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Trip-less Intensification; Auto-restart (restart During Coasting - Toshiba Tosvert VF-AS1 Instruction Manual

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Note 2: If  is set at 2.0kHz or above, it cannot be decreased below 2.0kHz during operation. Changes made to
decrease  below 2.0kHz take effect when operation is restarted after it is stopped.
Note 3: If  is 1.9kHz or less, you cannot change the setting at 2.0kHz or more. Changes made to increase 
to 2.0kHz or above take effect immediately.
Note 4: If  (V/f control mode selection) is set to , , , , or , the inverter sets a lower limit of 2.0kHz for .
Note 5: If you change the carrier frequency, you may need to reduce the inverter's continuous output current.
 Refer to Section 1.4.4, "Current reduction curve."
Note 6: If the motor becomes overloaded when  is set to  or  (carrier frequency not decreased
automatically), an overload trip occurs.
Note 7: For the setting = or  to take effect, power needs to be turned off and then turned back on. And
this parameter is invalidated for the ratings of 90 kW and over.
Note 8: When setting  to  or , be sure to set at 4.0kHz or less.
Note 9: When setting the carrier frequency () between  and .kHz, you are recommended to set 
below 130%.
Note 10: If = or  is set, it automatically becomes V/f control (=0) mode. Moreover, the lower-limit of the
career frequency becomes 4kHz.
Note 11: This parameter works at 200V-55kW and above models, and 400V-90kW and above models.

Trip-less intensification

5.18.1 Auto-restart (Restart during coasting)

• Function
Auto-restart detect the rotating speed and direction of rotation of the motor during coasting or momentary
power failure, to ensure that the motor restarts smoothly (Motor speed search function). This parameter also
allows commercial power operation to be switched to inverter operation without stopping the motor.
During operation, "" is displayed.
1) Auto-restart after momentary power failure (Auto-restart function)
=: This function operates after power has been restored following detection of an undervoltage by the main
Note 1: ST standby signal can be turned on and off by turning on and off the terminal to which it is assigned.
Example: When ST standby signal is assigned to the S3 terminal, setting  to ,  to (cancels the "ST
standby signal always ON" setting. By default, this parameter is set to : always ON.) and  to 
(assigns ST standby signal to the S3 terminal) makes it possible to momentarily stop and restart the motor
by just turning the S3 terminal off and then back on.
* If the motor is restarted in retry mode, this function will operate, regardless of the setting of this parameter.
* The function (=,,,) is activated when the reset of trip or the power is turned on.
* The function (=,) is activated when an undervoltage is detected in the main circuit.
: Auto-restart control selection
• Do not go near motors and equipment.
Motors and equipment that have stopped temporarily after momentary power failure will restart
suddenly after recovery. This could result in unexpected injury.
• Attach warnings about sudden restart after a momentary power failure on inverters, motors and
equipment for prevention of accidents in advance.
Input voltage
Motor speed
circuits and control power.
:At auto-restart after momentary stop
Auto-restart control
: When turning ST operation standby
signal on or off [Note 1]
:  + 
:At start-up
Adjustment range
Default setting
Setting value
 or 


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