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Capacitor Reforming, why it's needed?
3

Capacitor Reforming, why it's needed?

Capacitor Reforming, why it's needed?

(OP)
Can anybody give me an Idea that why capacitor reforming is needed in the cases where a drive has been sitting on shelf for too long? I want to know what changes in capacitor if it's not been used for a long time? Is this required only for the capacitors which are connected to power circuit or is it needed for all the capacitors including the ones which are on control circuit boards?

RE: Capacitor Reforming, why it's needed?

Yep. So wherever they are could use the reforming method.  It becomes hard to do on the logic boards.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Capacitor Reforming, why it's needed?

Reforming is mostly (only, I would say) used for DC link capacitors in frequency inverters. I have seen an inverter where a rather big capacitor exploded when the inverter was started without reforming the capacitors. Loud bang, lots of aluminum foil all over the place and a big dent in the panel's door.

If the manufacturer says it shall be done - then do it.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Capacitor Reforming, why it's needed?

Here is a decent article on capacitor reforming which should answer many of your questions.

Also, consult the drive manufacturer's documentation, or give their engineering department a call. I know ABB goes into this in one of their PDF tech papers, and the manufacturer may have a specific procedure they prefer to follow.  

RE: Capacitor Reforming, why it's needed?

Dayymn. Does this apply to power factor capacitors too ? In my rewind shop, I have over 500 KVAR pf correction capacitors which lie unpowered for days together and are used only during motor testing. Of course, when they are used, the voltage is applied gradually through a variac (to reduce motor inrush current) but typical time to reach full voltage level could be as low as a minute. Should I take more time in "reforming" these caps ?

 

Muthu
www.edison.co.in

RE: Capacitor Reforming, why it's needed?

No edison. It only applies to electrolytic capacitors. All AC capacitors are either paper or film type. So no need to worry.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Capacitor Reforming, why it's needed?

Thanks Gunnar. Phew ...

Muthu
www.edison.co.in

RE: Capacitor Reforming, why it's needed?

Typically it is with VFD's where the unit has been unpowered for 2 years or so. A gentle introduction to the electrical world via a variable voltage is advised, for a few hours or so before applying full voltage.
 

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