Mitsubishi Electric 800 Series Instruction Manual (Function page 237

 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 the 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. (When the RT signal is turned ON, the second acceleration/deceleration
time is prioritized.)
Acceleration time
in low-speed range
Slope set by Pr. 791
NOTE
• Set Pr.791 (Pr.792) to a value larger than the Pr.7 (Pr.8) setting. 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.
 Faulty acceleration rate detection level (Pr.375)
• Under PM sensorless vector control, if the motor rotation speed exceeds the speed set in Pr.375, E.OA (Acceleration error)
is activated, and the inverter output is shut off.
• The Pr.375 setting value must be much larger than the acceleration/deceleration slope. If the Pr.375 setting value is
smaller than the acceleration/deceleration slope, E.OA (Acceleration error) is activated even during normal operation.
• If rapid acceleration/deceleration is set for normal operation and E.OA (Acceleration error) is activated, set Pr.375 = "9999"
to disable the acceleration rate error detection.
Rotation speed
0
Acceleration rate
Faulty acceleration
rate detection level
0
Faulty acceleration
rate detection level
Fault output
(ALM)
 Emergency stop function (Pr.1103)
• When the Emergency stop (X92) signal is ON, the deceleration stop is performed according to the settings in the Pr.1103
Deceleration time at emergency stop and Pr.815 Torque limit level 2.
236
10. (F) Settings for Acceleration/Deceleration
10.1 Setting the acceleration and deceleration time
Acceleration time Deceleration time
Slope set by Pr.7 Slope set by Pr.8
Speed command
Rotation speed
ON
E.OA
Low-speed range
(rated motor frequency/10)
Time
Deceleration time
in low-speed range
Slope set by Pr.792
Time
Time