[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: THOR: SMPS warmup behaviour followup



Original poster: "Kennan C Herrick by way of Terry Fritz <twftesla-at-uswest-dot-net>" <kcha1-at-juno-dot-com>



On Mon, 18 Dec 2000 08:00:19 -0700 "Tesla list" <tesla-at-pupman-dot-com>
writes:
> Original poster: "Marco Denicolai by way of Terry Fritz 
> <twftesla-at-uswest-dot-net>" <Marco.Denicolai-at-tellabs.fi>
> 
> Hello all.
> 
> Maybe some of you recall that over a month ago I had a problem with 
> Thor
> and its
> SMPS. 

[snipped]

> 2. The performance is still getting lower after some 15-20 seconds!
> 
> I have now identified what I believe is the actual cause: there is 
> some corona
> between the SMPS transformer secondaries and the ferrite cores. As 
> the corona
> grows together with charging voltage it is a good explanation for 
> the charging
> profile bending. I can also "ear" the corona. A week ago I had also 
> a discharge
> through the secondary (SMPS, not TC) coil former and the core, 
> resulting in one
> of the driver getting damaged.
> 
> I am now going to try two remedies:
> 
> 1. ground the ferrite core: at the moment it is floating. This 
> should
> prevent it
> from collecting charge (if it does).

[snipped]

It might be better to connect the core to the potential of the inner
turns of the coil that is on it.  Then, insulate the core from everything
else surrounding it.

As to grinding...I have no experience with this, except I know the stuff
is brittle.  I'd think careful application of it against a grinding-wheel
might do the trick.  But getting it smooth all over would be tedious. 
All it takes is 1 sharp edge, of course, to continue to produce the
corona.

KCH
________________________________________________________________