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11. CHARACTERISTICS
11. CHARACTERISTICS
11.1 Overload protection characteristics
An electronic thermal relay is built in the drive unit to protect the servo motor and drive unit from
overloads.
Overload 1 alarm (A.50) occurs if overload operation performed is above the electronic thermal relay
protection curve shown in any of Figs 11.1. Overload 2 alarm (A.51) occurs if the maximum current flows
continuously for several seconds due to machine collision, etc. Use the equipment on the left-hand side
area of the continuous or broken line in the graph.
In a machine like the one for vertical lift application where unbalanced torque will be produced, it is
recommended to use the machine so that the unbalanced torque is 70% or less of the rated torque.
The overload protection characteristic is about 20% lower than that of the MELSERVO-J2-Super series.
However, operation at the 100% continuous rating can be performed.
1000
100
10
1
0.1
0 50 150 200 250 300
Operation time [s]
100
During servo lock
During rotation
Load ratio [%]
a. MR-J2M-10DU to MR-J2M-40DU
1000
100
10
1
0.1
0 50 150 200 250 300
100
Operation time [s]
During servo lock
During rotation
Load ratio [%]
b. MR-J2M-70DU
Fig 11.1 Electronic thermal relay protection characteristics
Note. 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 30r/min or less low-speed operation status, the servo amplifier may fail even when the electronic
thermal relay protection is not activated.