Mitsubishi Electric MR-JE-_A, Instruction Manual

Page: 70 / 370

3. SIGNALS AND WIRING
3 - 35
(5) Torque limit
CAUTION
If the torque limit is canceled during servo-lock, the servo motor may suddenly
rotate according to position deviation in respect to the command position.
When using the torque limit, check that [Pr. PB06 Load to motor inertia ratio] is
set properly. Improper settings may cause an unexpected operation such as an
overshoot.
(a) Torque limit and torque
By setting [Pr. PA11 Forward rotation torque limit] or [Pr. PA12 Reverse rotation torque limit], torque
is always limited to the maximum value during operation. A relation between the limit value and
servo motor torque is as follows.
Torque limit value
in [Pr. PA11]
Maximum
torque
Torque
0 100 [%]
Torque limit value
in [Pr. PA12]
100
CCW direction CW direction
A relation between the applied voltage of TLA (Analog torque limit) and the torque limit value of the
servo motor is as follows. Torque limit values will vary about 5% relative to the voltage depending on
products. At the voltage of less than 0.05 V, torque may vary as it may not be limited sufficiently.
Therefore, use this function at the voltage of 0.05 V or more.
±5%
Connection example TLA applied voltage vs. torque limit value
TLA applied voltage [V]
Maximum
torque
T
or
que
0
0
0.05
Servo amplifier
24 V DC (Note)
TL
DICOM
TLA
LG
SD
0 V to +10 V
Note. This diagram shows sink I/O interface. For source I/O interface, refer to section 3.9.3.
(b) Torque limit value selection
The following shows how to select a torque limit using TL (External torque limit selection) from [Pr.
PA11 Forward torque limit] or [Pr. PA12 Reverse torque limit] and TLA (Analog torque limit).
When TL1 (Internal torque limit selection) is enabled with [Pr. PD03] to [Pr. PD22], select [Pr. PC35
Internal torque limit 2].
However, if [Pr. PA11] and [Pr. PA12] value is less than the limit value selected by TL/TL1, [Pr.
PA11] and [Pr. PA12] value will be enabled.