Yaskawa YASNAC PC NC Maintenance Manual - Manual (Page 75)

PC NC Maintenance Manual Chapter 4: Troubleshooting
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AL-31:Motor overspeed
Error Contents The motor speed exceeded 120% of setting rated speed (C1-26).
Cause and measures
AL-32:The speed deviation is excessive.
Error Contents The speed became 50% or less than 25% of the command value.
Detection Methods If the following condition consists, the current is interrupted, and the
alarm is displayed. (the state which becomes speed coincidence (15%
fix) after acceleration is completed) / (the speed command is parame-
ter) / (an electric mode is specified) / (Is the orientation control operat-
ing ?) / (the speed command is less than 1/2 or 1/4 of feedbacks
[selected by C1-38.b4] ? (the above conditions were consistent with
the continued speed deviation over protect drive delay time [C1-40.b1-
b0])
Cause and measures
Cause Measures
Improper drive by noise (encoder
cable characteristic defect) Check that the encoder signal conductor is isolated from the
main circuit wiring and other power lines.
Check encoder cable specification (twisted-pair shield wire)
[recommended cable “KQVV-SW” by Fujikura-Densen Co.]
Motor encoder fault Confirm that there is no abnormal motor speed changes by the
speedometer indication or the drive state display (U1-01).
Exchange encoder or motor.
Control parameter setting is defec-
tive. Refer to the setting list for the control parameter.
Control card fault Exchange unit (exchange control card)
Cause Measures
Motor overload Is the load heavy? Check that there is no interlock of cut-
ters.
Torque limit drive Check that neither external limiting torque signal TLL nor
TLH are inputted.
Zero speed damping time (C1-35) is
set. Exceed the drive delay time of speed deviation overprotec-
tion (C1-40.b1-b0).
Control parameter setting is defective. Refer to the setting list for the control parameter.
Main circuit disconnection and improper
connection Check wiring between the inverter and the motor.
Encoder signal conductor disconnec-
tion, improper connection, and the con-
nector omission. Check encoder signal conductor wiring.