Beckhoff SCT Series, Документация

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Product overview
SCT5xxx 10 Version: 1.0
Fig. 3: Principle coil current transformer
WARNING
Dangerous voltages with secondary side not connected
The secondary winding must be connected to a current measuring device or short-circuited, otherwise high
core losses or dangerous voltages may occur on the secondary side. Before replacing the measuring elec-
tronics in the secondary circuit, the current transformer must therefore be short-circuited at its secondary
terminals.
Grounding of secondary terminals
According to DIN VDE 0141 (01/2000) paragraph 5.3.4, current and voltage transformers for nomi-
nal voltages from U
m
= 3.6 kV must be grounded on the secondary side. For low voltages
(U
m
≤ 1.2 kV), grounding is not required if the transformer housings do not have any metal surfaces
with large contact areas.
Characteristic values and calculation
In principle, the construction, and thus also the calculation, correspond to a normal transformer. The basic
relationship between input and output current is determined by the ratio of the number of turns N of the
primary and secondary sides. An important characteristic value in the design of a current transformer is
therefore the transformer ratio.
I
Out
= N
1
/N
2
* I
In