text: <s>[INST] F4 fault Summary: powerflex 4M series fault F4 hello, anyone ever experienced  f4  fault on 4M series ? The manual says plus/minus %10 devitation in supply voltage is acceptable. Measured AC supply voltage with an power quality analyzer and never found values less than 375 V. Wiring is carried out with shielded cable between drive and motor end, shield are connected to gnd as shown in manual. Any suggestions ? thank you [/INST] This problem has not been fixed. There are six drives installed in the same cabinet . Each drive has a an overload breaker on the power input side . the breaker inputs are tied with three phase a copper bus . The incoming three phase from the main cabinet breaker is also connected to breaker inputs. I have seen that when this problem occurs the voltage on the main breaker goes down, but only in this cabinet. There are other cabinet for other machines which do not see any drop in voltage. So the voltage drop is not caused by the network. Somehow voltage is pulled down in the drives cabinet, What might be the reason? I have meggered all the motors and found Ok. Could it be one drive with a defective rectifying circuit or capacitor? \\n </s>