Vertical Axis Freefall Prevention Function - Mitsubishi Electric MELSERVO-J4 Series Instruction Manual

Vertical axis freefall prevention function

The vertical axis freefall prevention function avoids machine damage by pulling up the shaft slightly like the following case.
When the servo motor is used for operating vertical axis, the servo motor electromagnetic brake and the base circuit shut-off
delay time function avoid dropping axis at forced stop. However, the functions may not avoid dropping axis a few m due to
the backlash of the servo motor electromagnetic brake.
The vertical axis freefall prevention function is enabled with the following conditions.
• Other than "0" is set to [Pr. PC31 Vertical axis freefall prevention compensation amount].
• EM2 (Forced stop 2) turned off, an alarm occurred, or network communication shut-off occurred while the servo motor
speed is zero speed or less.
• The base circuit shut-off delay time function is enabled.
Timing chart
EM2 (Forced stop 2)
Position
Base circuit
(Energy supply to
the servo motor)
MBR
(Electromagnetic
brake interlock)
Electromagnetic brake
Servo-on command
(from controller)
Ready-on command
(from controller)
Adjustment
• Set the freefall prevention compensation amount in [Pr. PC31].
• While the servo motor is stopped, turn off the EM2 (Forced stop 2). Adjust the base circuit shut-off delay time in [Pr. PC02]
in accordance with the travel distance ([Pr. PC31). Adjust it considering the freefall prevention compensation amount by
checking the servo motor speed, torque ripple, etc.
Residual risks of the forced stop function (EM2)
• The forced stop function is not available for alarms that activate the dynamic brake when the alarms occur.
• When an alarm that activates the dynamic brake during forced stop deceleration occurs, the braking distance until the
servo motor stops will be longer than that of normal forced stop deceleration without the dynamic brake.
• If STO is turned off during forced stop deceleration, [AL.63 STO timing error] will occur.
3 SIGNALS AND WIRING
112
3.6 Forced stop deceleration function
ON
OFF (Enabled)
Travel
distance
ON
OFF
ON
OFF (Enabled)
Release
Activate
ON
OFF
ON
OFF
Set the base circuit shut-off delay time.
([Pr. PC02])