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Frequency arrival output [FA1] uses the
standard output frequency (parameter
F001) as the threshold for switching. In
the figure to the right, Frequency
Arrival [FA1] turns ON when the
output frequency gets within 0.5 Hz
below or 1.5 Hz above the target
constant frequency. This provides
hysteresis that prevents output chatter
near the threshold value. The hysteresis
effect causes the output to turn ON
slightly
early
as the speed approaches
the threshold. Then the turn-OFF point
is slightly
delayed
. The timing is further
modified by a small 60 ms delay. Note
the active low nature of the signal, due
to the open collector output.
Frequency arrival output [FA2] works
the same way; it just uses two separate
thresholds as shown in the figure to the
right. These provide for separate
acceleration and deceleration thresholds
to provide more flexibility than for
[FA1]. [FA2] uses C042 during
acceleration for the ON threshold, and
C0043 during deceleration for the OFF
threshold. This signal also is active low
and has a 60 ms delay after the
frequency thresholds are crossed.
Having different accel and decel
thresholds provides an asymmetrical
output function. However, you can use
equal ON and OFF thresholds, if
desired.
FA1
signal
Output
freq.
0.5 Hz
F001
F001
60ms
1.5 Hz
0.5 Hz
ON
60ms
1.5 Hz
ON
0
FA2
signal
Output
freq.
thresholds
C042 accel.
60ms
ON
60ms
0
C043 decel.
0.5 Hz
1.5 Hz
4
−
39
Operations and
Monitoring