Ice NP900 Series, Инструкция по применению

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Application Guide - NP900 Series 471 (504
)
A996A
3.7.2 F
USE FAILURE
(VTS) (60)
Voltage transformer supervision is used to detect errors in the secondary circuit of the
voltage transformer. This signal is mostly used as alarming function or to disable functions
that require adequate voltage measurement.
3.7.2.1 M
EASURED INPUT VALUES
The function block uses analog voltage measurement values. Function uses the
fundamental frequency magnitude of the voltage measurement inputs and calculated
positive-, negative- and zero sequence currents.
Table 3.7.2.1-276 Analogic magnitudes used by the VTS function.
Signal Description Time base
U
L12
RMS Fundamental RMS measurement of voltage U
L12
/V 5 ms
U
L23
RMS Fundamental RMS measurement of voltage U
L23
/V 5 ms
U
L31
RMS Fundamental RMS measurement of voltage U
L31
/V 5 ms
U
L1
RMS Fundamental RMS measurement of voltage U
L1
/V 5 ms
U
L2
RMS Fundamental RMS measurement of voltage U
L2
/V 5 ms
U
L3
RMS Fundamental RMS measurement of voltage U
L3
/V 5 ms
U1P Positive sequence voltage 5 ms
U2N Negative sequence voltage 5 ms
UZ0 Zero sequence voltage 5 ms
U
L12
Ang Fundamental angle of U
L12
voltage 5 ms
U
L23
Ang Fundamental angle of U
L23
voltage 5 ms
U
L31
Ang Fundamental angle of U
L31
voltage 5 ms
U
L1
Ang Fundamental angle of U
L1
voltage 5 ms
U
L2
Ang Fundamental angle of U
L2
voltage 5 ms
U
L3
Ang Fundamental angle of U
L3
voltage 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.
3.7.2.2 P
ICK
-
UP CHARACTERISTICS
Voltage dependent pick-up and activation of the VTS function is controlled by Voltage low
pick-up and Voltage high detect
setting parameters. If at least one measured voltage of
the three are under the set low value, VTS pick-up will activate. Also if at least two of the
three voltages are over high detect value VTS pick-up will activate. The function
constantly calculates the ratio in between of the setting values and measured magnitude
per all three phases and selected residual current input.