CARLO GAVAZZI WM4-96 - PROGRAMMING Manual page 56

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The variables measured by the instrument are correct
if the inputs have been connected according to the
right polarities (see figure below). Should the connec-
ction not be conforming to the right polarities, meas-
uring and retransmission errors may occur, both due to the
wrong direction of the current flowing in the primary/secondary
of the ammeter transformer being connected.
Application example of the digital filter
It's necessary to stabilize the value of the displayed V
variable, that varies between 222V and 228V, maintaining a
4-dgt indication. The parameters of the digital filter must be set
as follows:
• DISPLAY: 4 digits
• RANGE: the variable may have variations within the average
amplitude value equal to ±1.3% of the rated value of this vari-
able which is obtained as follows: [(228-222) / 2 = ±3V, then
±3*100/231V= ±1.3% where 231V is the rated phase-neutral
value of an input at 400V)].
The "range" parameter, that is the action range of the digital fil-
ter, will be set at a value which is slightly higher than the per-
centage amplitude of the fluctuation: for example 1.5%.
• COEFFICIENT: if the new value acquired by the instrument is
within the action range of the filter, the new displayed value is cal-
culated by summing (algebraically) to the previous value the vari-
ation divided by the filtering coefficient. As a consequence, a
GSM
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Useful Info
List of Variables
59
L-N
58