FAQ: What are some remedies to an A.C9 (Encoder Communications) alarm?
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The Sigma II User manual points out how to start troubleshooting. The most likely causes to A.C9 (AC9) alarms are:
A.C9 Alarm Causes:
A) Wiring issue causing electrical noise to enter the system
B) Defective encoder board on the motor
C) Defective amplifier
A) Wiring issue causing electrical noise to enter the system
If the system is faulting out on an A.C9 alarm while the servo is operating, the system wiring should be reviewed. The most common source of this error is due to poor installation. The overall system ground should be first checked and verified against recommended installation procedures in the manual. In the event that this alarm does occur, if it is random, the encoder cable and its installation should be examined next.
1) Check to insure the cable is wired according to the Yaskawa Manual
2) SGMG, SGMGH, SGMS, SGMSH encoder cables should be shielded on both ends of the cable
3) When dealing with longer encoder lengths, its important that larger size wire is used for the encoder +5VDC power and common (to prevent IR drop). See Yaskawa manual for special cable to suit this.
Assuming the encoder cable is electrically o.k., consider the following:
1) Are the encoder cable and power cable running the same conduit? If yes, separate them.
2) If the power and encoder cables are already running at least 10" apart, or the encoder cable must share conduit with other signal lines, try installing a ferrite core (YEA p/n ESD-SR25) at each end of the encoder cable. This will effectively increase the high frequency impedence, improving the system noise immunity.
3) If the amplifier is a 400V SGDH, and is 6kw and higher, a separate isolated 24VDC control power supply is required for each unit.
The ferrite core clamps easily on to the cable and dampens high frequency noise which can cause the A.C9 alarm. This is a low cost (less than $10) solution that often does the trick.
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Please read and understand the product instruction manual before installing, servicing or operating Yaskawa products. FAQ content and illustrations are provided as technical advice to augment the information in manual, not supersede it. It is not possible to give detailed instructions for all types of installation or support activities. The information described in the FAQs are subject to change without notice to improve the product or FAQ. Yaskawa assumes no responsibility for errors or omissions or damages resulting from the use of the information contained in any FAQ. All warnings, cautions and product instruction for product use must be followed. Installation, operation and maintenance should be carried out by qualified personnel. Failure to observe these and other precautions highlighted in the product manuals will expose the user to high voltages resulting in, serious injury or death. Qualified personnel are defined as individuals who are familiar with the installation, starting, operation and maintenance of Yaskawa products of the type described and have proper qualifications to perform the work.
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Waukegan, IL 60085