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.
Table. 5.6.1. - 205. Residual current input signals selection
Name Range Step Default
Description
I0
Input
0: Not
in use
1: I01
2: I02
-
Not in
use
Selection of residual current measurement input. In cases if the residual current is
measured with separate CT the residual current circuit can be monitored also with the
CTS function. This does not apply summing connection (Holmgren etc.) in case of
phase current CT summed to I01 or I02 input use selection 0:Not in use.
Pick-up characteristics
Current dependent pick-up and activation of the CTS function is controlled by ISet and I0set setting
parameters, which de nes the 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 and selected residual current input. Reset ratio of 97 % is inbuilt in the function
and is always related to the settingvalue. 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. 5.6.1. - 206. Pick-up characteristics setting
Name
Range
Step
Default
Description
Iset
Highlimit
0.01 …
40.00xIn 0.01xIn 1.20xIn
Pick-up threshold for phase current measurement. This setting limit de nes the
upper limit for the phase current pick-up element. If this condition is met it is
considered as fault and the CTS is not activated
Iset
Lowlimit
0.01 …
40.00xIn
0.01xIn 0.10xIn
Pick-up threshold for phase current measurement. This setting limit de nes the
lower limit for the phase current pick-up element. If this condition is met it is
considered as one trigger for the CTS activation.
Iset Ratio
0.01 …
100.00% 0.01%
10.00%
Pick-up ratio threshold for phase current min and max values. This condition has
to be met in order CTS is activated.
I2/I1 ratio
0.01 …
100.00% 0.01%
49.00%
Pick-up ratio threshold for Negative sequence / Positive sequence currents
calculated from the phase currents. This condition has to be met in order CTS is
activated. In full single phasing fault when one of the phases is completely lost
the ratio shall be 50%. Setting of 49% allows 0.01 xIn to flow in one phase when
the two other are 1.00 xIn
Isum
difference
0.01 …
40.00xIn
0.01xIn 0.10xIn
Pick-up ratio threshold for calculated residual phase current to measured
residual current. If the measurement circuit is healthy the sum of these should be
0.
The pick-up activation of the function is not directly equal to start-signal generation of the function.
Start signal is allowed if blocking condition is not active. From binary signals the activation of the pick-
up is immediate when the monitored signal is activated.
Function blocking
In the blocking element the block signal is checked in the beginning of each program cycle. Blocking
signal is received from the blocking matrix for the function dedicated input. If the blocking signal is not
activated when the pick-up element activates, a START signal is generated and the function proceeds
to the time characteristics calculation.
If blocking signal is active when pick-up element activates a BLOCKED signal will be generated and the
function shall not process the situation further. If START function has been activated before blocking
signal it will reset and the release time characteristics are processed as in case of when pick-up signal
is reset.
AQ-T257
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
258