Mitsubishi Electric FR-D720-0.2K-G Instruction Manual page 101

Setting of acceleration/deceleration time and acceleration/ deceleration pattern
(2) Deceleration time setting (Pr. 8, Pr. 20)
Use Pr. 8 Deceleration time to set the deceleration time required to reach 0r/min from Pr. 20 Acceleration/deceleration reference
speed.
Set the deceleration time according to the following formula.
Deceleration
=
time setting
Example) How to find the setting value for Pr. 8 when decreasing the rotation
speed from the maximum speed of 1800r/min in 10s with Pr. 20 =
3000r/min (initial setting).
(3) Set two kinds of acceleration/deceleration times (RT signal, Pr. 44, Pr. 45 )
Pr. 44 and Pr. 45 are valid when the RT signal is ON.
When "9999" is set to Pr. 45, the deceleration time becomes equal to the acceleration time (Pr. 44).
For the RT signal, set "3" in any of Pr. 178 to Pr. 182 (input terminal function selection) to assign the function.
NOTE
 When the acceleration/deceleration pattern is S-pattern acceleration/deceleration A (refer to page 100), the acceleration/
deceleration time is the time required to reach the rated motor speed.
 Changing terminal assignment may affect the other functions. Set parameters after confirming the function of each
terminal.
(4) Setting the acceleration/deceleration time in the low-speed range (Pr. 791, Pr. 792)
If torque is required in a low-speed range (lower than 10% of the rated speed), set Pr. 791 Acceleration time in low-speed
range and Pr. 792 Deceleration time in low-speed range settings higher than the Pr. 7 Acceleration time and Pr. 8 Deceleration
time settings so that the mild acceleration/deceleration is performed in the low-speed range.
The setting value of Pr. 785 PM control torque boost is the maximum generatable torque in the low-speed range.
page 86.
)
For the acceleration time, set the time takes to accelerate from a stop to Pr. 20 Acceleration/deceleration reference speed. For
the deceleration time, set the time takes to decelerate from Pr. 20 Acceleration/deceleration reference speed to a stop.
Acceleration time
in low-speed range
Slope set by Pr. 791
REMARKS
 The RT signal acts as the second function selection signal and makes the other second function valid. (Refer to page
120.)
 If the Pr. 20 setting is changed, the Pr. 125 and Pr. 126 (speed setting signal gain speed) settings do not change. Set Pr. 125
and Pr. 126 to adjust the gains.
 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.
 If the acceleration/deceleration time is set, the actual motor acceleration/deceleration time cannot be made shorter than
the shortest acceleration/deceleration time determined by the mechanical system J (moment of inertia) and motor
torque.
Parameters referred to
Pr. 29 Acceleration/deceleration pattern selection
Pr. 125, Pr. 126 (speed setting gain speed)
Pr. 178 to Pr. 182 (input terminal function selection)
98
Pr. 20
Maximum operating speed
(r/min)
Acceleration time
Slope set by Pr. 7
Refer to page 152.

Deceleration time from maximum operating speed to stop
Deceleration time
Slope set by Pr. 8
Refer to page 100.
Refer to page 117.
3000r/min
Pr. 8 =
1800r/min
Low-speed range
Time
Deceleration time
in low-speed range
Slope set by Pr. 792
 10s
16.7s
Refer to
(