Machine Protection
6-
49
Machine Protection
This section explains functions for protecting the machine.
Limiting Motor Torque (Torque Limit Function)
The motor torque limit function is enabled with
open-loop vector control.
In the open-loop vector control
the user-set value is applied to the torque limit by cal-
culating internally the torque output by the motor. Enable this function if you do not want a torque above a
specified amount to be applied to the load, or if you do not want a regeneration value above a specified
amount to occur.
Related Constants
Con-
stant
Num-
ber
Name
Description
Setting
Range
Factory
Setting
Change
during
Opera-
tion
Control Methods
MEMO
BUS
Regis-
ter
V/f
V/f
with
PG
Open
Loop
Vec-
tor
Flux
Vec-
tor
L7-01
Forward
drive torque
limit
Sets the torque limit value as a percent-
age of the motor rated torque.
Four individual regions can be set.
0 to
300
200%
No
No
No
A
A
4A7H
L7-02
Reverse
drive torque
limit
0 to
300
200%
No
No
No
A
A
4A8H
L7-03
Forward
regenera-
tive torque
limit
0 to
300
200%
No
No
No
A
A
4A9H
L7-04
Reverse
regenera-
tive torque
limit
0 to
300
200%
No
No
No
A
A
4AAH
L7-06
Integral
time setting
for torque
limit
Set the integral time for the torque
limit. When integral control is set for
the torque limit, reduce this setting to
increase the change in frequency for the
torque limit.
5 to
10000
200 ms
No
No
No
A
No
4ACH
L7-07
Control
method
selection
for torque
limit dur-
ing acceler-
ation and
deceleration
Select the control method for the torque
limit during acceleration and decelera-
tion.
0: Proportional control (integral
control during constant speed)
1: Integral control
Usually, this constant does not need to
be set.
For applications in which the torque
limit will be reached during accelera-
tion and deceleration, torque control
can be given priority by selecting inte-
gral control.
When the torque is limited, the acceler-
ation and deceleration times may
increase or the motor speed may not
agree with the speed reference value.
0 or 1
0
No
No
No
A
No
4C9H
flux vector control and
and flux vector control,
Output torque
Positive torque
Reverse
Negative torque
No. of
motor
rotations
Regenerative
state
Regenerative
state
Forward
