Arcteq AQ-T215, Instruction Manual

Page: 183 / 411

Figure. 5.3.12 - 133. Simplified function block diagram of the U0> function.
Measured input
The function block uses analog voltage measurement values. The function block uses RMS values. A
-20 ms averaged value of the selected magnitude is used for pre-fault data registering.
Table. 5.3.12 - 116. Measurement inputs of the U0> function.
Signal Description Time base
U0RMS RMS measurement of voltage U0/V 5ms
U
L1
RMS RMS measurement of voltage U
L1
/V 5ms
U
L2
RMS RMS measurement of voltage U
L2
/V
5ms
U
L3
RMS RMS measurement of voltage U
L3
/V 5ms
The selection of the AI channel currently in use is made with a setting parameter. In all possible input
channel variations the pre-fault condition is presented with a 20 ms averaged history value from -20 ms
from a START or TRIP event.
Pick-up
The
U
set
setting parameter controls the pick-up of the U0> function. This defines the maximum allowed
measured voltage before action from the function. The function constantly calculates the ratio
between the
U
set
and the measured magnitude (
U
m
) for neutral voltage. The reset ratio of 97 % is built
into the function and is always relative to the U
set
value. The setting value is common for all measured
amplitudes, and when the U
m
exceeds the U
set
value it triggers the pick-up operation of the function.
Table. 5.3.12 - 117. Pick-up settings.
Name Description Range Step Default
Pick-up setting U0set> Pick-up setting 1.00…99.00%U
n
0.01%U
n
20.00%U
n
The pick-up activation of the function is not directly equal to the START signal generation of the
function. The START signal is allowed if the blocking condition is not active.
A AQ Q-T215 -T215
Instruction manual
Version: 2.04
182