Mitsubishi Electric 800 Series Instruction Manual page 353

• The encoder also detects the rotation direction so that the inverter can re-start smoothly even during the reverse rotation.
• Whether or not to detect the rotation direction can be selected by Pr.299 Rotation direction detection selection at
restarting. If the motor capacity is different from the inverter capacity, set Pr.299 = "0" (no rotation direction detection).
• When the rotation direction is detected, the following operation is performed according to Pr.78 Reverse rotation
prevention selection setting.
Pr.299 setting
9999
0 (initial value)
1
○: With rotation direction detection ×: Without rotation direction detection
V/F control, Advanced magnetic flux vector control
Power supply
(R/L1, S/L2,
T/L3)
Motor speed N
(r/min)
Inverter output
frequency f(Hz)
Inverter output
voltage E(V)
Speed
Coasting
detection
+
time (Pr.57)
time
* The output shut off timing differs
according to the load condition.
NOTE
• The rotation speed detection time (frequency search) changes according to the rotation speed of the motor (maximum 1
second).
• When the inverter capacity is two ranks or greater than the motor capacity, the overcurrent protective function (E.OC[]) is
sometimes activated and prevents the inverter from restarting.
• If two or more motors are connected to one inverter, this function operates abnormally. (The inverter does not restart
successfully.)
• 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.
• If reverse operation is detected when "1" (reverse rotation disabled) is set to Pr.78, operation decelerates by reverse rotation
and then changes to forward rotation when the start command is forward rotation. The inverter does not restart when the start
command is reverse rotation.
352
14. (A) Application Parameters
14.7 Automatic restart after instantaneous power failure / flying start with an induction motor
Pr.78 setting
0 1
○ × ×
× × ×
○ ○ ○
Instantaneous (power failure) time
*
Restart cushion
time (Pr.58 setting)
Acceleration time
at a restart
(Pr.611 setting)
2
Real sensorless vector control
Power supply
(R/L1, S/L2,
T/L3)
Motor speed N
(r/min)
Inverter output
frequency f(Hz)
output voltage
E(V)
Coasting
+
time (Pr.57)
* The output shut off timing differs
according to the load condition.
Instantaneous (power failure) time
*
Speed
Acceleration time
detection
time
at a restart
(Pr.611 setting)