[time-nuts] Transformer inrush current and transformer simulation
dk4xp at arcor.de
Wed Jun 8 03:54:23 EDT 2016
Am 08.06.2016 um 02:31 schrieb Mike Monett:
> I was not interested in examining the frequency response, saturation
> effect or core losses. These are only important after the core goes
> into saturation.
> I was only interested in the result of switching at the peak or at
> the zero crossing. This is clearly defined at the beginning of the
> The saturation and core losses are outside the scope of the
> investigation. The investigation was only to examine the effect of
> switching at the peak or at the zero crossing. This was clearly
> stated at the beginning of the paper.
> My analysis correctly defined an unloaded transformer as the only
> case where switching at the peak or the zero crossing made any
> difference. This was the goal, and it was met.
Saturation is not outside the scope. It is the very heart of the problem.
You need to build up a voltage opposite to the grid voltage to keep the
That requires an inductance and that requires a core that can be magnetized.
If the core is already magnetized to the limit from a previous session,
it is as good
as simply not there at all. What remains is some meters of copper wire
appreciable L and that is not enough.
I'm haunted by that effect myself on a regular base in that I have a fat
class A Krell
audio amplifier and it pops the fuse of my living room once in about 5
switching it on.
> I also showed that very few solid state switches were available that
> switched at the peak, that most vendors simply supply devices that
> switch at the zero crossing and state to get a model that will
> accept the surge currents, that switching at the peak could cause
> severe surge currents with capacitive loads,
Nobody uses large transformers anymore, everybody has a diode bridge ,
and a DC/DC behind it. Then zero voltage switching makes sense.
> and that I could not
> find any reference that stated switching at the peak would not cause
> core saturation.
I provided references that zero voltage switching leads to saturation,
and so did others.
> Your comments offer no additional information regarding the
> advisability of switching at the peak or the zero crossing. The
> information you do supply is irrelevant to the problem, and mostly
> irrelevant to LTspice.
you are right. This is not a LTspice problem but your modelling problem.
> Attila Kinali
>> It is upon moral qualities that a society is ultimately founded.
>> All the prosperity and technological sophistication in the world
>> is of no use without that foundation.
>> You need to consider getting new sigs. The two you post have little
>> or nothing to do with timenuts, and I'm sure everyone has them
>> memorized by now.
OMG , I'm not Attila, but I may need a special time nuts .sig!
Es ist schon alles gesagt worden, aber noch nicht von jedem. (Valentin)
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