text: <s>[INST] PowerFlex 523 - static vs dynamic autotune IR Voltage Drop Hello, We have a few PowerFlex 523 drives, all setup in the same manner and connected to identical motors. Static autotune was done on all of them and as a result the parameter 496 (IR Voltage Drop) was automatically set by the drives to a value in the range 22-24 V, each drive having slightly different value. Then, dynamic autotune was run on two of these drives and the parameter 497 was automatically set on them as expected, but also these drives changed their parameter 496 to a completely different value - 40V. Is this normal for dynamic autotune to override parameter 496? The updated value was not just slightly different. Static autotune sets it to 23.8V, then dynamic autotune overrides it to 40V, the difference is about 16V. Is dynamic autotune able to sense the voltage drop better and hence updates this value or is this erroneous behavior? [/INST] Hi Nickolay, The Static Tune Par 70 =2 can be performed in SVC and FV modes (Par 35) no matter if motor has or not a feedback encoder. It usually gets a reasonable value for the most of applications. The Dynamic Tune Par 70 = 3 only returns valid results with FV with feedback, or SVC with uncoupled load. If your application doesn't have a feedback encoder, the best solution is the Static Tune. It is explained in page 61, speaking about the Par 70: PowerFlex 750-Series AC Drives - Programming Manual. Publication 750-PM001. Paragraph: Important: If using rotate tune for a Sensorless Vector (SV) mode, the motor should be uncoupled from the load or results may not be valid. With a Flux Vector (FV) mode, either a coupled or uncoupled load will produce valid results. \\n </s>