Mitsubishi Electric FR-A800 Series Instruction Manual page 638

• When "10 to 13, or 1010 to 1013" is set in Pr.162, a restart operation is performed at each start and automatic restart after
instantaneous power failure. When "0 to 2, or 1000 to 1002" 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.
Power supply
(R/L1,S/L2,T/L3)
Motor
speed N (r/min)
Inverter output
frequency f (Hz)
Inverter output
voltage E (V)
Coasting
time (Pr.57)
* The output shut off timing differs
according to the load condition
NOTE
• 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 sensorless vector 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 the output frequency. Adjust
this coasting time within the range 0.1 to 30 seconds 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.
NOTE
• 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
(Pr.67).
• During PM sensorless vector control, the automatic restart after instantaneous power failure function operates only when an
IPM MM-CF motor is connected.
When a built-in brake or a regeneration unit is used, the frequency search may not be available at 2200 r/min or higher. The
restart operation cannot be performed until the motor speed drops to a frequency where the frequency search is available.
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Instantaneous (power failure) time
*
Speed
detection
+
time
Acceleration time
at a restart
(Pr.611 setting)
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5. PARAMETERS
5.14 (A) Application parameters
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