text: <s>[INST] Powerflex700VC Encoder Loss Flt 91 Summary: PowerFlex700VC FLT 91 Encoder Loss FaultGood day! One of our electrical hoists is tripping from time to time with FLT 91 Encoder Loss Fault. Sometimes it happens during lifting and hoisting up/down with or without load and sometimes even without using it. The system has been working for 10 years without any issue, it just started last month. I have changed the encoder, encoder connector, encoder card and checked all the wirings interconnections but so far, no luck. The length of the encoder cable (festoon) is around 100 meters. Out of frustration I’m now planning to change the VFD and cassette control card, but I really don’t think that they are the culprit. Another thing is to change the cable, but this is a very big job. I’m lost to what I do next and in need someone expert advise. Thanks, Ian [/INST] I don't think this is a VFD problem. Could be cassette, but more likely I think you have a cable problem. You've changed everything else directly related to the encoder; I'd lean towards a cable conductor fracture. Before replacing the cable, can you do a close inspection of it, including tactile? One other place to look would be the power supply feeding the encoder. Do you have proper voltage all the way out at the encoder? If you're not externally powering the encoder (using the cassette), then replacing the cassette might do the trick. How often does the failure occur now, and when (or WHERE in the hoist motion) does it occur? \\n </s>