56
•The output frequency does not need to be adjusted, except in the following cases.
a. If the wiring distance between the inverter and motor is long, lower the carrier
frequency as shown below to allow less leakage current.
Wiring distance <30m 30m~50m 50m~100m >100m
Carrier frequency (Cn-34) <15kHz <10kHz <5KHz <2.5KHz
b. If there is great irregularity in speed or torque, lower the carrier frequency.
(29) Speed Search Detection Level (Cn-35)
(30) Speed Search Time (Cn-36)
(31) Min. Baseblock Time (Cn-37)
(32) Speed Search V/F Curve (Cn-38)
•The speed search function will search the speed of a frequency coasting motor
from the frequency command or max. frequency downward. And it will restart up
smoothly from that frequency or max. frequency. It is effective in situations such
as switching from a commercial power supply to an inverter without tripping
occurred.
•The timing of speed search function as shown below：
FWD(or REV) run command
Speed search command
Max output frequency
(or running frequency
while the speed search
is being performed)
Output frequency
Min baseblock time
voltage at speech search
ouput voltage
speed search operation
retuen to voltage at
normal operation
Synchronous speed dectection
<0.5 sec
Fig. 27 Speed search timing chart
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