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problems.. keeps tripping the house power

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Herr Zapp

Wed Oct 14 2009, 01:14AM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

a:d -

You response triggered a few more questions; something seems odd here:

1. Are you ABSOLUTLEY sure the breaker you are tripping is marked 80A???

2. Where is the outlet that you are plugging your coil into physically located?

3. Are you powering the entire coil set-up from a single outlet, or do you have more than one "power cord" plugged in?

This all sounds a bit unusual, as any breaker rated at 80A should be the "main" breaker protecting the entire breaker panel. Each branch circuit (outlets in garage, kitchen, bedrooms, etc) should be protected by individual breakers with lower current ratings (like 13A). One of the smaller breakers (protecting the outlet you have the coil plugged into) should trip well before the main 80A breaker trips.

A possible explanation may be that your 80A breaker also incorporates a GFI or RCD function, and that your coil is permitting enough ground leakage current to trip the GFI/RCD. This seems more plausible that tripping an 80A breaker due to overcurrent.

Regards,
Herr Zapp

teravolt

Wed Oct 14 2009, 03:18AM

Registered Member #195 Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111

Hi audio:deviant you should be able to mesure the bridge with an ohm meter. I think that one or boath fets are dead. are you using DRSSTC III scematics? DRSSTC III have a current limiting adustment at R23 for tuning.

has lots of good stuff on DRSSTC III. I have been over doug86 tread "How close must primary & secondary resonances be? " on what I assume is your coil. I think that it is still out of tune. Your coil will eat fets with out some adjusment. Once your bridge is working, at a low voltage 30vac find out what the primary frequency is using your scope. The DRSSTC should oscillate without the secondary. If you can adjust the the taps (one or two turns) on your primary and find how much range of frequency you will have. Your secondary frequency should fall with in 10% above the primary. when you get streamers this will detune the secondary at about 1pf per ft. I have read hear that at a DRSSTC at lower power will put a genral a sized spark and the as power goes up sparks will start leaping out of the output.
I don't think it is the breaker in your house but if the bridge is good the breaker is bad or your coil draws a lot of current. I would think that your coil would not draw more than 10-15 Amps. This can be reduced by changing your inerupter duration and rep rate.
can you list some pictures of the electronics setup

Steve Conner

Wed Oct 14 2009, 09:48AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Herr Zapp wrote ...

A possible explanation may be that your 80A breaker also incorporates a GFI or RCD function, and that your coil is permitting enough ground leakage current to trip the GFI/RCD. This seems more plausible that tripping an 80A breaker due to overcurrent.

That's what I said too, but the guy didn't seem to notice or understand. Check your setup for earth leakage, and if you don't know what earth leakage is, now would be a good time to learn! Maybe the insulation in your GDT has broken down.

doctor electrons

Wed Oct 14 2009, 09:57PM

Registered Member #2390 Joined: Sat Sept 26 2009, 02:04PM
Location: Milwaukee Wisconsin
Posts: 381

audio:deviant wrote ...

well ive build to the spec of the eastern voltage research mini brute schematics but have a bigger mmc and single dc cap.

heres schematic to the mini brute system.

hope that helps

This may not be your issue but it is possible i guess! The first time i fried a pair of igbt's on my minibrute halfbridge, it damaged the two of the tvs's.
You may want to check them. They were not totally fried but at closer inspection the leads had been thinned out from overcurrent. A new pair of igbt's did not remedy the coil back to working again. Hope this helps!

Doug86

Mon Nov 09 2009, 02:38PM

Registered Member #2424 Joined: Tue Oct 06 2009, 08:02AM
Location:
Posts: 17

Hi all, late to the party as usual...

To complete this thread, it turned out that the transient voltage supressors had gone short. This has now happened a second tme while testing the coil to higher voltages (again around 200v on the variac. Remember, no doubler on this coil).

I'm not completely sure I undersand what the TVSs do so I'm going to do some reading. has anyone had a similar problem in the past?

Doug

Frosty90

Mon Nov 09 2009, 11:20PM

Registered Member #1617 Joined: Fri Aug 01 2008, 07:31AM
Location: Adelaide, South Australia
Posts: 139

it turned out that the transient voltage supressors had gone short

What actual TVS's are you using? What are their ratings? I've had 400volt ones (340volt supply) go short after a primary/secondary flashover, but under 'ususal' transients they should be abe to absorb them (to a point, as long as they dont overheat, or explode etc). The TVS I've seen have a standoff voltage rating, and a breakdown rating and a clamping voltage rating. You should make sure the TVSs you use have a standoff rating higher than the supply voltage, and a clamping voltage lower than the max voltage of your transistors. The breakdown voltage is where it begins to conduct 'significant' current. So on my coil, I have a 340v suplpy, and 600v IGBTs and I use 1.5ke400a TVSs, which have a V standoff of 342v, a (max) breakdown of 420v, and a clamping voltage of 548v. I think these numbers tend to vary between manufactures, even on devices with the same part number! (someone may know better here) So check the data sheet from the company that makes your TVSs.

Cheers,
Jesse

teravolt

Tue Nov 10 2009, 05:28AM

Registered Member #195 Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111

if you are blowing TVSs it is pausible that the fets are
turning off at the wrong time. like frosty90 said the tvs is supose to clamp any forward voltages accross
the fets when they turn off. when the fet turns off at the wrong time like 90deg of the signwave that is being propigated in the primary tramendus voltages can drop across the fets. A tesla that is out of tune or glitches in the electronics. generaly easterns circuits are solid. Is your high primary resonsnce fixed now and or did you get a ground strike when this happened?

Doug86

Tue Nov 10 2009, 05:28PM

Registered Member #2424 Joined: Tue Oct 06 2009, 08:02AM
Location:
Posts: 17

I think the TVSs may well be a little under rated for this coil, hopefully james will chirp in with the actual values. Yes, they blew during a ground strike the first time around (turned out to be IGBTs this time).

Ive replaced the IGBTs with fairchild H0531AB30N60A4Ds.

The coil looks like it's in pretty good tune now (no visible beating in the ring up with 2" or so left on the primary for a little detuning).

Its running well enough for james' imediate needs, and we can get 2-3 ft arcs with 150-160v in, so we're shifting our focus towards the modulator for a bit.

Many thanks to all :)

klugesmith

Tue Nov 10 2009, 09:15PM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

loveHV wrote ...
audio.deviant wrote ...
>> alright, why do you think it would work the first few times up to 200v and then stop?
i think its luck because i also had some breaker problems, sometimes it worked and sometimes the breaker trips.

Some experimenters might not know how slow circuit breakers may be (by design, with allowance for temperature and manufacturing variables). One reference says "A typical thermal breaker must trip within one hour at 140% of its rating".

Square-D model QO breakers, popular in US residential panels, have a typical trip time of
10 to 50 seconds at 2X the rated current.
1 to 3.5 seconds at 6X rated current
Less than 1 cycle at 25X rated current.
ref: figure 9 at

(note slightly different chart for each standard current rating).

is much shorter and gives a more technical review of fuse & circuit breaker mechanisms. Its current/time charts are generally similar to those in first link.

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