Mitsubishi Electric FR-D720 K Series Instruction Manual page 104

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 0Hz from Pr. 20 Acceleration/deceleration reference
frequency.
Set the deceleration time according to the following formula.
Deceleration
=
time setting Maximum operating frequency - Pr. 10
Example) How to find the setting value for Pr.8 when decreasing the output
frequency from the maximum frequency of 50Hz in 10s with Pr.20 =
120Hz and Pr.10 = 3Hz.
(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 102), the acceleration/
deceleration time is the time required to reach Pr. 3 Base frequency.
 Acceleration/deceleration time formula when the set frequency is the base frequency or higher
4

t=
9
 Guideline for acceleration/deceleration time at the Pr. 3 Base frequency of 60Hz (0Hz to set frequency)
 Changing terminal assignment may affect the other functions. Set parameters after confirming the function of each
terminal.
REMARKS
 The RT signal acts as the second function selection signal and makes the other second functions valid. (Refer to page 119.)
 If the Pr. 20 setting is changed, the Pr. 125 and Pr. 126 (frequency setting signal gain frequency) settings do not change.
Set Pr. 125 and Pr. 126 to adjust the gains.
 When the Pr. 7, Pr. 8, Pr. 44 and Pr. 45 settings are 0.03s or less, the acceleration/deceleration time is 0.04s. At that time, set Pr.
20 to "120Hz" or less.
 Any value can be set to the acceleration/deceleration time, but 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. 3 Base frequency
Pr. 10 DC injection brake operation frequency
Pr. 29 Acceleration/deceleration pattern selection
Pr. 125, Pr. 126 (frequency setting gain frequency)
Pr. 178 to Pr. 182 (input terminal function selection)
100
Pr. 20
T 5
2
 f T
+
2
9
(Pr. 3)
Frequency setting (Hz)
Acceleration/
deceleration time (s)
5
15
Refer to page 88.
Refer to page 112.

Deceleration time from maximum operating frequency to stop
T: Acceleration/deceleration time setting (s)
f: Set frequency (Hz)
60
5
15
Refer to page 102.
Refer to page 156.
Refer to page 116.
120Hz
 10s
Pr. 8 =
50Hz - 3Hz
120 200 400
12 27 102
35 82 305
25.5s