Mitsubishi FR-F720-00046-NA Instruction Manual page 116

Setting of acceleration/deceleration time
and acceleration/deceleration pattern
Setting value "2"
[S-pattern acceleration
/deceleration B]
f1
f2
Time
Setting value "3"
[Anti-backlash measure
function]
Pr. 140
Pr. 13
Pr. 143
Pr. 141
Setting value "6"
[Variable-torque
acceleration/deceleration]
Setting
frequency
Pr.3
Base frequency
Pr.8 Deceleration time
Pr.7 Acceleration time
CAUTION
Setting the backlash measures increases the acceleration/deceleration time by the stopping time.
♦ Parameters referred to ♦
Pr. 3 Base frequency Refer to page 89
Pr. 7 Acceleration time, Pr. 8 Deceleration time, Pr. 20 Acceleration/deceleration reference frequency
Pr. 14 Load pattern selection
106
(3) S-pattern acceleration/deceleration B (Pr. 29 = "2")
⋅ For prevention of load shifting in conveyor and other applications. Since
acceleration/deceleration is always made in an S shape from current
frequency (f2) to target frequency (f1), this function eases shock produced at
acceleration/deceleration and is effective for load collapse prevention, etc.
(4) Backlash measures (Pr. 29 = "3", Pr. 140 to Pr. 143)
⋅ What is backlash?
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
Pr. 142
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.
Time
143.
(5) 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.
In areas where output frequency > base frequency, the speed accelerates/
decelerates linearly.
CAUTION
⋅
As the acceleration/deceleration time of variable-torque acceleration/deceleration,
set the time taken to reach Pr. 3 Base frequency, not Pr. 20 Acceleration/deceleration
Time
reference frequency.
REMARKS
⋅
When the base frequency is not 45 to 65Hz, the speed accelerates/decelerates linearly
even though Pr. 29 = "6".
⋅
Variable-torque acceleration/deceleration overrides Pr. 14 = "1" setting (for variable-
torque load). Thus, when Pr. 14 = "1" while variable-torque acceleration/deceleration is
valid, inverter operates as Pr. 14 = "0" (for constant-torque load).
Refer to page 91
Refer to page 101