Characteristics; Overload Protection Characteristics - Mitsubishi Electric MELSERVO-J3 Series Handbook

Part 5: Review on Replacement of MR-J3-DU_ with MR-J4-DU_

6. CHARACTERISTICS

6.1 Overload protection characteristics

An electronic thermal relay is built in the converter unit and drive unit to protect the servo motor, converter
unit and drive unit from overloads.
[AL. 50 Overload 1] occurs if overload operation performed is above the electronic thermal protection curve
shown in fig. 5.1, 5.2 and 5.3. [AL. 51 Overload 2] occurs if the maximum current is applied continuously for
several seconds due to machine collision, etc. Use the equipment on the left-side area of the graph.
For the system where the unbalanced torque occurs, such as a vertical axis system, the unbalanced torque
of the machine should be kept at 70% or lower of the motor's rated torque.
The MR-J3-DU_ and MR-J4-DU_ servo amplifiers have servo motor overload protective function.
(1) For the MR-J3-DU_
10000
1000
100
10
1
0
Converter unit
Note 1. If operation that generates torque more than 100% of the rating is performed with an abnormally high frequency in a servo
motor stop status (servo-lock status) or in a 30 r/min or less low-speed operation status, the drive unit may malfunction
regardless of the electronic thermal protection.
2. Load ratio 100% indicates the rated output of each converter unit and drive unit. Refer to "MR-J3-_A_ /MR-J3-_B_Servo
amplifier instruction manual"
Operating
(Note 2)
100 200
Load ratio [%]
Fig. 5.1 Overload protection characteristics
10000
1000
100
Servo-lock
10
1
250 0
5 - 43
Operating
(Note 2)
100 200
Load ratio [%] (Note 1)
Drive unit
250