AC (motor) capacitor

[Noway2]

I am looking for two AC film capacitor, a 35uF at 370Vac, ~6.35A rms and a 70uF at 330Vac ~11.3A rms, with SCREW TERMINALS.

I have looked through the catalogs of several manufacturers, Cornell, GE, Aerovox, Mallory, Vishay, etc and while I am comming up with plenty of AC capacitors that are electrically acceptible they all have blade style quick connect terminals. Conversely, it looks like screw terminals are the standard on DC capacitors.

Does anyone know of an AC capacitor in this range that has screw terminals?

Also, out of curiosity, what does the designation of Motor start/run capacitor mean with respect to the electrical properties? I am familiar with using AC capacitors for starting single phase motors, but I am wondering if it has some sort of electrical or spec meaning? Does it perhaps relate to the fact that AC current will flow through them continuously?

 

[itsmoked]

Can't say on the spade screws, my friend, but the start/run is all about intermittent and continuous, so you have that right.

That is interesting. Now that I think about it I have never seen an AC cap with screws... They do all seem to have spades.

What, are you some kind of screw snob?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[MacGyverS2000]

For $100 I'll put holes in the spade terminals for you

Dan - Owner

http://www.Hi-TecDesigns.com

 

[Noway2]

(Drawls) A

http://wwwwwl'right...

The idea is that there will be about 15 of these per machine: 3 phase with 5 caps in parallel on each phase. The thought was to run a set of bus bars instead of trying to wire to each one of these caps to make the assembly easier.

Any thoughts as to how this might be accomplished easilly?

 

[ScottyUK]

What about power factor correction caps?

Check out

http://www.icar.it/

for some examples. I haven't used their PFC caps but the power electronic types are decent enough. They have a mix of blade and stud types.



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If we learn from our mistakes I'm getting a great education!

 

[itsmoked]

Use a piece of circuit board with these on them:

http://www.keyelco.com/pdfs/p32.pdf

The 3528.

While you're at it add a fuse/cap so when one blows the others can stay on-line.

Don't forget about cap swelling and heat dissipation.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Noway2]

Thank you to both Itsmoked and Scotty.

We had a project meeting today and the boss said that he wants the blades soldered to the caps (yuck). We think he is concerned about the quick-fits comming off.

I am still investigating the capacitors and will keep the PFC caps in mind, though these don't seem to be as common of a category.... The problem at this stage is still more mechanical design than anything else at this point.

I spoke with the mech engineer and she is going to try and come up with a concept on monday using the quick fits. Then we will see what the boss thinks.

 

[ScottyUK]

With soldering I'd be more concerned that the cap is damaged by the heat because they likely aren't designed for a high temperature process like soldering. If the reliability of Fastons was so bad would they be so popular with the automotive industry? Sure, you can buy poor quality ones but the types from (e.g.) AMP and T&B are pretty good. Make sure you get the right one to fit the blade on the cap - there are different standard blade thicknesses available.

PFC caps are common enough but because they're used by the electrical, as opposed to electronic, industry they're just not usually listed by electronics suppliers. If you Google [blue]power factor correction capacitor[/blue] for wherever you located are I expect you'll get some good leads.


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If we learn from our mistakes I'm getting a great education!

 

[Noway2]

Scotty,

My employer would be please to hear that T&B makes good connectors, hint hint.

I finally got a hold of Aerovox yesterday and they said that yes that they sell exactly what we are after under the name of power factor correction caps and agreed that you will have difficulty finding them through electronics suppliers.

Just wanted to say that you had an excellent suggestion there. Thank you.

 

[ScottyUK]

No problem at all, glad it helped.

I should have also said: buy a decent crimp tool for the decent quality Fastons. I am pretty sure that most of the problems with Fastons are caused by crappy crimp tools distorting the shape of the lug so it doesn't mate properly with the capacitor (or whatever) and overheats. I know that T&B and AMP tooling prices are extortionate and through their pricing policy they create an environment where third party vendors thrive, but be careful when choosing an aftermarket crimp tool. There are a few really good ones but they are vastly outnumbered by the bad ones.


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If we learn from our mistakes I'm getting a great education!