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DRSSTC project From Italy

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JoeBonanno

Thu Jan 15 2015, 04:33PM

Registered Member #14660 Joined: Mon Apr 22 2013, 04:05PM
Location: Sicily, Italy
Posts: 19

Hi to all

some small news in building up my DR.

the bridge was finished, the U.D. 2.5 tuned and installed inside a metal enclosure.

here some wave form with phase lead added!

Wave

down here one medium power test, 670A 170V on bus, without secondary coil. This is gate signal, not bridge Output.

about the spike on the red signal, we supposed to be noise......or.....we hope to be! but, till now, it work great.

Wave 2

Now it's time to build up primary and secondary coils.

I choice the following parameter for secondary:

Diameter 250mm
Height 1000mm
wire 0.45mm
approximate resonant freq 1/4 wave 43khz
approximate impedance of resonant system 80k (about)

for primary, i have some questions and doubts:

the idea was to build a conical primary with 40Â° angle, about 8 turns of 12mm diameter copper pipe.

but, yesterday i saw the new design of primary from ArcAttack and Ward. The toroidal style one! It look amazing.

the idea was to test this king of design, but i'm scared about coupling. You know that i always build spark gap tesla coil that don't like to much coupling, is't the same with DRSSTC or i can rise it making a conical or toroidal primary?

this is the most important doubt that i have, i hope that someone can help me and explain the theory about it!

thanks
Joe

Graham Armitage

Thu Jan 15 2015, 06:52PM

Registered Member #6038 Joined: Mon Aug 06 2012, 11:31AM
Location: Salado, TX
Posts: 248

Joe, in the Wave2 photo - is the red trace the bridge output? I am guessing the yellow one is a feedback CT correct?

JoeBonanno

Thu Jan 15 2015, 07:10PM

Registered Member #14660 Joined: Mon Apr 22 2013, 04:05PM
Location: Sicily, Italy
Posts: 19

in all two photos the red trace is one gate of low side IGBT, the yellow one is a feedback TC that i use for current monitoring, 1:1000 with 12R burden resistor!if i have time, this week i will check the bridge output. i find a isolation transformer for line input for clean the noise coming from 230V line.

JoeBonanno

Mon Jan 19 2015, 04:11PM

Registered Member #14660 Joined: Mon Apr 22 2013, 04:05PM
Location: Sicily, Italy
Posts: 19

Today, while make some testing of the bridge, playing some midi and have fun heating some metal inside the primary, i decided to push the system up to 1kA at 230V for see if it's stable. My Current Transformer loaded with 10R resistor give out 20Vpp. I can earn the sound of vibration of a iron plate inside the primary and see the light of laboratory lo down...very down!! but, i notice that the OC protection do not trigger! strange! i tried to rise up to 1.1kA for a second....but nothing happened! so i open the driver box and start to turn down the trimmer and after few turns the OC start to trigger instantaneously when i rise a bit the duty, less than 100A! and nothing change if i turn back the previously position! so, what happened? maybe comparator failure? is boring but i need to disassembly the driver box for find the issue!

Wolfram

Mon Jan 19 2015, 04:49PM

Registered Member #33 Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971

Make sure that your OCD setpoint voltage is within the common mode input range of the comparator. If the OCD comparator is an LM311 running from 5V, the setpoint should be somewhere between 1.2 V and 3.5 V for the comparator to work correctly. Decrease the current transformer burden resistor if needed.

JoeBonanno

Tue Jan 20 2015, 08:31AM

Registered Member #14660 Joined: Mon Apr 22 2013, 04:05PM
Location: Sicily, Italy
Posts: 19

Found the problem. for some unknown reason the trimmer remain hold at low position!

JoeBonanno

Thu Jan 29 2015, 11:14AM

Registered Member #14660 Joined: Mon Apr 22 2013, 04:05PM
Location: Sicily, Italy
Posts: 19

Some update! After have fixed the driver OCD i started to build up the secondary coil.

1050mm hight x 250mm diameter, 0.45 wire ( 41in x 9.8in AWG 25.8)

here some pictures of secondary, enclosure and JacaTC table!

other images!

JoeBonanno

Wed Feb 04 2015, 05:21PM

Registered Member #14660 Joined: Mon Apr 22 2013, 04:05PM
Location: Sicily, Italy
Posts: 19

some painting and final assembling!

i choose Powercon for 600V supply and standard computer connector for 230V auxiliary.

two HP big fan, one push air on the MMC and the other one, directly on IGBT heatsink push out. This two are able to create an awesome flux of air inside the cabinet!

As a discharge protection i will install a relay that which bus capacitor on a big resistor when i unplug power and stay hold until next uses!

photos

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