Mitsubishi Electric MR-J4W2, Instruction Manual

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14. USING A LINEAR SERVO MOTOR
14 - 27
14.4 Characteristics
14.4.1 Overload protection characteristics
An electronic thermal relay is built in the servo amplifier to protect the linear servo motor, servo amplifier and
linear 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. 14.2. [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 continuous or broken
line in the graph.
Use the linear servo motor with 70% or less of the effective load ratio when it is in the servo lock state or in a
small reciprocating motion.
This servo amplifier has solid-state linear servo motor overload protection. (The servo motor overload
current (full load current) is set on the basis of 120% rated current of the servo amplifier.)
1000
100
10
1
0.1
0 50 150 200 250 300 100
Operation time [s]
Load ratio [%]
Servo-lock
Operating
1000
100
10
1
0.1
0 200 300 400 100
Operation time [s]
Load ratio [%]
Operating
Servo-lock
a. LM-H3 series
LM-K2 series
b. LM-U2 series
Fig. 14.2 Electronic thermal relay protection characteristics