#Variablespeeddrives #casestudy #preventivemaintenance #630 KW
During a break down of a 630 KW Ac drives, we observed the silicone gel leaked out from U phase IGBT’s. Silicone gels provide the dielectric insulation in insulated gate bipolar transistor (IGBT) power modules to prevent partial discharge, inhibit moisture ingress and keep out contaminants from the internal circuitry. The junction temperatures of these power modules are located between 150 o C and 175 o C and these temperatures will increase to 200 o C in the near future. I would like to share our observations of this particular case. A. Temperature sensors of all 3 phases found proper. Resistance was approx. 4.71 K ohms. B. Silicone gel leaked out from 6 IGBTS of U phase. C. Drive overheat protection was bypassed. So drive was not tripping at high temperature. D. Temperature sensing circuit’s track was damaged. So we replaced the gate drive board of particular section. E. Heat sink vents was completely choked. We cleaned it by forced