YASKAWA SGD7S-*A20**F62 Series Product Manual

Contents

5.7 Troubleshooting Based on the Operation and Conditions of the Servomotor5 Maintenance5-53AbsoluteEncoderPositionDeviationError (Thepositionthat wassaved in thehost con-troller whenthe powerwas turnedOFF is dif-ferent fromthe posi-tion whenthe powerwas nextturned ON.)Noise interference occurredbecause of incorrect EncoderCable specifications.Check the Encoder Cableto see if it satisfies speci-fications. Use shieldedtwisted-pair cables orscreened twisted-paircables with conductors ofat least 0.12 mm 2(stranded wire).Use cables that satisfythe specifications. –Noise interference occurredbecause the Encoder Cableis too long.Check the length of theEncoder Cable.• Rotary Servomotors:The Encoder Cablelength must be 50 mmax.• Linear Servomotors:Make sure that theSerial Converter Unitcable is no longerthan 20 m and thatthe Linear EncoderCable and the SensorCable are no longerthan 15 m each.–Noise interference occurredbecause the Encoder Cableis damaged.Check the Encoder Cableto see if it is pinched orthe sheath is damaged.Replace the EncoderCable and correct thecable installation envi-ronment.–The Encoder Cable was sub-ject to excessive noise inter-ference.Check to see if theEncoder Cable is bundledwith a high-current line orinstalled near a high-cur-rent line.Correct the cable lay-out so that no surge isapplied by high-currentlines.–There is variation in the FGpotential because of theinfluence of machines on theServomotor side, such as awelder.Check to see if themachines are correctlygrounded.Properly ground themachines to separatethem from the FG ofthe encoder.–There is a SERVOPACKpulse counting error due tonoise.Check to see if there isnoise interference on theI/O signal line from theencoder or Serial Con-verter Unit.Implement counter-measures against noisefor the encoder orSerial Converter Unitwiring.–The encoder was subjectedto excessive vibration orshock.Check to see if vibrationfrom the machineoccurred.Check the Servomotorinstallation (mounting sur-face precision, securingstate, and alignment).Check the linear encoderinstallation (mounting sur-face precision and secur-ing method).Reduce machine vibra-tion. Improve themounting state of theServomotor or linearencoder.–A failure occurred in theencoder. – Replace the Servomo-tor or linear encoder. –A failure occurred in the SER-VOPACK. – Replace the SERVO-PACK. –Continued on next page.Continued from previous page.Problem Possible Cause Confirmation Correction Reference