True Double feed (-48v)

[Amnon]

Hi,
I would like to supply my company communication box with two power
connectors that will allow the -48v feed of the box.
I intend to use two serial diodes in order to OR the two "hot" -48v traces
into one trace.

Should I use another set of diodes (in the reverse direction off course) to
OR the two "neutral" -48v_Return traces as well , or can I short them both
on my PCB right after the connectors ?

A short will fit my needs better for several reasons but sometime ago I was
told that a standard (NEBS?) requires a "True double feed" which he
interperted as a set of diodes for the RETURN traces as well.

Can anyone tell me if he was correct, and if so to which standard he refer
to, or there is no problem to OR only the "hot" traces?

Any comment will be appreciated?

THX

Amnon

 

[jan]

"Amnon" <amnon_po@bezeqint.net> wrote in message news:<40bea9b1@news.bezeqint.net>...

Hi,
I would like to supply my company communication box with two power
connectors that will allow the -48v feed of the box.
I intend to use two serial diodes in order to OR the two "hot" -48v traces
into one trace.

Should I use another set of diodes (in the reverse direction off course) to
OR the two "neutral" -48v_Return traces as well , or can I short them both
on my PCB right after the connectors ?

A short will fit my needs better for several reasons but sometime ago I was
told that a standard (NEBS?) requires a "True double feed" which he
interperted as a set of diodes for the RETURN traces as well.

Can anyone tell me if he was correct, and if so to which standard he refer
to, or there is no problem to OR only the "hot" traces?

Any comment will be appreciated?

THX

Amnon

////

Hi Amnon,

I see you didn't an answer to your problem either.
Looks like we have to find a smarter NG. Let me know if you do.

Jan

 

[Amnon]

Jan,
I am afraid I didn't fully understand your comment (NG ?)...
However, if you are intersted in this issue as well I have received from a
compliance lab the recommendation number in NEBS which describes the
suggested way to attend this issue , and they do recommend diodes on both
the -48V and the 48V_RTN.
In case you are intersted I can deliver this paper to you.
Amnon

"jan" <janan@695online.com> wrote in message
news:9a619ffc.0406061742.59d2f046@posting.google.com...

"Amnon" <amnon_po@bezeqint.net> wrote in message
news:<40bea9b1@news.bezeqint.net>...
Hi,
I would like to supply my company communication box with two power
connectors that will allow the -48v feed of the box.
I intend to use two serial diodes in order to OR the two "hot" -48v
traces
into one trace.

Should I use another set of diodes (in the reverse direction off course)
to
OR the two "neutral" -48v_Return traces as well , or can I short them
both
on my PCB right after the connectors ?

A short will fit my needs better for several reasons but sometime ago I
was
told that a standard (NEBS?) requires a "True double feed" which he
interperted as a set of diodes for the RETURN traces as well.

Can anyone tell me if he was correct, and if so to which standard he
refer
to, or there is no problem to OR only the "hot" traces?

Any comment will be appreciated?

THX

Amnon

////

Hi Amnon,

I see you didn't an answer to your problem either.
Looks like we have to find a smarter NG. Let me know if you do.

Jan