Dc pulse applied to Power transformer.

Homework?

I don't know. If I tell you that I'm going to whack a tree with a hammer, but I don't tell you how big the hammer is or how often I whack the tree, can you tell me what's going to happen?

Aside from that little problem, if the DC pulses are evenly spaced then there will be back emf and current harmonics. In both cases. If you apply DC pulses to just about any passive electronic component (and a transformer with a shorted secondary counts) then there will be back emf and current harmonics.

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400us, isn't going to give you much of an effect how ever, the 50 msec will. The pulse duration needs to be on long enough to generate some current which is going to create a magnetic field. If the source of this pulse does not have a sink on it, when turned off, you'll get some interesting results. :)

It's the collapsing of the field at a uncontrolled rate that generates this marvelous energy.

If you want some more details on this, you can find some documentation on the net about magnetic amplifiers.

This link may interest you. It talks about effects when shorting a winding on the transformer and things you can do with saturated xformers.

Jamie

If it's really a PULSE, there are current harmonics into just about any load. The only way to not have harmonics is to start with a pure sinewave, or DC.

The transformer is likely to have series stray inductance, and that means your coupling to the (shorted) secondary is not perfect; there will be back emf. If you discount stray inductance, the back emf will be dominated by the resistance of the windings (the EXTERNAL part of the circuit may be a short, but the winding resistance remains).

At 500KVA, I don't think they'll be a lot of R in there :)

Jamie

Please post the entire problem as it was presented in your textbook. You've left out some information that is very significant.

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I'm never going to grow up.

You've omitted the most important part of the "Please do my homework for me" question, namely, what you're willing to pay the consultant you're willing to engage.

Good Luck! Rich

Do you typically keep 500kVA transformers laying around in your junk box to try this out?

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Mr.CRC
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Furthermore, a pulse is not DC. If you apply DC, you will create heat in the coils (windings) of that transformer (now best called a heater).

A friend of mine did, and he applied a HV pulse to the primary to drive a Cockroft-Walton multiplier that drove a linear accelerator; result was a unique 4MEV accelerator in a garage, 100 percent home brew. Lead ore loaded concrete blocks for shielding donated by Stanford University (they desperately wanted it to be removed). Accelerator pipe made from industrial fluorescent lights for longest possible sections, one inch wide aluminum sticky-back tape regularly spaced to give a linear drift section.

It must be a very low current one. We have 2MEV units at work and the vessel that contains the rectifiers are large enough to crawl in side when apart. They hold 90PSI of SF6 gas when closed up. Operate on a

100KHZ via pie xformer made from litz wire. Behind that is a 250 kW hot cathode tube armstrong type oscillator that can operate up to 15kVDC.

Adjusting the OSC voltage sets the accelerator voltage at the beam along with setting the filament current to adjust the process for concentration of electron beam.

Our systems can operate in the 60-80ma beam current range and considering the voltage behind that, it's a lot of power.

Your friends unit must be a electron beam accelerator other wise if proton type was used, it wouldn't be such a deal. well, at least not as much.

Jamie

Strictly electron beam; rather low pulsed current.