0.5mm2 = 3A, 0.5mm2 = 10A

A

Andre Majorel

Guest
I'm shopping for wire to use with 0.156" Molex connectors and
I'm finding things which leave me perplexed. For instance,

Farnell ref. 140345 : Pro Power MC16/0.2 TYPE 2

Farnell ref. 584990 : Pro Power CBBR0156

Both are said to be 0.5mm2, 16/0.2mm. But while 140345 is rated
for 3A, 584990 is rated for 10A. WTF ?

The only difference I can see is that 140345 is tinned and
584990 is not. But how would not tinning allow 3.33 times as
much current ? Is there something I don't know about cables ?

Oh and the outer diameters differ too : 140345 is 1.6mm, 584990
is 2.6mm.

--
André Majorel <URL:http://www.teaser.fr/~amajorel/>
(Counterfeit: rosifohar@aerogene.com femovyh@rifle.com)
"La presse doit diffuser des idées saines." -- Serge Dassault,
propriétaire de la Socpresse.
 
"Andre Majorel" <cheney@halliburton.com> a écrit dans le message de
news:slrndhgtr3.3d6.cheney@atc5.vermine.org...
I'm shopping for wire to use with 0.156" Molex connectors and
I'm finding things which leave me perplexed. For instance,

Farnell ref. 140345 : Pro Power MC16/0.2 TYPE 2

Farnell ref. 584990 : Pro Power CBBR0156

Both are said to be 0.5mm2, 16/0.2mm. But while 140345 is rated
for 3A, 584990 is rated for 10A. WTF ?

The only difference I can see is that 140345 is tinned and
584990 is not. But how would not tinning allow 3.33 times as
much current ? Is there something I don't know about cables ?

Oh and the outer diameters differ too : 140345 is 1.6mm, 584990
is 2.6mm.
Click to expand...
André,

unless there's a typo (I didn't checked, so you should), what characterizes
the current capability of a wire is :
- its working temperature (may vary, depending on the insulation material
and the allowed ambiant temperature range)
- its dissipation capability.

The former is obvious and the latter depends on the insulation Rth and
diameter. While increasing the insulation diameter increases the conductive
heat resistance, it also increases the external convective surface, thus
diminishing the convection resistance. Both resistances are added and for a
given insulating material, there's an optimum external diameter.

Your 10A cable benefits probably from both points.


--
Thanks,
Fred.
 
On 2005-09-02, Fred Bartoli <fred._canxxxel_this_bartoli@RemoveThatAlso
_free.fr_AndThisToo> wrote:

"Andre Majorel" <cheney@halliburton.com> a écrit dans le message de
news:slrndhgtr3.3d6.cheney@atc5.vermine.org...
I'm shopping for wire to use with 0.156" Molex connectors and
I'm finding things which leave me perplexed. For instance,

Farnell ref. 140345 : Pro Power MC16/0.2 TYPE 2

Farnell ref. 584990 : Pro Power CBBR0156

Both are said to be 0.5mm2, 16/0.2mm. But while 140345 is rated
for 3A, 584990 is rated for 10A. WTF ?

The only difference I can see is that 140345 is tinned and
584990 is not. But how would not tinning allow 3.33 times as
much current ? Is there something I don't know about cables ?

Oh and the outer diameters differ too : 140345 is 1.6mm, 584990
is 2.6mm.

unless there's a typo (I didn't checked, so you should), what
characterizes the current capability of a wire is :
- its working temperature (may vary, depending on the insulation
material and the allowed ambiant temperature range)
- its dissipation capability.

The former is obvious and the latter depends on the insulation Rth and
diameter. While increasing the insulation diameter increases the
conductive heat resistance, it also increases the external convective
surface, thus diminishing the convection resistance. Both resistances
are added and for a given insulating material, there's an optimum
external diameter.

Your 10A cable benefits probably from both points.
Click to expand...
Interesting. In both cases, the insulation is PVC.

Thanks.

--
André Majorel <URL:http://www.teaser.fr/~amajorel/>
(Counterfeit: ovoz@wealthy.com gur@sewerage.com)
"La presse doit diffuser des idées saines." -- Serge Dassault,
propriétaire de la Socpresse.
 
Hello Andre,

Both are said to be 0.5mm2, 16/0.2mm. But while 140345 is rated
for 3A, 584990 is rated for 10A. WTF ?
Click to expand...
10amps over a 0.5sqmm wire would give me the goose pimples. I guess the
fire marshall wouldn't like that either. I remember that some times ago
the VDE requirement for short runs was 1.5sqmm for 16amps and many
people (including me) consider even that marginal.

Regards, Joerg

http://www.analogconsultants.com
 
Joerg schrieb:

Both are said to be 0.5mm2, 16/0.2mm. But while 140345 is rated
for 3A, 584990 is rated for 10A. WTF ?

10amps over a 0.5sqmm wire would give me the goose pimples. I guess the
fire marshall wouldn't like that either. I remember that some times ago
the VDE requirement for short runs was 1.5sqmm for 16amps and many
people (including me) consider even that marginal.
Click to expand...
Additionally, these specs might be related to different environmental
conditions, i.e. single straight wire vs. many (close) wires, different
ambient or wire temperature, etc. You'd have to check the detailed data
sheets from both manufacturers...

Besides that, in your application with the Molex connectors the current
handling capability does not only depend on the cable, but also on the
connector contact itself - which more often is the limiting factor.

--
Dipl.-Ing. Tilmann Reh
http://www.autometer.de - Elektronik nach Maß.
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top