Siemens SENTRON VL Series System Manual page 50

3WL air circuit breakers
3.3 Metering functions
Accuracy
The load of the metering function PLUS is 27 kΩ so that up to six metering functions can be
connected simultaneously to a voltage transformer with apparent power of 2.5 VA (note
accuracy class and cable length!).
The accuracy of the voltage transformer depends on the number of connected metering
functions per voltage transformer:
● Class 0.5 for 1 to 3 metering functions
● Class 3 for 4 to 6 metering functions
These specifications apply for ambient temperatures of 30 to 50 °C and a primary-side
voltage of 80 to 120% for a period of one year.
If the accuracy specified in the tables below has to be achieved, a Class 0.5 voltage
transformer must be used. As well as the measured values specified in the table, the
metering function also provides a minimum and maximum measured value.
Note
If the metering function is retrofitted at the customer end, the specified accuracy values
cannot be guaranteed due to lack of calibration with the trip unit.
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3WL/3VL circuit breakers with communication capability - PROFIBUS
System Manual, 03/2011, A5E01051353-02