Product overview
EL34xx 29Version: 1.5
3.4 Current transformers
In principle, the choice of current transformer for the EL34xx is not critical. The internal resistance within the
current circuit of the EL34xx is so small that it is negligible for the calculation of the total resistances of the
current loop. The transformers should be able to produce a secondary rated current of 1A. The primary
rated current I
pn
can be selected arbitrarily. The common permissible overload of 1.2xI
pn
is no problem for
the EL34xx, but may lead to small measuring inaccuracies.
Accuracy
Please note that the overall accuracy of the set-up consisting of EL34xx and current transformers to a large
degree depends on the accuracy class of the transformers.
No approval as a billing meter
Even an arrangement with a current transformer of class 0.5 or better is not subject to approval and
certification. The EL34xx is not an approved billing meter within the meaning of the standard for
electricity meters (DIN 43 856).
NOTE
DC currents with the EL3453
DC currents can lead to saturation of the internal current transformers and thus to measurement errors!
Current types
The EL34xx can measure any current type up to a limiting proportion of 400Hz. Since such currents are
frequently created by inverters and may contain frequencies of less than 50Hz or even a DC component,
electronic transformers should be used for such applications.
Overcurrent limiting factor FS
The overcurrent limiting factor FS of a current transformer indicates at what multiple of the primary rated
current the current transformer changes to saturation mode, in order to protect the connected measuring
instruments.
NOTE
Attention! Risk of damage to the device!
The EL34xx-xxxx must not be subjected to continuous loads that exceed the current values specified in the
technical data! In systems, in which the overcurrent limiting factors of the transformers allow higher sec-
ondary currents, additional intermediate transformers with a suitable ratio should be used.
NOTE
Attention! Risk of damage to the device!
The EL3453-xxxx must not be permanently loaded with more than I
1
+ I
2
+ I
3
+ I
N
= 20 A total current across
all channels!
Protection against dangerous touch voltages
During appropriate operation of the EL34xx with associated current transformers, no dangerous voltages
occur. The secondary voltage is in the range of a few Volts. However, the following faults may lead to
excessive voltages:
• Open current circuit of one or several transformers
• Neutral conductor cut on the voltage measurement side of the EL34xx
• General insulation fault
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