure a short-circuit current up to 20 times of the highest CT rated
current. This means for CT selected above, 7SR46 Argus can measure current up to 28 A x 20 = 560 A
NOTE
During CT selection, relay continuous current and short time withstand rating shall be considered.
Test Winding
In case of 7SR46 Argus relay, the necessary current to perform the testing is provided through the non
conventional current transformers. These CTs have a pass-through hole (from P1 to P2) for primary current
Applications
5.2 Specific CTs
72 Reyrolle, 7SR46 Device, Manual
C53000-G7040-C103-1, Edition 10.2022
To Next Page
Loading...
