RE: Re: Capacitor Selection

["Hawes,Timothy Edward (GEG)" <haweste@xxxxxxx>]

David,

These were some of the ones on my list http://www.maplin.co.uk/ part # DT72=
P (also some from CPC but the catalogue is at home :-(  )

Which states: Leakage current: 0.01CV or 4=B5A whichever is larger (>3
mins=
)

Therefore leakage current is 4=B5A, or (2200 * 25) * 0.01 =3D 550 =B5A, so
=
leakage current is 550=B5A ? (did I do my sums right ?)

To give a bit more background - I'm replacing capacitors in an existing
pie=
ce of kit (dielectric has leaked out) so I didn't want to deviate too much
=
>from
oked at seem to have very similar specs and with your comment re: leakage
c=
urrent, I'm much reassured :-)

And yes, caps are right next to a big-ish heat sink !

Thanks for the comments and the URL,

Tim H.

-----Original Message-----
From: David Buckley

--- In ukha_d@xxxxxxx, "Hawes,Timothy Edward (GEG)"=20
<haweste@a...> wrote:
> Hi all,
>=20
> I'm need to buy a couple of radial capacitors but am unsure as to=20
what some of the specs mean. I know I need a 25V, 2200=B5F unit but=20
what about leakage current ?

My opinions:

These sound like power supply caps, so leakage current is almost=20
irrelevant.  But for a cap of 2200uF, I'd have thought that 4ua=20
would be a hard to achieve value.

Heat kills electrolytics, and designers (including me) always put=20
them next to things that get hot.  Thus a higher temp rated one is=20
good.  The same is not true of voltage with electrolytics; try not=20
to go too OTT.  Thats hard (but less important) with little caps=20
(10uF often are 63v rated and used on 5v) but with biggies try to be=20
over but not by more than a factor of a couple of times.

But to put everyone out of their misery, see some typical cap specs=20
at http://www.uei.com.tw/prodlist/lsh.html








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