Sigma-II Series SGM*H/SGDH USER'S MANUAL - Esco Drives ...

10 Inspection, Maintenance, and Troubleshooting10.1.7 Troubleshooting for Malfunction without Alarm DisplayTable 10.8 Troubleshooting for Malfunction without Alarm Display (Cont’d)SymptomOvertravel(OT)(Movementover the zonespecified bythe host controller)Position error(withoutalarm)CauseAn overtravel signal is output (P-OT(CN1-42) or N-OT (CN1-43)) is atH.The overtravel signal does not operatenormally (P-OT or N-OT signalsometimes changes).Incorrect P-OT/N-OT signal selectionIncorrect servomotor stop methodselectionImproper overtravel position settingNoise interference due to improperencoder cable specificationsNoise interference because theencoder cable distance is too long.Noise influence due to damagedencoder cableExcessive noise interference toencoder cableFG electrical potential varies byinfluence of such machines on theservomotor side as welders.SERVOPACK pulse count error dueto noiseExcessive vibration and shock to theencoderCheck if the voltage of input signal externalpower supply (+24 V) is correct.Check if the overtravel limit switch (SW)operates properly.Check if the overtravel limit switch (SW) isconnected correctly.Check the fluctuation of the input signalexternal power supply (+24 V) voltage.Check if the overtravel limit switch (SW)activate correctly.Check if the overtravel limit switch wiringis correct. (check for damaged cables orloosen screws.)Check the P-OT signal selection (Pn50A.3).Check the N-OT signal selection(Pn50B.0).Check if “coast to stop” in servo OFF statusis selected.Check if “coast to stop” in torque controlmode is selected.The distance to the position of OT(overtravel) is too short considering thecoasting distance.The encoder cable specifications must be:Twisted-pair or twisted-pair shielded wirewith core 0.12 mm 2 (0.0002 in 2 ) min. andtinned annealed copper twisted wire.The wiring distance must be 20 m (65.6 ft)max.Check if the encoder cable is bent or itssheath is damaged.Check if the encoder cable is bundled with ahigh-current line or near high-current line.Check if the machine is correctly grounded.Check if the signal line from the encoder isinfluenced by noise.Machine vibration occurred or servomotormounting such as mounting surface precision,fixing, alignment is incorrect.Connect to the external +24 V power supply.Correct the overtravel limit SW.Correct the overtravel limit SW wiring.Stabilize the external +24 V power supply voltage.Adjust the overtravel limit SW so that it operates correctly.Correct the overtravel limit SW wiring.Correct the setting of P-OT signal selection (Pn50A.3).Correct the setting of N-OT signal selection (Pn50B.0).Check Pn001.0 and Pn001.1.Check Pn001.0 and Pn001.1.Correct the OT position.Use encoder cable with the specified specifications.The encoder cable distance must be within the specifiedrange.Correct the encoder cable layout.Change the encoder cable layout so that no surge isapplied.Ground the machine separately from PG side FG.Take a measure against noise for the encoder wiring.Reduce the machine vibration or mount the servomotorsecurely.Encoder fault An encoder fault occurred. Replace the servomotor.SERVOPACK fault A SERVOPACK fault occurred. Replace the SERVOPACK.Unsecured coupling betweenmachine and servomotorNoise interference due to improperinput signal cable specificationsNoise interference because the inputsignal cable distance is too long.Encoder fault (pulse count does notchange)InspectionCorrective Actions: Turn OFF the servo system before executing operations.Check if a position error occurs at the couplingbetween machine and servomotor.The input signal cable specifications mustbe:Twisted-pair or twisted-pair shielded wirewith core 0.12 mm 2 (0.0002 in 2 ) min. andtinned annealed copper twisted wire.The wiring distance must be 3 m (9.84 ft)max. and the impedance several hundredsohm max.An encoder fault occurred. (pulse countdoes not change)Secure the coupling between the machine and servomotor.Use input signal cable with the specified specifications.The input signal cable distance must be within the specifiedrange.Replace the servomotor.10-20