Mitsubishi Electric 800 Series Instruction Manual page 272

(F) Setting of acceleration/deceleration time and acceleration/deceleration pattern
Deceleration time setting (Pr.8, Pr.20)
• Use Pr.8 Deceleration time to set the deceleration time required to reach a stop status from to Pr.20 Acceleration/
deceleration reference frequency.
• Set the deceleration time according to the following formula.
Deceleration time setting = Pr.20  deceleration time from maximum frequency to stop / (maximum frequency - Pr.10)
• For example, the following calculation is used to find the setting value for Pr.8 when increasing the output frequency to the
maximum frequency of 50 Hz in 10 s with Pr.20 = 120 Hz and Pr.10 = 3 Hz.
Pr.8 = 120 Hz  10 s / (50 Hz - 3 Hz)
25.5 s
NOTE
• 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.
• 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.
• Under PM sensorless vector control, if the protective function (E.OLT) is activated due to insufficient torque in the low-speed
range, set longer acceleration/deceleration times only in the low-speed range in Pr.791 Acceleration time in low-speed
range and Pr.792 Deceleration time in low-speed range.
Changing the minimum increment of the acceleration/deceleration time
(Pr.21)
• Use Pr.21 to set the minimum increment of the acceleration/deceleration time.
Setting value "0" (initial value): minimum increment 0.1 s
Setting value "1": minimum increment 0.01 s
• Pr.21 setting allows the minimum increment of the following parameters to be changed.
Pr.7, Pr.8, Pr.16, Pr.44, Pr.45, Pr.110, Pr.111, Pr.264, Pr.265, Pr.791, Pr.792
NOTE
• Pr.21 setting does not affect the minimum increment setting of Pr.611 Acceleration time at a restart.
• The parameter can be set in five digits including the numbers below decimal point for the FR-PU07. A "1000" or more value is
set in increments of 0.1 s even if Pr.21 = "1".
271
PARAMETERS
5
GROUP
F