Is metal/alu-can type capacitor more rugged?

[shlim]

How true is that a metal/aluminium type enclosure capacitor is more rugged as compared to a plastic can/enclosure, generally? I cannot find any reference on the Internet.

Thanks in advance.

 

[ScottyUK]

Untrue, I would say. The electrically rugged self-healing film types are almost exclusively plastic cased. The metal case offers little mechanical protection.

 

[Skogsgurra]

As Scotty says. Unless we are talking self-healing power capacitors for PF compensation. They are almost always steel encapsulated. But not for ruggedness in the first place, I think it is more about cooling and mounting.


Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[shlim]

What if I compared both types of capacitor in the aspect of fire risk? Would the metal-can type somehow prevented the spread of fire in the event of failure from the component internally? Is there any reference I can refer to?

 

[Comcokid]

What exactly do you mean by rugged?

Electrolytic capacitors (metal can type you refer to???) wear out over time - period. They are never fully sealed as they very slowly produce hydrogen from the breakdown of the electrolyte. Almost all of this type are DC only.

Plastic capacitors, if your are referring to rectangular film capacitors, can have extremely long lifetimes. Film capacitors are not polarized and handle AC currents as well as DC currents. Some types of film capacitors are self-healing when exposed to short overvoltage spikes.

Now, if your are talking about oval can capacitors like motor-start or motor-run capacitors, these are film capacitors, however they are made to be inexpensive, and do sometimes eventually fail.

 

[shlim]

Comcokid, what I'm trying to find out is that in an event of internal failure of a capacitor, would a metal-can type able to 'suppress' the damage (by keeping it internally), as compared to a plastic-can type (which may burn)? Or, which type will tends to fail more catastrophically had they failed in the similar nature of event?

 

[ScottyUK]

I have seen many of both types which have suffered disruptive failures. Metal cans certainly don't contain the problem, they just tend to result in the mess being ejected out of the terminal end where the capacitor is weaker, while plastic-cased types are less predictable. That said I have seen metal can designs of both electrolytic and film types where the can itself has ruptured or split. Plastic types do tend to shatter in the event of heavy internal faults. The problem with electrolytics is that they tend to eject stinking corrosive material over everything in the local area, whereas film types tend to eject charred fragments.

 

[Skogsgurra]

You need to talk to the manufacturer about this. There are no general rules that I know of. It depends a lot on what power levels are involved, circuit impedance and what protection is used.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[MacGyverS2000]

Scotty got my reply in his last sentence... do you want (mildly) corrosive liquid dispersed over a local area or do you want charred chunks? You only get to pick the manner of their eventual execution, but they WILL eventually give up the ghost.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[shlim]

Noted, thanks all for the inputs.