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16
LIMITERS
Limiters act by limiting or changing the output of variables, keeping them at levels that do not harm
the system.
U/f LIMITER
The
U/f
limiter is used to reduce the excitation voltage during motor shutdown. When reducing the
rotation, the generator requires more excitation to maintain the voltage and to avoid this actuates
the limit
U/f
. The
U/f
block is shown in figure 9.
A saída do bloco
U/f
envia o erro para o controle PI.
➢
Frequency of operation of U/f: 54 Hz for 60 Hz, 45 Hz for 50 Hz, according to configuration
of frequency selection jumpers.
➢
Fall U/f: Set reference voltage / reference frequency.
➢
Signaling: Alarm Led constantly lit in
Purple
.
Figure 9 - U/f block
Figure 10 - U/f Adjustment
Figure 11
–
Frequency selection jumper
