Application Guide - NP900 Series
429 (504
)
A996A
3.6.5.1
M
EASURED INPUT VALUES
Function block uses analog current measurement values. Function block always utilizes
peak-to-peak measurement from samples and by user selection the monitored magnitude
can be either fundamental frequency RMS values, True RMS values from the whole
harmonic specter of 32 components or peak to peak values. -20ms averaged value of the
selected magnitude is used for pre-fault data registering.
Table 3.6.5.1-251 Analogic magnitudes used by the CLPU function.
Signal
Description
Time base
IL1RMS
Fundamental RMS measurement of phase L1/A current
5 ms
IL2RMS
Fundamental RMS measurement of phase L2/B current
5 ms
IL3RMS
Fundamental RMS measurement of phase L3/C current
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.
3.6.5.2
P
ICK
-
UP CHARACTERISTICS
Pick-up and activation of the CLPU function is controlled by
ILow, IHigh and IOver
setting
parameters, which defines the maximum and minimum allowed measured current before
action from the function. The function constantly calculates the ratio in between of the
setting values and measured magnitude (Im) per all three phases. Reset ratio of 97 % is
inbuilt in the function and is always related to the setting
value. The setting value is
common for all measured phases and single-, dual- or all phases Im exceed of the Iset
value will cause pick-up operation of the function.
Table 3.6.5.2-252 Pick-up characteristics setting
Name
Range
Step
Default
Description
ILow
0.10 … 40.00 x In
0.01 x In
0.20 x In
Pick-up setting for low current detection. All
measured currents must be below this
setting in order the CLPU signal shall be
activated.
IHigh
0.10 … 40.00 x In
0.01 x In
1.20 x In
Pick-up setting for high current detection.
Any measured current must exceed this
setting directly from the ILow condition in
order CLPU signal shall be activated.
IOver
0.10 … 40.00 x In
0.01 x In
2.00 x In
Pick-up setting for over current detection. In
case this setting is exceeded by any
measured current the CLPU signal shall be
released immediately.
