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    3 phase line filters melting out.

    3 phase line filters have failed/ melted due to supposedly capacitor failures within these filters. What would be the reasons that it would do so?
    Any answers would be greatly appreciated.

    #2
    Originally posted by lquadros View Post
    3 phase line filters have failed/ melted due to supposedly capacitor failures within these filters. What would be the reasons that it would do so?
    Any answers would be greatly appreciated.
    How old are the capacitors? I had a motor starter that melted that had starting capacitors. Capacitors fail just like any other electric components. Depending on how old the capacitors are the electrolytic could of deteriorated.

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      #3
      Originally posted by lquadros View Post
      3 phase line filters have failed/ melted due to supposedly capacitor failures within these filters. What would be the reasons that it would do so?
      Any answers would be greatly appreciated.
      What kind of load do you have on the filter outputs? High frequency content from nonlinear loads or other sources may cause large currents to flow through the capacitors because of their decreasing impedance as the frequency goes up. High currents will heat capacitors because of their series resistance (which is spec'ed as their ESR or equivalent series resistance).

      Or is the line filter on the output of a VFD or other source with higher frequency switching content? The same effect can occur due to high currents in the capacitors. The filter should have series inductors, at least on the side where the high frequency content originates, in order to limit the current going through the capacitors.
      Last edited by synchro; 07-16-19, 05:10 PM.

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        #4
        What are these "filters" anyway? Are they one of these snake-oil magic box products that was supposedly going to save them energy? Those things are all total junk, not worth the time to install them.
        __________________________________________________ ____________________________
        Many people are shocked when they discover I am not a good electrician...

        I'm in California, ergo I am still stuck on the 2014 NEC... We'll get around to the 2017 code in around 2021.

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          #5
          Originally posted by lquadros View Post
          3 phase line filters have failed/ melted due to supposedly capacitor failures within these filters. What would be the reasons that it would do so?
          Any answers would be greatly appreciated.
          I have seen harmonics from non-linear loads cause that.

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            #6
            3 phase line filters melting out.

            The 3phase line filter is connected to 6 axis servo motors. A robot. The load is non-linear.

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              #7
              Originally posted by lquadros View Post
              The 3phase line filter is connected to 6 axis servo motors. A robot. The load is non-linear.
              Seems like a probable cause. I used to use de-tuning reactors.

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                #8
                3 phase line filters melting out.

                At the moment, the focus is on Harmonics. I need to understand more about this. The solution arranged is to install the line filter on the secondary side of the transformer instead of Primary. Any ideas?

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