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My first DRSSTC

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Danielle

Sat Jul 28 2007, 04:18AM

Registered Member #632 Joined: Mon Apr 09 2007, 01:09AM
Location:
Posts: 267

ok I think I am finished although I am only getting 5'7" at tops with ground arcs I had to short the current limiter to allow for this. I do believe it is good for some wimpy TO-247 30N60s

heres the vidio

I also get some good pics soon but my main question is why if I run it at lower BPS I get racing arcs pri to sec.

after 1min of run time at full power I checked the temp of everything and everything was cold except the IGBTs were slightly warm with no fans. I will also be experimenting with the tunning a bit more to increase performance.

thanks for all the help,

Daniel.

Steve Ward

Sat Jul 28 2007, 07:53AM

Registered Member #146 Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055

Wow man, i gotta say im impressed. You started out not knowing much at all about this stuff, and have built your first coil, which not only performs well, but has had relatively few failures! Not many can claim that.

Danielle

Sat Jul 28 2007, 07:30PM

Registered Member #632 Joined: Mon Apr 09 2007, 01:09AM
Location:
Posts: 267

my only question is how do I change the max over current limiting because I would want some form of limiting not when I get huge ground arcs for me to pop the breaker. is it the load resistor I change? also should I further de-cuple because I am still getting racing arcs at lower BPS.

Steve Ward

Sat Jul 28 2007, 07:44PM

Registered Member #146 Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055

Yes, if you have already maxed out the potentiometer setting on the OCD circuit, then you need to lower the value of the burden resistor across the output of the CT (maybe just parallel another resistor of the same value to cut the resistance in half).

And if you are still getting arcing between coils, then the only solution i know of is to further reduce the coupling. Either that or put the entire coil in a vat of transformer oil

Danielle

Sat Jul 28 2007, 08:06PM

Registered Member #632 Joined: Mon Apr 09 2007, 01:09AM
Location:
Posts: 267

thanks I reduced the burden and it is better but I caint get nearly as long as with out it I have 1.5ohms now and I also decoupled it so it is .5" lower than the top turn. I only want to know what is the lowest I should go on that resistor. also when I removed one of the wires going to the CT I saw arcing from 1 to the other terminals. I measured the current I had going into the coil when running it to get consistent grounding arcs and it was 14A 120V I dont know if this is right or if I have more tunning to do. The last thing is I will do some point to point arcs to see its real full potential because I believe it can reach +70". and my last comment is that everything was getting warm not hot but warm including the wires going from the variac and the copper tubing on the primary, that shows sines of extrema current being drawn but the IGBTs are doing well with 90W of heat dissipation on each of them they are now cold.

thanks again.

edit

I realized my variac allowed me to step it up to 140VAC so I will try that tonight. it is rated at 10A 140V if I am pulling 120V 14A should I not do this or is a variac rugged enough to handle this?

Dalus

Sat Jul 28 2007, 09:14PM

Registered Member #639 Joined: Wed Apr 11 2007, 09:09PM
Location: The Netherlands, Herkenbosch
Posts: 512

You can use the double of the rated amperage of your varaic for short periodes of time, just let it cool off before you run it again. But please make sure your coil can handle that it would be a shame to see it break. Do you have a movie of it running at high powers? Can't wait to see it.

Danielle

Sat Jul 28 2007, 09:21PM

Registered Member #632 Joined: Mon Apr 09 2007, 01:09AM
Location:
Posts: 267

I have a problem with the audio ill tell you all and see if you can figure it out when I run it at higher power levels I get the music stopping then starting almost stuttering so until I fix this I won't be playing 6ft music arcs. I will try again after decoupling it a bit more and being able to run it at highest puls with and lowest BPS with out pri-sec arcing.

I posted a vid of the non adio full power though and I will get some 70" arc pics tonight too.

thanks for the help and I should be able to get even longer arcs soon with 20more volts. I will be running it at 400V DC I think I will need to add more fans and run it off a 20A line.

edit

I tryed it out at 50% I caint see the arcs but I have -.25 coupling and it worked fairly well the over current hasn't tripped yet and the music plays well. I will need to make an investment in a new variac because it burned me after 5min of run time at 50%. My parents wont let me run it though for a bit so no more pics for a few days. I do have one last question that is how dificult would it be to build a 40+ A Solid state variac? I need one because I caint be spending $200 on a variac.

Dalus

Sun Jul 29 2007, 11:56AM

Registered Member #639 Joined: Wed Apr 11 2007, 09:09PM
Location: The Netherlands, Herkenbosch
Posts: 512

Maybe your over current detection is triggering, that could explain the stuttering.

Reaching

Sun Jul 29 2007, 01:51PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

As far as i know, there are a few shematics on solid state variacs on this board, which should perform very well. Steve conner build one and a board member used his shematic and simplified it, so it wont be that hard. So for myself, i never used a solid state variac in one of my drsstcs, so i dont know how reliable it is, compared to a usual variac/transformer.

Danielle

Sun Jul 29 2007, 08:35PM

Registered Member #632 Joined: Mon Apr 09 2007, 01:09AM
Location:
Posts: 267

ok I dont know what to do I just ran it at full power and lowest BPS and a huge arc over killed all the IGBTs. I dont know how to stop this but I can run it at higher BPS.

I just need some 30N60 ferchild samples.

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