Hello masters, I am facing a problem in a factory that i am working with that its strange. They bought a machine with three cabinets full of siemens product. Every of them has almost 15 G120c inverters for every motor on the machine. The strange is that only one of those three has a serious problem on all of the G120c inverters. After one month of working on the line day by day after power down and power up they started have an alarm on one of the inverters F1600- F1611. The programmers went online and couldnt reset those alarms. In two months all of the 15 inverters got that alarm and got replaced by the machine's factory. First of all i need to mention that after 3 or 4 broken inverters i got a call to go and check them so i  started trying reset the alarm but it wasnt possible, so i powered down and power up again the cabinet and  i saw smoke on one of the inverter from the side of Bop and the inverter became fault with 1600-1611 alarm. This keeps happening for months now and we cant understand what is going wrong and only one of the three same cabinets makes this thing.  I need to mention that power supply is 24 stable from siemens , moreover has a siemens module that protects 24dc amperes and separates the 24dc safety line for Sto inputs of the inverters. All of the inverters are communicating by profinet , on the terminals they have connected only 24Dc power supply and the two stos Di4 and Di5.\\

Thank you indvance,