# Mitsubishi Electric FR-F820-00046 Instruction Manual Page 222

Fr-f800 series.

NOTE
• When the RT signal turns ON during acceleration or deceleration with the S-pattern acceleration/deceleration B enabled, a
pattern of acceleration or deceleration changes to linear at the moment.
 Backlash measures (Pr.29 = "3", Pr.140 to Pr.143)
• Reduction gears have an engagement gap and have a dead zone between forward rotation and reverse rotation. This dead
zone is called backlash, and this gap disables a mechanical system from following motor rotation. More specifically, a
motor shaft develops excessive torque when the direction of rotation changes or when constant-speed operation shifts to
deceleration, resulting in a sudden motor current increase or regenerative status.
• To avoid backlash, acceleration/deceleration is temporarily stopped. Set the acceleration/deceleration stopping frequency
and time in Pr.140 to Pr.143.
[Anti-backlash measure
function]
Pr. 140
Pr. 13
Pr. 141
Pr. 143
NOTE
• Setting the backlash measures increases the acceleration/deceleration time by the stopping time.
 Variable-torque acceleration/deceleration (Pr.29 = "6")
• This function is useful for variable-torque load such as a fan and blower to accelerate/decelerate in short time.
Linear acceleration/deceleration is performed in the area where the output frequency > base frequency.
[Variable-torque acceleration/deceleration]
Output frequency
Set frequency
Pr.3 Base frequency
Pr.7
Acceleration time
NOTE
• When the base frequency is out of the range 45 to 65 Hz, the linear acceleration/deceleration is performed even if Pr.29 = "6".
• Even if Pr.14 Load pattern selection = "1 (variable torque load)", variable torque acceleration/deceleration setting is
prioritized and the inverter operates as Pr.14 = "0 (constant torque load)".
• For the variable torque acceleration/deceleration time setting, set the time period to reach Pr.3 Base frequency. (Not the time
period to reach Pr.20 Acceleration/deceleration reference frequency.)
• The variable torque acceleration/deceleration is disabled during PM motor control. (Linear acceleration/deceleration is
performed.)
Parameters referred to
Pr.3 Base
frequencypage 528
Pr.7 Acceleration time, Pr.8 Deceleration time, Pr.20 Acceleration/deceleration reference
Pr.10 DC injection brake operation
selectionpage 530
Pr.178 to Pr.189 (Input terminal function
Pr. 142
Time
Time
Pr.8
Deceleration time
frequencypage 535
selection)page 355
5.5 (F) Setting of acceleration/deceleration time and acceleration/deceleration pattern
frequencypage 216
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5. PARAMETERS  