Siemens SENTRON VL Series System Manual page 46

3WL air circuit breakers
3.3 Metering functions
If increased harmonics are measured, it is advisable to carry out a 3-phase system analysis.
This measurement, including the neutral conductor, must be carried out with the appropriate
harmonics measuring devices over an extended period up to the 100th harmonic. The right
choice of measuring connection point and professional analysis of the measured data are
essential components in developing a concept that removes or at least reduces the
harmonics and associated faults.
Standards
You can find further information in the EN 6100-2-4 standard where upper limits are defined
for harmonics. The application area of this standard refers to harmonics up to the
50th harmonic order, intermediate harmonics up to the 50th harmonic order and voltage
components at higher frequencies above the 50th harmonic order.
Waveform buffer
The metering function PLUS has two independent waveform buffers (A and B) with which the
current measured values are captured and buffered for one second. The buffer is
continuously overwritten with the new measured values. If an event (trigger event) now
occurs, the 1 s measured values are saved for later analysis of the events.
Typically, the function is used for analyzing a short-circuit (trigger event). But other events
can also be analyzed.
Each of these waveform buffers has 8 channels, one each for the currents I
I as well as for the voltages V
g
of 1.649 kHz, and the values are buffered for 1 s.
The waveform can be represented and exported with Switch ES Power, for example.
46
, V and V . Each channel is sampled with a frequency
L1N L2N L3N
3WL/3VL circuit breakers with communication capability - PROFIBUS
, I , I
L1 L2
System Manual, 03/2011, A5E01051353-02
, IN and
L3