Overload Protection Characteristics - Mitsubishi Electric MELSERVO-J4 Series Transition Handbook

Part 7: Common Reference Material

1.3 Overload protection characteristics

An electronic thermal is built in the servo amplifier to protect the servo motor, servo amplifier and servo
motor power wires from overloads.
[AL. 50 Overload 1] occurs if overload operation performed is above the electronic thermal protection curve
shown in fig. 10.1 [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-hand side area of the continuous or
broken line in 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 less of the rated torque.
This servo amplifier has solid-state servo motor overload protection.
POINT
"Overload protection characteristics" may be different due to the replacement of
the servo amplifier and the servo motor. Check "overload protection
characteristics" of each model before considering replacement.
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 50 r/min or less (the other motors: 30 r/min or less) low-speed
operation status, the servo amplifier may malfunction regardless of the
electronic thermal protection.
When MR-J4 series is driven with motors before replacement, the "overload
protection characteristics" is the same as MR-J3 series.
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