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3/27/2011 8:37 AM | |
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Hi We got 2 pairs of Liquid Cooled rectifiers connected on the same DC-link. Two and tworectifiers in parallel. Water cooleds120 (BLM)1370KW*2, on each pair. Se attached drawing. Both pairs are each controlled by a CU320. They have been working fine for a year now, but suddenly both units are failing. When we start them up we get "AlarmA05053 (F) Parallel circuit: Inadmissible DC link voltagedissymmetry" and after two seconds the fault "F30027 Power unitprecgarging DC link time monitoring" comes and the alarm disapears. We can also observe that only one rectifier on each pair goes into fault, as the LED turns red on one rectifier and stays green on the other. We have tried to disconnect all inverters connected to the DC-link, to rule out faults related to the inverters. Wemeasure726V AC on the incoming connection side of the rectifiers. The attached Tracemeasure number one is fromthese rectifiers during startup, you can see that it goes from500V dc directly up to1000V DC in 0 ms before it shuts down.Measure number two is from a healthy unit on aseparate DC-link, this is how it suppose to be. AttachmentMain circuit diagram Drilling SWBD Bus A.zip (171 Downloads) |
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