Ice NP900 Series, Инструкция по применению

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Application Guide - NP900 Series 308 (504
)
A996A
The TRF function outputs are dependent of the set transformer data in that sense that per
unitized measured currents are related to transformer nominal values. In following
diagram are presented the TRF function outputs in different kind of situations.
Figure 3.5.1-150 TRF function outputs activation.
“No load” signal is activated when the current is under “No load current” limit (0.2 xIn)” for
more than 10 ms time. If the current increases from this situation to “Heavy overloading
limit (> 1.3 x In) then “HV/LV inrush detection” signals are activated. If measured current is
in between of low detection and nominal current the “Load normal” signal is activated. If
measured current is in between of nominal and heavy overloading current “Overloading”
signal is activated.
These signals can be used for informational and also for transformer related logics and
monitoring usage. For example constant long duration heavy overloading may cause the
transformer oil ageing and thus the maintenance should be applied before scheduled in
order to prevent possible problems in the transformer.
1.1.1.1 S
ETTINGS AND SIGNALS
Settings of the transformer status monitor (TRF) function are mostly shared with
transformer protection functions in the transformer module of the IED. In following table
are shown the functions which use these settings also.