
APPENDIX
B–64114EN/01
G. ALARM LIST
809
No. CountermeasureDescriptionLED display
[SVU–12, SVU–20]
An overcurrent alarm is issued.
This alarm is issued when an excessively large
current flows in the main circuit.
(1) Check whether a valid motor number is specified in parameter No.30.
(2) Check whether the standard values are specified in the current control parameters for servo
control.
Correct current control is possible only when the standard values are specified for the follow-
ing parameters:
No.70, 71, 72, 78, 79, 84, 85, 86, 87, 88, 89, 90
(3) Disconnect the power line from the servo amplifier unit connector. Then, release the emergen-
cy stop state.
– If the overcurrent alarm continues to be issued, replace the servo amplifier unit.
– If no overcurrent alarm is issued, go to (4).
(4) Check the insulation between the ground and each of U, V, and W. If the insulation is satisfac-
tory, go to (5).
– If a short–circuit is detected, disconnect the power line from the motor connector. Then,
check the insulation between the ground and each of U, V, and W of the motor.
– If a short–circuit is found between the ground and U, V, or W of the motor, replace the motor.
– If the insulation is satisfactory, replace the power line.
(5) Connect the power line. Observe the waveform of the motor current (IR, IS) while the motor
is accelerating or decelerating.
– If the motor current (IR, IS) does not show a normal sine wave, replace the servo amplifier
unit.
(6) Check if the motor current (IR, IS) waveforms include noise.
– When noise is included, take an action such as making a connection to shield ground.
– When noise is not included, replace the servo amplifier unit.
(7) If (1) to (4) above are not the cause of the alarm, the pulse coder, command cable, or internal
hardware of the CNC may be defective.