High voltage Capacitor

Sorry did not mention the inductance values in my last post

L1 = 50uH L2 = 50uH

can not change the inductor values .

jess

Check Cornell-Dubilier:

Another good source may be Johanson. The standard value is 47nF. If it has to be precise you need special narrow tolerance caps and piece it together.

--
Regards, Joerg

http://www.analogconsultants.com/

Try AVX

Cheers

df

Dear Jess, You seem to be suffering from severe units confusion. My suggestion is to write down the equations you are trying to solve. Put in units everywhere. Then you may have to convert, to whatever the piece of test gear uses. But you will know what every thing means.

George H.

Hi,

I am using a series resonant LC circuit. The diagram of the circuit is given below

Voltage across L1 = 450 V peak to peak Voltage across L2 = 450 V peak to peak Frequency = 75KHz Current = 19A peak to peak Capacitor = 45nF

I am looking for a capacitor that can handle atleast 1000V peak tp peak , ideally more than 1000V peak to peak more than 19A peak to peak of current.

Thanks jess

While I was at Semco (Capacitors), everything was rated under DC voltage.

Mica caps were actually tested at double of the specified handling voltage printed on the package. It does not mean you should be using it in an application that way.

In AC applications, the applied RMS*1.414 = the DC rating of the cap as packaged.

You may want to be careful with the selection of caps these days, not to many do actual hi-pot testing well exceeding the advertised package ratings.

The 1kv cap you found should cover your needs, even when your circuit runs wild..

P.S.

You may want to pay close attention to ESR and tempco on the cap when it heats up. It is possible the inductor you have may compensate enough for the change as it too, heats up.

Jamie

But then where does your 26A rms come from? The capacitor you picked cannot handle 26A rms.

--
Regards, Joerg

http://www.analogconsultants.com/

Hi,

How much rms current it can handle? The data sheet says 15A peak. So, it means it can handle 30A peak to peak.

jess

15A peak would mean 10.6A rms. But in the datasheet it does not say that the currents are peak values, only "maximum". So it is possible that this means maximum rms current. It is best if you contact them about it.

--
Regards, Joerg

http://www.analogconsultants.com/

Typically, the peak value is a transient value only, the continuous / RMS value being some 20 times lower, depending. Would you run 12A RMS through a

26AWG wire? I certainly hope not.

Fortunately, capacitors for RF service, like the 290 series you found, are rated for RMS, continuous duty.

Unfortunately, you'll never find those caps for sale, at least at any reasonable price.

If you're still looking in the CDE catalog, 935 and 940C are their workhorse 'snubber' caps, stocked well by every distributor. Though rated for moderate RMS current, the larger values don't tolerate pulses and high frequency AC as well as one would hope (I haven't burned any, but I've heated some up in the process).

In general, look for polypropylene film capacitors; a few box style types in parallel will handle that current easily.

For high voltage and moderate current in small values (nanofarads), I might suggest PPB series capacitors from Illinois Capacitor, available from Allied Electronics. I've ran twice the rated current at high frequency (400kHz) through a set of PPBs and found them to survive well (capacitors that withstand high power at frequencies over 100kHz are uncommon and usually expensive).

PPBs are more expensive than Epcos, Panasonic, etc. brand caps, which are cheaper, but you get exactly what they're rated for.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

"Jessica Shaw"  wrote in message 
news:edd4833a-e4ff-4a57-97db-27e222a4637f@k6g2000vbz.googlegroups.com...
> Hi,
>
> How much rms current it can handle? The data sheet says 15A peak. So,
> it means it can handle 30A peak to peak.
>
> jess

--
http://www.deantechnology.com/pg_catalog/catalog_hvdcc.aspx

One of the top dogs in the game.

"Mycelium" wrote in message news: snipped-for-privacy@4ax.com...

They make a good product, but it?s a little pricey. Murata is a better bet on price.

Cheers

You obviously did not understand what was said.

Murata and Philips both make good HV cap products, but these guys would be the guys to go to for a mil spec design or a hi-rel design.

Now, the real question is: Just what did that remark tell you?

Because if you are unaware of the level of engineering, testing, and manufacturing involved with such products, then your statement, which is based SIMPLY and only on price, does not have enough information points to be valid.

Sure cheaper is easy to find, but since the OP wanted hi reliability and to push things at or near their limits, I would pay the extra few cents per device. It isn't always about price, and almost assuredly is never only about price. And with HV caps, it does matter because you can't tell if they are fried unless you energize them at full potential.