The operational logic consists of input magnitude processing, threshold comparator, block signal
check, time delay characteristics and output processing.
Inputs for the function are setting parameters and measured and pre-processed current magnitudes
and binary input signals. Function outputs CLPU act and BLOCKED signals which can be used for
direct IO controlling and also for user logic programming. The function registers its operation into 12
last time-stamped registers and also generates general time stamped ON/OFF events to the common
event buffer from each of the two output signal. Time stamp resolution is 1ms. Function provides also
cumulative counters for CLPU act and BLOCKED events.
In the gure below simpli ed function block diagram of the CLPU function is presented.
Figure. 5.5.5. - 141. Simpli ed function block diagram of the CLPU function.
Measured 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. 5.5.5. - 198. 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.
Pick-up characteristics
Pick-up and activation of the CLPU function is controlled by ILow, IHigh and IOver setting parameters,
which de nes 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
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.
AQ-F255
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
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