P
Paul E. Schoen
- Jan 1, 1970
- 0
Robert Baer said:Where did the trannie get the sex change?
A Massive Prong was removed, forming the hole in the donut.
Paul
Robert Baer said:Where did the trannie get the sex change?
Paul E. Schoen said:The Wiki says otherwise. And I have had a lot of experience with high power
toroids and have seen the effects of high inrush current.
http://en.wikipedia.org/wiki/Inrush_current
I have personally observed this in our circuit breaker test sets. We take
care to apply voltage at about 70 degrees phase angle to obtain an initial
current peak equal to those that follow, and adjust the timing so that
there are equal numbers of positive and negative half-cycles. Inrush
current on successive pulses is minimal. But if there is an unequal number,
and a net DC component, there is always a much higher peak inrush current.
This is easily seen with short duration pulses of several cycles. In
breaker testing, of course, the breaker may trip at any time, sometimes
causing net DC, and the next operation usually exhibits high inrush.
Some other references:
http://relays.tycoelectronics.com/appnotes/app_pdfs/13c3206.pdf
http://powerelectronics.com/mag/power_magnetic_solutions_solving/
http://www.melcontransformers.info/images/transformer.pdf
Paul
"Phil Allison"
The Wiki says otherwise.
I have personally observed this in our circuit breaker test sets.
Can a toroidal former become permanently magnetised and cause excessive
current draw ?
N_Cook said:Can a toroidal former become permanently magnetised and cause excessive
current draw. ? One, in front of me from an amp, drawing excess current ,
does not attract a small piece of iron. I don't know what the main
secondaries are supposed to provide, but can give 300 watts into 4 ohms.
I've wound off the primaries (yes external to the secondaries) to try and
understand what is going on with this transfornmer. Applying 70 volt ac ,
from a variac, across series secondaries is ok but increase to 75 volt
and
the current draw goes up to 1/4 amp. Should be able to take twice that
voltage. Absolutely no visible problem , to the wiring or the coating of
the
toroid and both secondaries measure DMM the same DC. Tomorrow will apply
something a bit over 70 volt with temperature sensitive labels fitted
around. I will even try a TV degaussing coil.
I don't know what the main
secondaries are supposed to provide, but can give 300 watts into 4 ohms.
I've wound off the primaries (yes external to the secondaries) to try and
understand what is going on with this transformer. Applying 70 volt ac ,
from a variac, across series secondaries is ok but increase to 75 volt and
the current draw goes up to 1/4 amp.
Should be able to take twice that voltage.
Tomorrow will apply
something a bit over 70 volt with temperature sensitive labels fitted
around. I will even try a TV degaussing coil.
While it gives good background on PCBs it does not inform on the
regulatory situation. Moreover some of the background is missing,
like the presence of PCBs in varnishes and potting compounds used for
ballasts and transformers. Also regulation wise very nearly all uses
of PCBs are now banned.
John said:
Phil said:"Paul E. Schoen"
** Not true of any normal commercial toroidal sold for use with AC supply,
JosephKK said:It ain't necessarily so.
Start with this for current US regulation:
http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&tpl=/ecfrbrowse/Title40/40cfr761_main_02.tpl
Paul E. Schoen said:It would also be helpful to know how the toroid was mounted, and if the
failure occurred where pressure was applied. Toroids are usually mounted
either flat with washers and rubber gaskets with a single screw through the
hole, or vertically in an "Omega" bracket, with some rubber cushioning
material around the periphery. But in either case there may be additional
pressure on a "high spot" where two windings may be crossed, and softening
of the insulation from overheating may also contribute to a short.
Paul E. Schoen said:A Massive Prong was removed, forming the hole in the donut.
N_Cook said:Can a toroidal former become permanently magnetised and cause excessive
current draw. ?
Phil said:"N_Kook"
** So the amp's DC rails are about +/- 53 volts.
Means the tranny likely has two secondaries, each of 38 volts.
** Spot on.
** Absolute, fucking BOLLOCKS !!
Wot moronic math is this anencephalic pommy turdbrain using ?
** Fuckwit morons like YOU should be locked up for the safety of the
public.
Depends on the working flux Phil. If one had been designed for very low
radiated field, it's entirely possible that effect would occur.
Phil said:"Eeyore"
** Utter bollocks.
The sharpness of the saturation knee is NOT a function of AC primary
voltage.
JosephKK said:No thanks, i already did that work twice for my cow-orkers. It was
not worth it, they did not learn a darn thing. Twice burned by others
whose job was to keep up with this stuff.
Eeyore said:It's a function of working flux density. A transformer designed for low
radiated
field might be operating at a much lower working flux than a standard
commercial
type, hence it would take much more magnetising force i.e. primary volts
before
saturation. Simple physics.
It's a function of working flux density.