Wiring
3.3 Current transformer selection data
Analog input module AI Energy Meter 480VAC ST (6ES7134-6PA20-0BD0)
24 Manual, 12/2015, A5E36061895-AA
Checking the ratio of burden load and power loss
The rated burden of the transformer must be 1.5 to 2 times greater than the power loss in the
connection circuit to ensure that the transformer is not overloaded and that the current
limitation is ensured during a short-circuit.
At a maximum secondary current of 4 A the power loss in the connection circuit is calculated
in accordance with the following formula for a connection cable (outgoing and incoming line)
with a length of 10 m and a cross-section of 1.0 mm
2
and a burden resistance of the Energy
Meter of 25 mΩ:
The ratio of the rated burden and the power loss in the connection circuit thus amounts to:
The required ratio of rated burden and power loss in the connection circuit lies within the
required range. The transformer is dimensioned sufficiently large.
Technical specifications (Page 92)
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