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Function assignment of external
terminal and control
4
PARAMETERS
(3) Speed detection hysteresis (Pr.870)
⋅This function prevents chattering of the speed detection sig-
nals.
When an output frequency fluctuates, the up to frequency
signal (SU) and output frequency detection signals (FU and
FU2) may repeat ON/OFF (chatters).Setting hysteresis to
the detected frequency prevents chattering of these signals.
REMARKS
The output frequency compared with the set frequency changes depending on the control method.
CAUTION
⋅ Changing the terminal assignment using Pr. 190 to Pr. 196 (output terminal function selection) may affect the other functions.
Set parameters after confirming the function of each terminal.
♦ Parameters referred to ♦
Pr. 190 to Pr. 196 (output terminal function selection) Refer to page 140
Pr.870
Pr.42
Output
frequency
(Hz)
ON
ON
ON
FU
OFF OFF
Example of output frequency detection signal (FU)
REMARKS
Setting a higher value to this parameter slows the response of
frequency detection signals (SU, FU, and FU2).
Control Method Compared Output Frequency
V/F control Output frequency
Simple magnetic flux vector control Output frequency before slip compensation
IPM motor control Estimated frequency (actual motor rotation per minute)