Drive Acs8Acs800-104-440, 12 pulse, PM kit replaced few days back, after few days of operations observed fluctuations in DSU Dc voltage 700 to 930 V Dc, input supply 680 V AC, in two out of the 5 multidrive installed on the same bus with individual inverter and DSU for fan application. At same time observed fluctuations in Kw, Dc, and some amount in speed. System kept in manual still the same. The ready of DSMB card also goes on/ Off.
Supply variations 680 to max 687 V ac.
Replaced .DSU did. Not observe Dc variations.
Removed Dsu fuse, cards, Thyristor checked as per manual did not find any abnormalities.
What can be the cause. And check further, Just 6 Hours before one inverter IGBT had failed in another drive installed on the same bub resulting in all 5 tripping oon Dc bus overvoltage.
Hi From the description you made, in my opinion at this point you should call the ABB Service of your area, which has all the tools and skills to help you. Any attempt made without having seen your system - total configuration could be useless or even harmful for the solution of your problem