Mitsubishi Electric FR-A800, Instruction Manual

Page: 418 / 1042

(F) Setting of acceleration/deceleration time and acceleration/deceleration pattern Parameters
5 - 238
Setting the acceleration/deceleration time in the low-speed range (Pr. 791, Pr. 792)
If torque is required in the low-speed range (less than 10% of the rated motor frequency) under PM
sensorless vector control, set the Pr. 791 "Acceleration time in low-speed range" and Pr. 792 "Decel-
eration time in low-speed range" settings higher than the Pr. 7 "Acceleration time" and Pr. 8 "Decel-
eration time" settings so that the mild acceleration/deceleration is performed in the low-speed range.
Such a setting is especially effective when the low-speed range high-torque characteristic is disabled
(Pr. 788="0"). (When RT signal or X9 signal is turned ON, the second or third acceleration/deceleration
time setting is prioritized.)
NOTES The reference frequency during acceleration/deceleration depends on the Pr. 29 "Acceleration/
deceleration pattern selection" setting. (Refer to page 5-240.)
The RT and X9 signals can be assigned to an input terminal by setting Pr. 178 to Pr. 189 (input ter-
minal function selection). Changing the terminal assignment may affect other functions. Set
parameters after confirming the function of each terminal.
The RT (X9) signal acts as the second (third) function selection signal and makes the other second
(third) functions valid. (Refer to page 5-428.)
RT signal is assigned to the terminal RT in the initial status. Set "3" in any of Pr. 178 to Pr. 189 (input
terminal function selection) to assign the RT signal to another terminal.
I002555E
Fig. 5-87: Setting the acceleration/deceleration time in the low-speed range
NOTES Set Pr. 791 higher than Pr. 7, and Pr. 792 higher than Pr. 8. If set as Pr. 791 < Pr. 7, the operation is
performed as Pr. 791 = Pr. 7. If set as Pr. 792 < Pr. 8, the operation is performed as Pr. 792 = Pr. 8.
Refer to page 8-8 for the rated motor frequency of MM-CF.
Acceleration time
in low-speed range
Slope set by Pr. 791
Acceleration time
Slope set by Pr. 7 Deceleration time
Slope set by Pr. 8
Low-speed range
(rated motor frequency/10)
Time
Deceleration time
in low-speed range
Slope set by Pr. 792
Output fr
equenc
y (H
z)