FUNCTION CODES
Chap 5
■ Zero speed control (d24) (Under vector control with speed sensor only)
To enable zero speed control under vector control with speed sensor, it is necessary to set the speed command
(frequency command) below the starting and stop frequencies. If the starting and stop frequencies are 0.0 Hz,
however, zero speed control is enabled only when the speed command is 0.00 Hz. d24 specifies the operation for
zero speed control at the startup of the inverter.
Data for d24
Zero speed control
at startup
Descriptions
0 Not allowed
When it is smaller than the stop frequency and start frequency the speed
command, zero speed control does not work even ON the operation
command.
Zero speed control to work once you have started once it is set to higher than
the starting frequency the speed command.
1 Allowed
Setting the speed command at below the starting and stop frequencies and
turning a run command ON enables zero speed control.
The table below shows the conditions for zero speed control to be enabled or disabled.
Speed command Run command Data for d24 Operation
At startup
Below the starting and
stop frequencies
OFF ― Stop (Gate OFF)
ON
0 Stop (Gate OFF)
1 Zero speed control
At stop Below the stop frequency
ON ― Zero speed control
OFF ― Stop (Gate OFF)
■ Stop Frequency (Detection mode) (F38) (Under vector control with speed sensor only)
F38 specifies whether to use the actual speed or reference one as a decision criterion to shut down the inverter
output. Usually the inverter uses the detected speed. However, if the inverter undergoes a load exceeding its
capability, e.g., an excessive load, it cannot stop because the motor cannot stop so that the detected speed may
not reach the stop frequency level. If such a situation could arise, select the reference speed that can reach the
stop frequency level even if the detected speed does not, in order to stop the inverter without fail achieving a
fail-safe operation.
• Data setting range: 0 (Detected speed)
1 (Reference speed)
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