The question is is the lopsided waveform between ~A and ground an accurate representation of a winding connected across a?

across any two of the phases?

?

I was under the impression that the output was supposed to be symmetrical. That said it just an assumption, As I have not?dared put an oscilloscope on to the three phase to check. Or for that matter had access to the three phase either.

The file is in Files > TEMP >?3 Phase question > 3 phase query.asc

Any enlightenment and or help will be gratefully received. Thank you

Suusi M-B

开云体育

Suusi,

What is happening is the voltage across the primary is not 0 at time=0, so you have a huge primary current at time=0.? Due to the long time constant it takes a long time for the primary imbalance to settle out.? You can avoid this problem by specifying UIC is the transient command.? Check Skip Initial operating point solution in the .tran window.

Rick

The question is is the lopsided waveform between ~A and ground an
accurate representation of a winding connected across a?

across any two of the phases?

Thank you sawreyrw

That really solved that one. I am glad that it is a simple fix :)

Thank you John?

For confirming what I thought was correct. :)

Thank you?Jerry Lee Marcel

Suusi M-B

Thank you John?

John,

That current is correct.? It is due to the start up transient and the DC component will eventually go to 0.? Whether the magnetizing inductance is too low depends on the VA rating of the transformer.

Rick

That current is correct.? It is due to the start up transient and the
DC component will eventually go to 0.?

Whether the magnetizing inductance is too low depends on the VA rating
of the transformer.

Thank you John

The three phase is 36Vac 500Hz which really chucks a spanner in the transformer design. Doubly so as I have no component values to go on from the schematics and the descriptive text is in German. I'm just having some fun guestimating values and seeing what happens. with the values i used and a SCR instead of a thyratron.

The example circuit was the minimum needed to demonstrate the problem.

开云体育

?

In message , dated Thu, 19 Dec 2013,
sawreyrw@... writes:


>Whether the magnetizing inductance is too low depends on the VA rating
>of the transformer.

500 mA with no load is too much anyway, I think,

even if the full load current is 50 A.

Also, the primary r.m.s. voltage is 56.6 V, not 62.3 V.

Still, never mind, eh?

--
OOO - Own Opinions Only. With best wishes. See
Nondum ex silvis sumus
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

开云体育

?

Thank you John

The three phase is 36Vac 500Hz

which really chucks a spanner in the transformer design.

Doubly so as I have no component values to go on from the schematics and the descriptive text is in German. I'm just having some fun guestimating values and seeing what happens. with the values i used and a SCR instead of a thyratron.

The example circuit was the minimum needed to demonstrate the problem.

The three phase is 36Vac 500Hz which really chucks a spanner in the transformer design.

开云体育

smalcolmbrown@... writes:

>The three phase is 36Vac 500Hz which really chucks a spanner in the
>transformer design.

The main issue is to get the thin laminations you need for 500 Hz. I
suppose they are available, as used in aircraft transformers, but maybe
really difficult to get in small quantities.

-- 

AC2CL 

I do not think there is any thrill that 
can go through the human heart like that felt by the inventor as 
he sees some creation of the brain unfolding to success... 
Such emotions make a man forget food, sleep, friends, love, everything. 

- Nikola Tesla 

 

Thanks interesting

I know that you can use a considerably smaller core at 500 Hz and less windings per volt. This is where the weight savings occur for avionics use.

I I have thought about the use of a switched mode, mainly for valve amplifiers, but wonder about the extremes of generating 800V DC at high frequency. I have not seen high speed rectifiers with greater than a 100 V rating. I guess that they exist, but the price tag is prolly horrendous and or the supply limited to defence contractors only.

The circuit I'm playing with, dates from WW2. It discharges 0.7 Joules in 2uS every 20mS (350Kw) into a 24:1 step up transformer… Yes 10kV pulses… Everything about this circuit is extreme.

Best regards

Suusi M-B

开云体育

I I have thought about the use of a switched mode, mainly for valve amplifiers, but wonder about the extremes of generating 800V DC at high frequency. I have not seen high speed rectifiers with greater than a 100 V rating. I guess that they exist, but the price tag is prolly horrendous and or the supply limited to defence contractors only.

The circuit I'm playing with, dates from WW2. It discharges 0.7 Joules in 2uS every 20mS (350Kw) into a 24:1 step up transformer… Yes 10kV pulses… Everything about this circuit is extreme.

-- 

AC2CL 

I do not think there is any thrill that 
can go through the human heart like that felt by the inventor as 
he sees some creation of the brain unfolding to success... 
Such emotions make a man forget food, sleep, friends, love, everything. 

- Nikola Tesla 

 

Yes it is a FuG 200 Radar set. I like reverse engineering things to see how they work. I understand PPI its the other approaches that I find interesting.

a stack of 1N4148's shudder a large stack then. Ta for the Idea. I think I got as far as 5?Schottky

?power devices and gave up.

Damn Yahoo still is not letting me have POP3 access to my email and the interface still doesn't like html emails :( It has been a week and a half since this happened and they still have not replied to my complaint :(

Merry Yule to all

Suusi M-B

Use UF4007(SF4007), they are 1A, 1000V, 75nS Trr and cheap. 1n4148 have only 75volt reveres voltage.

10pcs. in series gives 10KV. I would use 11 to have som margen.

开云体育

开云体育