Electronic – Why do the capacitors inside the inverter heat up

capacitorinverteroverheat

I'm having a problem with the inverters of textile machinery. The machine I work with is the Rieter brand Ring machine and the main inverter, the part is defined as 75 kw U1. 12 units 2200 uf 400 volt capacitor inside the inverter and sometimes capacitors from the condenser block often overheat and then break. When I replace the deteriorating capacitor, the fault usually goes away. There are 20 textile machine so each month an inverter is breaks. But I can't figure out what caused the heatimg. The inverter has fluid circulation and fan system inside and operates.

What is the function of 12 pieces 2200 uf 400 volt capacitors in the inverter, and do you have any idea why the capacitors are heating up?

Best Answer

why the (large line voltage rectified electrolytic) capacitors are heating up?

  • under-rated inverter for motor load
  • lack of VSD VFD control method to prevent surges.
  • Unskilled maintenance on critical parts.
    • caps like batteries need to all replaced if in parallel like batteries in series in order to share the load equally.
    • not all caps. are created equal
      • they have life test temperature ratings of 1kh to 5k hours at 85'C to 115'C
      • they have different ESR ratings or loss tangent that affects temp rise. Pd=I^2*ESR
      • the best e-caps only only come from companies in Japan and S. Korea.
      • electrolytic caps are like Lithium batteries and demand highest quality process design and materials for low ESR.
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