Ice NP900 Series, Инструкция по применению

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Application Guide - NP900 Series 297 (504
)
A996A
function. Overexcitation function utilizes total of eight separate setting groups which can
be selected from one common source.
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.
3.4.5.1 M
EASURED INPUT VALUES
Analog system voltages and system frequency measurement values are used for the
function block.
Table 3.4.5.1-197 Analog magnitudes used by the V/Hz function.
Signal Description Time base
U12 RMS U12 System voltage RMS 5 ms
U23 RMS U23 System voltage RMS 5 ms
U31 RMS U31 System voltage RMS 5 ms
f Measured system frequency f 5 ms
3.4.5.2 P
ICK
-
UP CHARACTERISTICS
Pick-up of the V/Hz function is controlled by Pick-up V/Hz > nominal setting parameter,
which defines the maximum measured voltage allowed in relation to the measured
frequency before action from the function. The function constantly calculates the ratio in
between of the Pick-up V/Hz nominal and calculated Umeas/fmeas. Reset ratio of 97% of
the pick-up setting is inbuilt in the function and is always related to the Pick-up V/Hz
nominal value.