Mitsubishi Electric FR-A820-00046 Instruction Manual page 847

Parameters
Braking operation selection at the time of Real sensorless vector control (Pr. 850 = "0, 1")
The braking operation at the time of the Real sensorless vector control can be selected between the
DC injection brake (initial value) or the Zero speed control.
By setting Pr. 850 "Brake operation selection" = "1", zero speed control will be performed under the
frequency set in Pr. 10 "DC injection brake operation frequency".
NOTES Under Real sensorless vector control, when the X13 signal turns ON while Pr. 11 = "8888", the zero
speed control is activated regardless of the Pr. 850 setting.
When restarting from brake operation at the time of Real sensorless vector control, set Pr. 850 =
"1" (zero speed control). In case of setting value "0" (DC injection brake), it may take approximately
2 s from the time the start up command is input until it actually is output.
Magnetic flux decay output shutoff and magnetic flux decay output shutoff signal
(X74 signal, Pr. 850 = "2")
● The failure of inverter or increased error in motor may occur due to effect of the motor residual
magnetic flux at the time when the inverter output is shut off when frequent start and stop
(inching operation) is repeated at the time of Real sensorless vector control. If this is the case, set
Pr. 850 = "2" (magnetic flux decay output shutoff ) or turn ON the magnetic flux decay output
shutoff (X74) signal to decay the magnetic flux at a stop, and then shut off the output.
● With Pr. 850 = "2", deceleration starts at turning OFF of the start command, and the magnetic flux
decay output shutoff is activated when the estimated speed becomes lower than Pr. 10 "DC
injection brake operation frequency".
● With the brake sequence function is set enabled, the magnetic flux decay output shutoff is
activated when the frequency becomes lower than 0.5 Hz or the Pr. 13 "Starting frequency" setting,
whichever smaller, during deceleration.
● Inverter output voltage shutoff timing when Pr. 850 = "2"
Normal operation
Start command
Speed command
Pr. 10 "DC injection
brake operation
Magnetic flux decaying
Output voltage
Mechanical brake
MC on the output side
Fig. 5-330:
Maximum time for the magnetic flux decay operation
● Regardless of the Pr. 850 setting, the magnetic flux decay output shutoff will operate immediately
when the Magnetic flux decay output shutoff signal (X74) is turned ON. For the X74 signal, set "74"
in any of Pr. 178 to Pr. 189 (input terminal function selection) to assign the function.
FR-A800
(STF, STR)
(rotation per
second)
frequency"
ON
ON
ON
RUN
RY2 ON
ON
ON
Do not turn OFF MC
during this period
Inverter output voltage shutoff timing during normal operation and during brake sequence
Start command
(STF, STR)
Speed command
(rotation per
minute)
Pr. 13 "Starting
frequency" or 0.5 Hz
(whichever is lower)
Magnetic flux decaying
Magnetic flux decay
processing time
Output voltage
RUN
RY2
Mechanical brake
MC on the output side
(G) Control parameters
During brake sequence
ON
Magnetic flux decay
processing time
ON
ON
ON
ON
ON
Do not turn OFF MC
during this period
I002170E, I002171E
5 - 667