Application Guide - NP900 Series
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)
A996A
Time stamp resolution is 1ms. Function provides also cumulative counters for START,
TRIP and BLOCKED events.
In the following figure is presented the simplified function block diagram of the NOV
function.
Figure 3.2.17-92 Simplified function block diagram of the NOV function.
3.2.17.1
M
EASURED INPUT VALUES
Function block uses the analog voltage measurement values. Function block utilizes
fundamental frequency RMS values. -20ms averaged value of the selected magnitude is
used for pre-fault data registering.
Table 3.2.17.1-121 Analogic magnitude used by the NOV function.
Signal
Description
Time base
U0RMS
Fundamental RMS measurement of voltage U0/V
5 ms
Selection of the used AI channel is made with a setting parameter. In all possible input
channel variations pre-fault condition is presented with 20 ms averaged history value from
-20 ms of Start or Trip event.
