Application Guide - NP900 Series
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A996A
Activation and deactivation of each individual stage can be done inside the protection
function menus info-tab.
Outputs of the function are Start Trip and Blocked signals. Setting parameters are static
inputs for the function which are changed only by user input in the setup phase of the
function. Frequency protection utilizes total of eight separate setting groups which can be
selected from one common source.
The function can operate on instant or time delayed mode.
The operational logic consists of input magnitude processing, threshold comparator, two
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 frequency 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 figure is presented the simplified function block diagram of the FRQV
function.
