Mitsubishi Electric FATEC FR-A800 Manual page 105

7
REVIEW OF INSTALLATION ENVIRONMENT
(b) Operation of automatic restart after instantaneous power failure
1) When an instantaneous power failure occurs during operation, the motor starts coasting.
2) After a power restoration, applying the DC voltage from the inverter to the coasting motor
carries the DC to the motor. (Refer to Fig. 7.9
This DC includes the ripple cycle proportional to the motor speed.
3) Input the signal from the current detector to the CPU and count the ripple cycle to
determine the motor speed.
4) The inverter outputs with the frequency according to the motor speed. (Refer to Fig. 7.9
B
to reduce the starting current of the motor.
Power supply voltage
Output frequency
Motor speed
Motor current
Fig. 7.9 Example of automatic restart after instantaneous power failure operation
When the automatic restart after instantaneous power failure function is supported (Example: FR-
A800 series)
When using the automatic restart after instantaneous power failure function, short across terminals
CS and SD.
Fig. 7.10 Wiring for automatic restart after instantaneous power failure operation
7.1 Power supply of inverter (harmonics and instantaneous power failure)
100
.) After that, restart the inverter operation while increasing the output voltage gradually
220 VAC
0
60 Hz
0
1800 r/min
50 A
0
Instantaneous
power failure
time
440 ms
MCCB
RA
.)
Ａ
B
Motor coasting
DC voltage
A
application
Reduced
voltage
Reset time
time
600 ms 300 ms
Rotation speed detection time
140 ms
Inverter
CS
STF
SD SD
60 Hz
1800 r/min
Acceleration
time
520 ms
M