The operational logic consists of input magnitude processing, input magnitude selection, threshold
comparator, block signal check, time delay characteristics and output processing.
Inputs for the function are the operating mode selections, setting parameters and measured and pre-
processed voltage magnitudes and binary input signals. Function outputs START, TRIP 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 three output signal. In instant operating
mode the function outputs START and TRIP events simultaneously with equivalent time stamp. Time
stamp resolution is 1ms. Function provides also cumulative counters for START, TRIP and BLOCKED
events.
In the following gure is presented the simpli ed function block diagram of the NOV function.
Figure. 5.4.11. - 58. Simpli ed function block diagram of the NOV function.
Measured input values
Function block uses the analog voltage measurement values. Function block utilizes fundamental
frequency RMS values. -20ms averaged value of the selected magnitude is used for pre-fault data
registering.
Table. 5.4.11. - 112. Analogic magnitude used by the NOV function.
Signal
Description
Time base
U0RMS
Fundamental RMS measurement of voltage U0/V
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.
Real-time info displayed by the function
The relays Info-page displays useful information in real time of the state of the protection function either
through relays HMI display or with AQtivate software when connection there is a connection to relay
and Live Edit-mode is activated.
Name
Unit
Description
U0> Pick-up
setting
V
Primary voltage required for tripping. The displayed pick-up voltage level depends on the chosen
U0 measurement input selection, pick-up setting and the voltage transformer settings.
Expected
operating time s
Displays the expected operating time in case a fault occurs
AQ-T257
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
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