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I have been reading up on DC bus overvoltage VFD faults. My VFD shuts down while running. From what I have read, this commonly happens when a VFD is decelerating, however we are running the VFD in local and selecting a Frequency to run at. There is no modulation to the frequency, no 4-20ma input to change the frequency while we are running. The over voltage trip point should be 810v, but when I do a fault trace, the VFD can show me what what happening at the time of the fault. My DC bus voltages (on three different fault occurrences) were 715, 745 and 785, which are all below the trip point but still higher that normal (typically around 640). Also I have two VFDs being fed by the same power source. The other unit has ran over 800 hours without a single fault. The nuisance VFD may run for several hours to a day without faulting but then may fault several times in a short time frame, always the same fault, dc bus over voltage.