Restart coasting time (Pr. 57)
● The coasting time is the time up till detection of the motor speed and start of restart control.
● 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
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.
A PM 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 volt-
age 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 (Pr. 67).
During PM motor control, the automatic restart after instantaneous power failure function oper-
ates only when an MM-EFS/MM-THE4 IPM motor 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 rating.
● An IPM motor is a motor with interior permanent magnets. High voltage is generated at
motor terminals while the motor is running.
Do not touch motor terminals and other parts until the motor stops to prevent an electric
● When the automatic restart after instantaneous power failure function is selected, the motor
suddenly starts (after reset time passes) when an instantaneous power failure occurs.
Stay away from the motor and machinery.
Apply the supplied CAUTION stickers to easily visible places when automatic restart after
instantaneous power failure has been selected.
Parameters referred to
Pr. 65, Pr. 67 to Pr. 69
Pr. 178 to Pr. 189
Reverse rotation prevention selection
(input terminal function selection)
Regeneration avoidance operation selection
(A) Application parameters
page 5-115, page 5-117
5 - 425