Ice NP900 Series, Инструкция по применению

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Application Guide - NP900 Series 172 (504
)
A996A
In the following figure is presented the simplified function block diagram of the positive
sequence protection.
Figure 3.2.16.2-88 Simplified function block diagram of the sequence voltage function.
3.2.16.3 M
EASURED INPUT VALUES
The function block uses analog voltage measurement values. Function block utilizes
always fundamental frequency RMS values. -20 ms averaged value of the selected
magnitude is used for the pre-fault data registering.
Table 3.2.16.3-117 Analogic magnitudes used by the VUB function.
Signal Description Time base
U
1
RMS Fundamental RMS measurement of voltage U
1
/V 5 ms
U
2
RMS Fundamental RMS measurement of voltage U
2
/V 5 ms
U
3
RMS Fundamental RMS measurement of voltage U
3
/V 5 ms
In fundamental frequency RMS value the pre-fault condition is presented with 20 ms
averaged history value from -20 ms of Start or Trip event.
3.2.16.4 P
ICK
-
UP CHARACTERISTICS
Pick-up of the VUB function is controlled by
Uset
setting parameter, which defines the
maximum or minimum allowed calculated U1 or U2 voltage before action from the
function. The function constantly calculates the ratio in between of the Uset and calculated
U1 or U2 magnitude (Uc). The monitored voltage is chosen with the parameter in the
INFO-page with the parameter
Measured magnitude
.