7 Detailed Functions
7 - 98
High-function General-purpose Inverter 3G3RX-V1 User’s Manual (I578-E1)
• Free-run stop is a method of shutting off the inverter output to stop the motor rotation.
Executing the free-run stop function causes the motor to fall a free-run state, in which it decelerates
due to the load and friction forces exerted on the motor and/or machine and comes to a stop.
• In the Free-run Stop Selection (b088), set how to restart the motor rotating in a free-run state after
the execution of the free-run stop.
• The Free-run Stop Selection (b088) setting is enabled for the following cases.
[When Stop Selection (b091) is set to 01 (Free-run stop)]
Restarting the motor in a free-run stop state when the Stop Selection (b091) is set to 01 (Free-run
stop) causes the motor to restart according to the Free-run Stop Selection (b088) setting.
[When free-run stop (FRS) function is used via a multi-function input terminal]
Setting the Multi-function Input S1 to S8 Selection (C001 to C008) to 11 (FRS) and turning ON the
corresponding input terminal causes the motor to fall in a free-run stop state (with the inverter
output shut off).
Then, when the FRS terminal turns OFF, the motor restarts according to the Free-run Stop
Selection (b088) setting.
However, the motor does not restart when the RUN Command Selection (A002) is set to 02
(Digital Operator).
• Set the Free-run Stop Selection (b088) as follows.
[00: 0-Hz restart]
Forces the inverter to restart at 0 Hz. Note that the inverter restarts suddenly while in a free-run
state. Use this setting if the motor stops shortly due to the load.
[01: Frequency matching restart]
Causes the inverter to restart by recognizing the frequency from the voltage between the motor
terminals during free-run stop and adjusting to it. The inverter restarts at 0 Hz if it cannot fully
recognize the voltage between the motor terminals.
Use this setting if the inverter is in a free-run stop for a few seconds.
[02: Frequency pull-in restart]
Causes the inverter to restart by outputting the starting frequency set in the Starting Frequency
Selection at Frequency Pull-in Restart (b030) to the motor in a free-run stop state and
re-accelerating when the Frequency Pull-in Restart Level (b028) is reached.
This enables a smooth restart independent of the voltage between motor terminals.
Use this setting when the inverter is in free-run state for a long time due to a large load inertia.
• When the Frequency Matching Lower Limit Frequency (b007) is set, executing the frequency pull-in
restart function causes the inverter to restart at 0 Hz if the set frequency or less is detected.
• Immediately after a free-run stop, a large residual voltage remains between motor terminals. If the
inverter restarts the output, an overcurrent may occur. To circumvent this, set the Restart Standby
Time (b003) to a large value (at least 0.3 s).
• While in a free-run stop state, the motor is not subject to external influence because the inverter
output is shut off.
Even if the motor is stopped by an external brake or the effect of other equipment, the inverter can
still be used without detecting any overcurrent.
However, if the motor in a free-run state is rotated externally, the regenerated energy may be fed back
to the inverter. In this case, use the regenerative braking function.
• The examples below assume that you are using the FRS terminal.
Consider that, when the motor is in a free-run stop state, restarting of the inverter occurs in the same
timing as when the FRS terminal turns OFF.
Free-run Stop Selection
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