3 phase line filters melting out.

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lquadros

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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.
 

MrJLH

Senior Member
Location
CO
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.
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
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.
 
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Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
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.
 

Besoeker3

Senior Member
Location
UK
Occupation
Retired Electrical Engineer
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.
 

lquadros

Member
3 phase line filters melting out.

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

lquadros

Member
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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