Howdy Hank,

Thanks for the follow-up! Perhaps they used a voltage regulating
transformer. I think some of the telcom rectifiers used them.
I know some mainframe computers did.

It's still a curiosity to me. Though I've seen enough occult
behavior from wound magnetic devices that I wouldn't discount it,
I'm tempted to wonder if there's another variable that was
coincident with the welded laminations.

73



"Henry Kolesnik" wrote in
:

Grumpy
Years ago in 93 or so on a Telco fiber system by Alcatel we took severe
hits when the air conditioner came on and it was traced to the station
rectifier. The Gould rectifiers had a weld bead and when we replaced
them another make which I can't recall that didn't have weld beads the
problem went away. Its quite strange since the rectifiers floated big
batteries but a vco in system was sensitive to the spike. After doing
some research I found an explanation that I can't recall because I was
too busy with other problems and mine had gone away. Alcatel spent
several hundred thousand trying to find the problem and I stumbled on to
it by shear luck.

73
Hank WD5JFR

Hey Grump
A transformer is one of the simplest electrical machines and pretty well
understood in the classical design but when some of the parameters are
changed we don't have much experience or investigation and probably
wont. Hot swappable rectifier modules have made transformer based
rectifiers uneconomical kinda like carburetors and fuel injection. If
you have the time, check with some of the old time designers of
transformer rectifiers. Let me now what you find out. I had some notes
but those are long gone.
Hank
"Grumpy The Mule" wrote in message
...
Howdy Hank,

Thanks for the follow-up! Perhaps they used a voltage regulating
transformer. I think some of the telcom rectifiers used them.
I know some mainframe computers did.

It's still a curiosity to me. Though I've seen enough occult
behavior from wound magnetic devices that I wouldn't discount it,
I'm tempted to wonder if there's another variable that was
coincident with the welded laminations.

73



"Henry Kolesnik" wrote in
:

Grumpy
Years ago in 93 or so on a Telco fiber system by Alcatel we took
severe
hits when the air conditioner came on and it was traced to the
station
rectifier. The Gould rectifiers had a weld bead and when we replaced
them another make which I can't recall that didn't have weld beads
the
problem went away. Its quite strange since the rectifiers floated
big
batteries but a vco in system was sensitive to the spike. After
doing
some research I found an explanation that I can't recall because I
was
too busy with other problems and mine had gone away. Alcatel spent
several hundred thousand trying to find the problem and I stumbled on
to
it by shear luck.

73
Hank WD5JFR

I left out switch based hot swappable
"Henry Kolesnik" wrote in message
...
Hey Grump
A transformer is one of the simplest electrical machines and pretty
well understood in the classical design but when some of the
parameters are changed we don't have much experience or investigation
and probably wont. Hot swappable rectifier modules have made
transformer based rectifiers uneconomical kinda like carburetors and
fuel injection. If you have the time, check with some of the old time
designers of transformer rectifiers. Let me now what you find out. I
had some notes but those are long gone.
Hank
"Grumpy The Mule" wrote in message
...
Howdy Hank,

Thanks for the follow-up! Perhaps they used a voltage regulating
transformer. I think some of the telcom rectifiers used them.
I know some mainframe computers did.

It's still a curiosity to me. Though I've seen enough occult
behavior from wound magnetic devices that I wouldn't discount it,
I'm tempted to wonder if there's another variable that was
coincident with the welded laminations.

73



"Henry Kolesnik" wrote in
:

Grumpy
Years ago in 93 or so on a Telco fiber system by Alcatel we took
severe
hits when the air conditioner came on and it was traced to the
station
rectifier. The Gould rectifiers had a weld bead and when we
replaced
them another make which I can't recall that didn't have weld beads
the
problem went away. Its quite strange since the rectifiers floated
big
batteries but a vco in system was sensitive to the spike. After
doing
some research I found an explanation that I can't recall because I
was
too busy with other problems and mine had gone away. Alcatel spent
several hundred thousand trying to find the problem and I stumbled
on to
it by shear luck.

73
Hank WD5JFR

Howdy Hank,

I've been designing switch mode magnetics for about
thirty years now. The more I learn the less I know.
It's true that the principles are well known but the
implementation is a morass of compromises. At the
power level many of my designs operate at, second
and third order effects can suddenly become serious
and unexpected design complications. Some people
enjoy puzzles. I guess that's why I like designing
this sort of stuff.

I've worked on a lot of weird stuff, big cap charging
supplies, pulse compressors, very high voltage or high
current, and tiny stuff with extremely low noise outputs.
But I don't have much experience with line frequency
magnetics beyond EMI filters. As you say there's
not much call for it now. But unfettered by
all the weak components the big iron can support
amazing overloads, so I think there's still a place
for it. At least for now. The cost of steel and
copper (and the transportation costs) for such heavy
beasts is certainly making them increasingly less
attractive.

Lately I've been working on equipment in the 10KW-60KW
output range switching at 75KHz range. The whole system
weighs much less than just the line frequency transformer
that would be required alone.

The only big iron guys I know are now retired or dead.
And the companies I've dealt with that make that stuff
tend to have very little engineering staff, not much new
going on, (other than some efficiency improvements from
amorphous cores) they just crank out the product in cook
book fashion. I think nuances of it may soon be a lost.


73


"Henry Kolesnik" wrote in
:

Hey Grump
A transformer is one of the simplest electrical machines and pretty well
understood in the classical design but when some of the parameters are
changed we don't have much experience or investigation and probably
wont. Hot swappable rectifier modules have made transformer based
rectifiers uneconomical kinda like carburetors and fuel injection. If
you have the time, check with some of the old time designers of
transformer rectifiers. Let me now what you find out. I had some notes
but those are long gone.
Hank

hey all:

A good trick for the lams is clear nail polish as you reassemble them.
Just a quick wipe, as it'll spread as you squeeze in the last few
lams
under a "Quick-Grip" clamp.

I could go to the nail shop get a peddicure and coat my lams at the
same time. A great idea if only I could handle the fumes.


Varnish is the best thing. Warm the varnish and the
transformer first before you dunk it. That will reduce
the viscosity and improve penetration. A little thinner
in the pot may help too.

I lucky I can stand the effects of epoxy but no way varnish. For nail
polish or varnish I gots to gits me a up or down draft venilator
exhastt system.

If you have bolts thru the lams have you torqued them to the point of
twisting them off? If you haven't you might want to loosen then and
add
some more varnish to the lams while they're loose and then torque
them

Thanks I retorqued them and that reduced the noise by 6db. Now I have
a less effecient buzzer

Bolts through the laminations should have insulators
(usually fiber board washers) under the heads. Just
one end will do, there's no need for them under the
nuts. But shoulder washers are best so the bolts don't
short any laminations together deeper into the core.

Good idea I seen many a transformer that had fiber spacers over the
whole length of the bolt plus fiber washers..


put the
transformer into the box, and fill the box up with enough sand that
you
have 1-2 inches all around the transformer, and that might muffle the
buzz. You'll need to worry about heat dissipation through that sand
which
will act like an insulator, but if you are on the air only a couple
of
hours per day,

I likes this one, but I gots alot of kittie litter that comes from
some place in Arkansas, it is mostly quartz and some other trace
minerals.

The only big iron guys I know are now retired or dead.
And the companies I've dealt with that make that stuff
tend to have very little engineering staff, not much new
going on, (other than some efficiency improvements from
amorphous cores) they just crank out the product in cook
book fashion. I think nuances of it may soon be a lost.

Yes lams are going the way of the dinosuars. Maybe that's why they
cost so much looky the price of a good audio output transformer for a
tube audio amplifier and they go up to at least 20Khz.

Your other option is to figure out some clamping arrangement so that
the
laminations are held close and tight.

Yes I think I will put together a vise of sorts. Custom made to fit
the transformer.

73 and thanks for all the good information.

n8zu

The only big iron guys I know are now retired or dead.
And the companies I've dealt with that make that stuff
tend to have very little engineering staff, not much new
going on, (other than some efficiency improvements from
amorphous cores) they just crank out the product in cook
book fashion. I think nuances of it may soon be a lost.

Yes lams are going the way of the dinosuars. Maybe that's why they
cost so much looky the price of a good audio output transformer for a
tube audio amplifier and they go up to at least 20Khz.

Your other option is to figure out some clamping arrangement so that
the
laminations are held close and tight.

Yes I think I will put together a vise of sorts. Custom made to fit
the transformer.
==============
Followed this thread with great interest .
Reason : I have an Astron RS-50A , 13.8V -50 Amperes unit for 220V-AC
input which is buzzing heavily. Upon switch-on the group circuit breaker
in the house sometimes trips due to the high switch-on current surge .
This can be overcome by adding a soft start circuit which initially puts
a say 25 Ohms-50Watts resistor in series with the primary transformer
winding ,shorting this resistor after a second or so.

However I fear that the main reason for the buzzing is that the
transformer (of US origin) was designed for 60 Hz ,whereas here in the
UK (like in all European countries ) the supply frequency is 50 Hz.
Can someone on this NG please confirm/reject my suspicion.

Another possible reason could be that the cabinet sheet metal which is
very close to the transformer is vibrating (transducer effect) .


TIA for any constructive advice/opinion

Frank GM0CSZ / KN6WH

On Oct 29, 8:21*am, Highland Ham wrote:
The only big iron guys I know are now retired or dead.
And the companies I've dealt with that make that stuff
tend to have very little engineering staff, not much new
going on, (other than some efficiency improvements from
amorphous cores) they just crank out the product in cook
book fashion. I think nuances of it may soon be a lost.

Yes lams are going the way of the dinosuars. Maybe that's why they
cost so much looky the price of a good audio output transformer for a
tube audio amplifier and they go up to at least 20Khz.

Your other option is to figure out some clamping arrangement so that
the
laminations are held close and tight.

Yes I think I will put together a vise of sorts. Custom made to fit
the transformer.

==============
Followed this thread with great interest *.
Reason : I have an Astron RS-50A *, 13.8V -50 Amperes *unit *for 220V-AC
input which is buzzing heavily. Upon switch-on the group circuit breaker
in the house sometimes trips due to the high switch-on current surge .
This can be overcome by adding a soft start circuit which initially puts
a say 25 Ohms-50Watts resistor in series with the primary transformer
winding ,shorting this resistor after a second or so.

However I fear that the main reason for the buzzing is that the
transformer (of US origin) was designed for 60 Hz ,whereas here in the
UK (like in all European countries ) the supply frequency is 50 Hz.
Can someone on this NG please confirm/reject my suspicion.

Another possible reason could be that the cabinet sheet metal which is
very close to the transformer is vibrating (transducer effect) .

TIA for any constructive advice/opinion

Frank * * GM0CSZ / KN6WH- Hide quoted text -

- Show quoted text -

Frank I emailed XXXXXXX's address to you. He designed the Astron Power
supply.


Jimmie

However I fear that the main reason for the buzzing is that the
transformer (of US origin) was designed for 60 Hz ,whereas here in the
UK (like in all European countries ) the supply frequency is 50 Hz.
Can someone on this NG please confirm/reject my suspicion.

I suspect that you are right.

If I recall correctly, transformers designed for 60 Hz can suffer from
excessive quiescent current flow in the primary windings, if used on
50 Hz... the windings don't have enough inductance. Also, because the
frequency is lower, the transformer will be drawing more current
during the brief intervals (100 times per second) when the power
supply rectifiers are conducting and recharging the filter
capacitors... the abrupt changes in the current flow and the resulting
magnetic-field changes may be causing the windings or laminations to
move around and buzz.

Transformers designed for 50 Hz service generally work OK on 60 Hz...
it an "easier" job for them.

Transformers can also buzz if there's anything on the same mains
circuit which is generating harmonic currents (e.g. other linear power
supplies). Toroidal tranformers can be prone to buzz or hum if other
loads on the mains line are drawing current from the line in an
asymmetrical fashion and thus creating a DC offset on the mains... the
toroid goes into saturation.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Do you have GloBar resistors in the UK? These are high cold and go lo
with current. they used to be very popular in TVs over here.

--
Thanks & 73
Hank WD5JFR
"Highland Ham" wrote in message
...
The only big iron guys I know are now retired or dead.
And the companies I've dealt with that make that stuff
tend to have very little engineering staff, not much new
going on, (other than some efficiency improvements from
amorphous cores) they just crank out the product in cook
book fashion. I think nuances of it may soon be a lost.

Yes lams are going the way of the dinosuars. Maybe that's why they
cost so much looky the price of a good audio output transformer for a
tube audio amplifier and they go up to at least 20Khz.

Your other option is to figure out some clamping arrangement so that
the
laminations are held close and tight.

Yes I think I will put together a vise of sorts. Custom made to fit
the transformer.
==============
Followed this thread with great interest .
Reason : I have an Astron RS-50A , 13.8V -50 Amperes unit for
220V-AC input which is buzzing heavily. Upon switch-on the group
circuit breaker in the house sometimes trips due to the high switch-on
current surge . This can be overcome by adding a soft start circuit
which initially puts a say 25 Ohms-50Watts resistor in series with the
primary transformer winding ,shorting this resistor after a second or
so.

However I fear that the main reason for the buzzing is that the
transformer (of US origin) was designed for 60 Hz ,whereas here in the
UK (like in all European countries ) the supply frequency is 50 Hz.
Can someone on this NG please confirm/reject my suspicion.

Another possible reason could be that the cabinet sheet metal which is
very close to the transformer is vibrating (transducer effect) .


TIA for any constructive advice/opinion

Frank GM0CSZ / KN6WH

On Oct 29, 4:43*pm, "Henry Kolesnik"
wrote:
Do you have GloBar resistors in the UK? *These are high cold and go lo
with current. *they used to be very popular in TVs over here.

--
Thanks & 73
Hank WD5JFR"Highland Ham" wrote in message

...



The only big iron guys I know are now retired or dead.
And the companies I've dealt with that make that stuff
tend to have very little engineering staff, not much new
going on, (other than some efficiency improvements from
amorphous cores) they just crank out the product in cook
book fashion. I think nuances of it may soon be a lost.

Yes lams are going the way of the dinosuars. Maybe that's why they
cost so much looky the price of a good audio output transformer for a
tube audio amplifier and they go up to at least 20Khz.

Your other option is to figure out some clamping arrangement so that
the
laminations are held close and tight.

Yes I think I will put together a vise of sorts. Custom made to fit
the transformer.
==============
Followed this thread with great interest *.
Reason : I have an Astron RS-50A *, 13.8V -50 Amperes *unit *for
220V-AC input which is buzzing heavily. Upon switch-on the group
circuit breaker in the house sometimes trips due to the high switch-on
current surge . This can be overcome by adding a soft start circuit
which initially puts a say 25 Ohms-50Watts resistor in series with the
primary transformer winding ,shorting this resistor after a second or
so.

However I fear that the main reason for the buzzing is that the
transformer (of US origin) was designed for 60 Hz ,whereas here in the
UK (like in all European countries ) the supply frequency is 50 Hz.
Can someone on this NG please confirm/reject my suspicion.

Another possible reason could be that the cabinet sheet metal which is
very close to the transformer is vibrating (transducer effect) .

TIA for any constructive advice/opinion

Frank * * GM0CSZ / KN6WH- Hide quoted text -

- Show quoted text -

I think some of the PC power supplies have a surge suppresor in them.
I you have some old power supplies around you coulld be in business.



Jimmie