5 to 10kV rated gate transformers

On a sunny day (Fri, 02 Jun 2017 11:02:43 -0700) it happened John Larkin wrote in :

This one can zap too:

Still working after those years...

Right. The transformer(s) will be tossed. Any such tests have to be only "design" tests.

True.

I totally agree. I'm just looking for something we can use in our lab that doesn't cost too much for 140 pieces, and won't be failing all the time.

I used to have to replace 10kV-rated KiloVolt $150 reed relays running at 6kV, every 6 months. So I have a healthy respect for those horrible gradual potting failures.

A friend had modified an old vacuum cleaner for the degassing.

After brewing some Belgian beers I am almost convinced that some of the more potent Belgian yeasts could also do that job. They eat anything that gets in their way.

Yeah but you grew up in New Orleans where most people spoke English back then and it has a waring in English :-)

Most, except folks like my English teacher from New Orleanse who grew up speaking French. So whe was also a French teacher at our school.

When I was a teenager I made capacitors out of dual-sided copperclad FR4 and used them in an amplifier where they were exposed to 5kV. The reason was purely budgetary since there was no way I'd ever touch my beer budget for that. I now know (back then didn't) that it wasn't kosher but they held up for years. Unlike a commercial ceramic cap which violently blew and turned most of its white ceramic into bubbly green glass.

Hint to readers: Don't do this!

The Louisiana cajuns mostly spoke cajun French until WWII, when they were drafted into the army and taught English. They still have a distinct accent and use a lot of their own words.

At least one can still understand some of it, they don't speak super fast like many Mexicans do.

Where I could not understand one word was on an oil rig on the North Sea. One of the guys I worked with was a Scot who had to or rather was forced to learn English at age 6 when school started for him. Before that he only spoke Gaelic as did all of his friends and neighbors. When he found another guy on the rig who grew up Gaelic I couldn't understand anything. Sounded like this:

Yes, but interesting idea, I like it. Epoxy.

Eww!

What kind of power-coupling did you get?

"flat rod-type" what does that mean? I couldn't find available ferrite shapes for the HV design concepts I played with. "bar and frame" sounded good, but I couldn't find inventory given that CCFL went out of flavor. Not even on Alibaba.

Ok. What sort of potting are you using, I remember the resin they used was a polyurethan compound (from Axson) which is quite dangerous to handle and degassing could occur during polymerization ... I've always consider those HV components suspicious.

Be careful Win ! Habib

It can be quite high. The key is the word "resonated" that John mentioned. You have to scale down to your coil size:

Thing is, resonant won't likely work if you want to pulse a gate.

Maybe you can find some stuff for experiments here:

Win's lab:

:-)

You can also just make the winding do an ugly hairpin around the via, so that it can clear the other layer's winding. Doesn't screw up leakage too badly.

Tim

That works. It's hard to draw and adds a little leakage inductance. But you don't want the via to be close to the winding on the other side, which gets ugly at kilovolts of clearance.

It's been a while. It was probably some 10s of milliwatts.

I used a roughly 1" long dumb-bell sort of ferrite core, basically a rod with bulges on both ends. That gave fairly good mag coupling between parallel antennas.

I did this for Niagra Mohawk, who wanted to install these meters all over India. In India, some good fraction of the power is stolen, so we had some anti-tamper features in the meter, to detect bypassing and such. It never got to production.

The split pot core thing should have good coupling. I like the surface-mount drum cores on opposite sides, all surface-mount with no wires or glue, but the magtetic path would have a lot of air gap as compared to the pot core halves. Might work, though.

The trash near the inflamed desk on which "ON" is written and the two guys not so impressed ... i suspect this was not the first shot ... next time it will be the building itself going to blow !

Winfield keep calm and gentle ;-)

Habib

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I once worked as a trainee for a company that developed 1MW UPS supplies. A senior engineer was often smoking with a pipe in his mouth. He came by, an d looked into a 220kW converter and right there an IGBT blew, making a VERY load noise. Amazingly he didn't twitch, or loose the pipe. The coolest eng ineer I ever met

Cheers

Klaus

That looks a bit like like my high-school chemistry class, probably zinc and sulphur reacting. the teacher knew how much to use to get the flames up to the ceiling.

After epoxy potting, the capacitance increased to 3 pF. Next, prolonged HV insulation tests. Within the epoxy potting, there's about 2 mm** clearance to the core and 5 mm coil-to-coil. External wiring creepage distance is 17 mm. Typical material specs range from 12 to 20kV/mm, or 24kV min for 2mm. Maybe I'll test at 15kV. (The maximum it'll ever encounter in my +/-5kV bipolar switch is 5kV dc for a few hours.)

Win,

Did you notice Digikey has your part status marked "obsolete"?

I'm working on a pulser too. Mine's 10MHz, lower voltage (V = 0 to +/-1kV), transitions under 10nS, and I'm deciding between stacks of silicon FETs or pairs of the Cree/Wolfspeed C2M SiC FETs.

A drawback of the usual FET stacks is that I have to turn 'off' quickly too.

Since I only need 1kV, I find this MuRata dc-dc converter interesting as a potential power supply for the isolated gate drive...

It uses a pcb transformer, it's surface-mount, 4.2kV-rated, and Ciso = 2.5pF.

Cheers, James Arthur

Maybe find out who distributes these, they do custom: