Mitsubishi Electric FR-A720-00030-NA Instruction Manual page 187

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
=
Maximum operating
time setting
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) Change the setting range and increments of the acceleration/deceleration time (Pr. 21)
 Use Pr. 21 to set the acceleration/deceleration time and minimum setting range.
Setting 0 (initial value)......................0 to 3600s (minimum setting increments 0.1s)
" "
Setting 1 ...........................................0 to 360s (minimum setting increments 0.01s)
" "
CAUTION
 Changing the Pr. 21 setting changes the acceleration/deceleration time setting (Pr. 7, Pr. 8, Pr. 16, Pr. 44, Pr. 45, Pr. 110, Pr. 111, Pr.
264, Pr. 265).
(The Pr. 611 Acceleration time at a restart setting is not affected.)
<Example>
When Pr. 21 = "0", setting "5.0" s in Pr. 7 and "1" in Pr. 21 automatically changes the Pr. 7 setting to "0.5" s.
(4) Set multiple acceleration/deceleration time (RT signal, Pr. 44, Pr. 45, Pr. 110, Pr. 111)
 Pr. 44 and Pr. 45 are valid when the RT signal is ON, and Pr. 110 and Pr. 111 are valid when the X9 signal is ON.
When both the RT and X9 are ON, Pr. 110 and Pr. 111 are valid.
 For the terminal used for X9 signal input, set "9" in any of Pr. 178 to Pr. 189 (input terminal function selection) to assign
the function.
 When "9999" is set in Pr. 45 or Pr. 111, the deceleration time becomes equal to the acceleration time (Pr. 44, Pr. 110).
 When Pr. 110 = "9999", third acceleration/deceleration time is invalid.
CAUTION
 In S-shaped acceleration/deceleration pattern A (refer to page 178), the set time is the period required to reach the base
frequency set in Pr. 3 Base frequency.
 Acceleration/deceleration time formula when the set frequency is the base frequency or higher
4 T

t =
f
2
9
(Pr. 3)
 Guideline for acceleration/deceleration time when Pr. 3 Base frequency = 60Hz (0Hz to set frequency)
Frequency setting (Hz)
Acceleration/
deceleration time (s)
 The RT, X9 signal can be assigned to the input terminal using any of Pr. 178 to Pr. 189 (input terminal function selection). When
terminal assignment is changed, the other functions may be affected. Set parameters after confirming the function of each
terminal.
REMARKS
 The RT (X9) signal acts as the second (third) function selection signal and makes the other second (third) function valid. (Refer
to page 239)
 The RT signal is assigned to the RT terminal in the default setting. By setting "3" in any of Pr. 178 to Pr. 189 (input terminal
function selection), you can assign the RT signal to the other terminal.
 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, Pr. 45, Pr. 110 and Pr. 111 settings are 0.03s or less, the acceleration/deceleration time is 0.04s
(under V/F control, Advanced magnetic flux vector control). At that time, set Pr. 20 to "120Hz" or less.
 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. 3 Base frequency Refer to page 161
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. 189 (input terminal function selection)
176
Pr. 20
Deceleration time from maximum

operating frequency to stop.
5
T T: Acceleration/deceleration time setting value(s)
2
+
f : Set frequency(Hz)
9
60
5 5
15 15
Refer to page 206
Refer to page 178
Refer to page 299
Refer to page 235
Pr. 8 =
120 200 400
12 27 102
35 82 305
120Hz
 10s
25.5s
50Hz - 3Hz