• When "10 (11, 12, 13)" is set in Pr.162, a restart operation is performed at each start and automatic restart after
instantaneous power failure. When "0 (1, 2)" is set in Pr.162, a restart operation is performed at the first start after a power-
ON, and from the second power-ON onwards, a start from the starting frequency is performed.
Instantaneous (power failure) time
speed N (r/min)
frequency f (Hz)
voltage E (V)
* The output shut off timing differs
according to the load condition
• Because a DC injection brake is applied instantaneously at speed detection during a restart, the speed might drop if the
moment of inertia (J) of the load is small.
• Restart operation with reduced voltage is not available for PM motor control.
Restart coasting time (Pr.57)
• Coasting time is the time from the motor speed detection to the restart operation start.
• To enable restart operation, set "0" (no coasting time) in Pr.57 Restart coasting time. Generally, this setting does not
interfere with inverter operation.
• Inverter operation is sometimes hindered by the size of the moment of inertia (J) of the load or running frequency. Adjust
this coasting time within the range 0.1 s to 30 s to match the load specification.
Adjustment of restart operation (Pr.611)
• Using Pr.611, the acceleration time to reach Pr.20 Acceleration/deceleration reference frequency after a restart
operation can be set. This can be set individually from the normal acceleration time.
• Changing the Pr.21 Acceleration/deceleration time increments setting does not affect the Pr.611 setting increment.
• An IPM motor is a motor with interior permanent magnets. Regression voltage is generated when the motor coasts at an
instantaneous power failure or at a flying start. The inverter's DC bus voltage rises if the motor coasts fast or makes a flying
start in this condition.
When using the automatic restart after instantaneous power failure function (Pr.57 ≠ "9999"), it is recommended to also use
the regenerative avoidance function (Pr.882 Regeneration avoidance operation selection = "1") to make startups stable. If
the overvoltage protective function (E.OV) still occurs with the regeneration avoidance function, also use the retry function
• During PM motor control, the function of the automatic restart after instantaneous power failure works only when an IPM motor
MM-EFS or MM-THE4 is connected.
When a regeneration unit is used, the frequency search may not be available if the rotation speed is about 10% higher than
the rated speed.
at a restart
5.11 (A) Application parameters