Current Transformer - Beckhoff EL3773 Documentation

es muss eine ARRAY-Variable vorliegen die über ADS erreichbar ist. Dies kann eine PLC-Variable oder eine
im System Manager definierte ARRAY-Variable sein. Diese wird dann vom Scope2 erkannt.
Summary: an array variable have to be provided which is reachable via ADS. This can be a PLC variable of
a POU or a defined array variable by the system manager or alternatively the ADS server of the terminals
device is just activated.
6.9

Current transformer

In principle, the choice of current transformer for the EL3773 is not critical. The internal resistance within the
current circuit of the EL3773 is so small that it is negligible for the calculation of the total resistances of the
current loop. The transformer must be able to supply a secondary rated current of 1 or 1.5 A; the primary
rated current I can be chosen as desired. Overloading of the EL3773 is permissible up to 1.2 x I
pn
Technical Data [} 15] for max. permissible overvoltage/overcurrent.
Accuracy
Please note that the overall accuracy of the set-up consisting of EL3773 and current transformers to a large
degree depends on the accuracy class of the transformers.
No approval as a billing meter
A set-up with a class 0.5 current transformer cannot be approved or authenticated. The
EL3773 is not an approved billing meter according to the electricity meter standard (DIN 43
Note
856).
Current types
The EL3773 can measure any type of current.
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
devices.
Attention! Risk of damage to the device!
The max. permissible input values according to the Technical Data [} 15] must be observed!
Additional intermediate transformers must be used in systems in which the overcurrent lim-
Attention
iting factors of the transformer allow higher secondary currents!
Protection against dangerous touch voltages
During appropriate operation of the EL3773 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 path of one or more transformers
• Neutral conductor cut on the voltage measurement side of the EL3773
• General insulation fault
WARNING Risk of electric shock!
The complete wiring of the EL3773 must be protected against accidental contact and
equipped with associated warnings! The insulation should be designed for the maximum
WARNING
conductor voltage of the system to be measured!
The EL3773 allows a maximum voltage of 500 V for normal operating conditions. The conductor voltage on
the current side must not exceed 500 V! For higher voltages, an intermediate transformer stage should be
used!
EL3773 Version: 2.5
Commissioning
/U ; see
pn pn
123