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Re: Current peak from MMC (fwd)





---------- Forwarded message ----------
Date: Thu, 15 Apr 1999 08:54:49 +0300
From: Marco Denicolai <Marco.Denicolai-at-tellabs.fi>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Current peak from MMC






Tesla List <tesla-at-pupman-dot-com> on 14.04.99 01:47:01

To:   tesla-at-pupman-dot-com
cc:    (bcc: Marco Denicolai/MARTIS)
Subject:  Re: Current peak from MMC



>Original Poster: Finn Hammer <f-hammer-at-post5.tele.dk>

>Tesla List skrev:
>>
>> Original Poster: "Marco Denicolai" <Marco.Denicolai-at-tellabs.fi>
>>
>> Hi Finn.
>>
>> If you look at the MKP 375 characteristics, don't forget to have a look
>to the
>> CAPACITANCE:
>>
>> a MKP 375 rated for 2 kV has got 30000 V/us  dV/dT but only in models up to
>> 2700
>> pF (yes, pF!). Models up to 0.01 uF have got dV/dT = 10000 V/us and models
>> up to
>> 0.022 uF drop down to 6700 V/us.

>Marco, I don`t know where you get your numbers from,

>From the Philips original datasheet, of course.

>but if you read my
>post carefully, you will see, that the dU/dT values change, according in
>fact with the envelope size of the cap.

Certainly, but the size affects the CAPACITY they can put inside. As a matter of
fact, a higher capacity needs a bigger size that, in turn, reduces the dU/dT
available. This is not a rule, it is simply how the MKP 375 is specified by Mr.
Philips!
You got to look to the right component, exactly to it, to find its ratings.

>>In the specksheets that I downloaded from Philips, the 375 is rated at
>>3300 V/µS for the big envelope with 27 mm Pitch, and 5000V/µS for the
>>envelope with 22,5 mm pitch.

Again, this is true for the 1000V devices (see datasheet 1998 Mar 04 p.12). If
you look at p.20 you find the 2000V devices with 10000 V/us for the 22.5 mm
pitch and 6700 V/us for the 27.5 mm pitch.

>>
>> The MMKP 376 (which is MY CHOICE)  rated for 2kV is available with all
>> values up
>> to 0.033 uF and for ALL values Philips ensures a dV/dT > 10000 V/us.

>Oh! the lovely 376, I was only put off by the pricing in the Farnell
>catalogue. But yesterday I called Philips, and asked them to suggest a
>wholesaler, so that I could get a better price, and BINGO: They sell
>376ès at the same price as the 375 : 0,022µF -at-1600 V for 1/2 dollar, so
>I ordered 600 of them <SNIP>

Get a good tin bobbin and Happy Welding! :)