Re: DC Voltage of three phase rectifier greater?

On Feb 22, 1:17 pm, Ignoramus13847 <ignoramus13...@NOSPAM.
13847.invalid> wrote:
On 2009-02-22, Wes <clu...@xxxxxxxxx> wrote:



RangersSuck <rangerss...@xxxxxxxxx> wrote:

On Feb 21, 8:36?pm, RangersSuck <rangerss...@xxxxxxxxx> wrote:
On Feb 21, 12:33?am, Ignoramus19266 <ignoramus19...@NOSPAM.

19266.invalid> wrote:
I did a very extensive investigation of this. I opened this drive and
basically took it apart, board by board (while keeping notes as to
what is plugged to what).

What I found out is that there is a separate (from DC bus) phase loss
detection circuit. At least that is what I think.

The three wires connected to L1, L2, and L3 directly, are connected to
a tiny separate three phase rectifier (made of six little diodes), and
the output of that rectifier is fed into another board. There is no
capacitor at all in this circuit. I cannot think of any purpose of
this circuit, other than phase loss detection.

Therefore, simplistically, it would seem that adding a little
capacitor to this circuit may stabilize voltage there and fool the
board into thinking that all three phases are present.

Any thoughts on this?

i

If this is true, that there's no filtering on the output of this
rectifier, you would see 360Hz ripple from it. It's entirely possible
that the ripple frequency is monitored. Take a look at the input
circuit on the next board. Chances are that there is a voltage divider
that brings the voltage down to something like 5 volts. If that's the
case, maybe you could disconnect this rectifier and replace it with a
360Hz oscillator. That would cost something less than $0.50. Or, if
this is going into the input of a missing pulse detector, maybe you
could just fake the output of the detector.

HTH

Yikes - I just realized that Iggy, who blocks posts from Google
Groups, will never see this. I really don't have the time or
inclination to change news readers right now (I've been down that road
before - I ran a major usenet feed in the early 90s), so if someone
wanted to forward this to Iggy...

Done

I unblocked RangersSuck, it is not that I block GG because I do not
like it, only because spammers post through it. Thanks a lot for a
good thinking on this measuring question.

--
   Due to extreme spam originating from Google Groups, and their inattention
      to spammers, I and many others block all articles originating
       from Google Groups. If you want your postings to be seen by
         more readers you will need to find a different means of
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Understood. (and thanks, Wes). Getting a better new reader is
somewhere on my list of things to do, but Google Groups is just so
damned convenient.

Anyway, I'd be real interested in hearing how this missing phase
detector works out.
RS
.

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