Spellman -40kV PTV power supply

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Spellman -40kV PTV power supply

Post by Andrew Seltzman » Sun Jan 29, 2012 8:10 am

Cliff Scapellati are you still out there?

I have a spellman PTV40N200X2113 power supply (-40kV, 5mA, 200W) that I am working on integrating into my fusor.
http://www.rtftechnologies.org/physics/ ... -power.htm
There is also a 350W output model capable of 9mA output, with the only visible difference being an external forced air cooling fan.

Does anyone know if the 200W version can be increased in power output with the addition of forced air cooling and internal adjustments? The data sheet also mentioned a 600W pulse capability, any info on this?
Does anyone know the functions of the internal jumpers and potentiometers?

There appears to be a model of 300W +5kV power supply for sale by several different sellers:
http://www.ebay.com/itm/SPELLMAN-X2094- ... 2c57cb810f
Found some pics of the inside:
http://laserpointerforums.com/f39/fs-sp ... 40654.html

Is it possible to interchange parts between the series to get more output power(can I put my power supply parts in a case like this with forced air cooling to get more output power)?

Andrew Seltzman
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Re: Spellman -40kV PTV power supply

Post by Doug Coulter » Tue Jan 31, 2012 10:02 pm

I have a couple customs of this supply here, modified for 12.5 ma output and 4 volt control and feedback signals (no current input or reference is supplied in mine). The only difference I can see in the picture is the HV transformer - mine has pies in the windings, and uses IRF 540's as the output FETs. I use one to drive my secondary grid used as an ion source here. It doesn't make many neutrons, but does make a few. Even with a 100k ballast resistor, micro-arcs keep the supply voltage down at any gas pressure it will fire up at. Running too close to the 40kv rating also tends to get it shut down from overvoltage - so I've not solved all issues with these as a main fusor supply - but I must say, I've not managed to break one either with some pretty severe abuse.
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman » Wed Feb 01, 2012 7:50 am

Do you have any pictures of your power supply?
With the 12.5mA modification, is there a timeout on the duration of the 600W output pulse(electronic timer, thermal sensor, or just a specified duty cycle)?
I assume your supply is forced air cooled.

My power supply used H15NA50FI FETs
Vds=500V, Rds=0.4ohm, Id=9.3A

Are you sure your supply uses IRF540 FETs, they have ratings of
Vds=100V, Rds=0.070ohm, Id=30A
That would not withstand rectified line voltage. My supply has over 200V on the filter capacitors when plugged in.

I have been thinking of using a multi-stage LC filter, and isolation diodes(prevent current pulse from propagating back to the supply) to help with the micro-arc problem. I kept getting the over voltage shutdown problem when running them on my fusor, probably from noise from the micro arcs.

Andrew
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Re: Spellman -40kV PTV power supply

Post by Doug Coulter » Wed Feb 01, 2012 2:33 pm

Oops, Andrew - I mis-remembered the number and transposed. It was IRFP 450. Which is similar to the number you mentioned but with higher current capability of 14 amps@ 500v. These seem to pop up in almost every line-rectified bridge driver for HV I've ever seen - both spellman and glassman, as well as my own designs. There doesn't seem to be anything better out there for this if you need the FET speed - I bought a big tube of them for my own uses here.

Sorry about that.

I don't have pix, but I can tear one down and get some. It's going to look just like yours, except for the HV transformer. Mine is the same size, but uses pies on the secondary (I have several and they all vary a little - some are encapsulated in clear silicone for the HV winding). At the detail level you can get from a picture, all else is identical.

I don't have a schematic, but I've traced out the parts I needed to in order to make them work. It's pretty simple in there. Lm3525 to make the pwm and a bunch of opamps for monitoring current and voltage, more or less, and the usual support junk. No house secret marked parts or anything. You can get the manuals from spellman online, that's all I've got. Basically for these customs - all they did was choose some different resistor values in the current/voltage monitor and input stuff. As far as I can tell - I also have a stock one and that seems to be the only difference. They leave out some different parts depending on output polarity - that's chosen by what they stuff in the board and the CW stack.

Yup, we both see that shutdown issue. Even if you run one down near say 30kv, so that stops happening, the fact that even a pretty large ballast R can still draw nearly half an amp discharges the CW stack in there quick and it spends all its time charging it back up. Not sure what the best ballast design is going to be - things that make more kickback possible aren't going to help, but it's going to be the key to making these otherwise very nice supplies work well as main fusor power. That would be worth doing I think, they're otherwise very nice and compact and reliable. I've really abused mine, no failures.

It might take nothing more than using a larger cap across the supply output before the ballast impedance - but you'd need either a large inductance or something that would limit the micro arc current to lower levels and let it "go out", which a 100k ballast resistor alone doesn't manage to do.
(In fact, going to that from 50k only dropped the voltage under load - no other change was noted)

The ones I'm using are very inductive - 1" diameter 13" long, wirewounds. I've tried filling them with ferrite to increase that - no change in operation. They get good and warm too as the spellman puts out more than rated power while trying to re charge its own stack capacitors - they only measure delivered power - but not the stack discharge energy. So if you take it out in pulses like this, you can get a lot more than the nameplate ratings. I don't have a 40kv 1uf cap to try across the supply, which is about what it looks like it's going to need. Those are sort of scarce.

And no, no forced air - mine don't get hot at full load in current limit. Nice little design, very efficient.
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Re: Spellman -40kV PTV power supply

Post by Cliff S » Mon Feb 06, 2012 5:51 pm

Hi Gents,
Sorry for the late chime in.
200W vs. 350W PTV: Basically, same beast, just with some forced air cooling. HV XFRM is the limit for continuous power operation. If in doubt, just blow some air across the unit. For peak power near 600W, you may run out of steam. Run it at higher input V to get the most output power. “Steam” is generally limited by the primary side L. It’s the pot core inductor next to the HV XFMR. Take some turns off to get more inverter power, but only if you have to. (But not too many). To get the increase current out of the control/HV, you will need to lower the value of the I sense R. (You have a schematic to do that?). As always, be careful, and proceed at your own risk. These are clearly “voiding the warranty” types of changes

Best Regards,
Cliff Scapellati
Executive Vice President of Engineering
Spellman High Voltage Electronics
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Re: Spellman -40kV PTV power supply

Post by Richard Hull » Mon Feb 06, 2012 8:07 pm

Again, many thanks to Cliff for working with us on issues like this.

I feel we all regard him as am immense help and source of valuable info. on Spellman systems.

We always stress the significant hazards regarding working with HV gear. It is the one big area of fusion work that can kill or injure instantly. Safety within this effort is a high priority. I always advise that anyone who isn't rather electronically capable not to "fiddle" with the internal "guts" of any supply. If you do, you may screw something up or ruin a part that just might cost more than you paid for the whole supply surplus!

As far as warranty goes, I do not think we have more that one or two people who have the ready cash to buy new supplies of the Spellman class. Thus, 99% of any Spellmans discussed in these forums are certainly surplus or e-bay acquisitions where the warranty is long expired and, even if new enough, such warranty is not transferred with a change in ownership.

Richard Hull
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman » Fri Feb 10, 2012 2:27 pm

Hi Cliff,

Thanks for the info. Would you happen to have a schematic for the 40kv supply?

By higher inputV, I assume you mean switch the supply to 230V input. Is the HV transformer limited by volt-seconds or resistive heating of the secondary? Is there a maximum current limit for the multiplier (output ripple is not critical for fusor applications)? Would you have any ideas to prevent the supply from tripping the OVP circuit when there is a micro arc?

Doug,

I also managed to get a PTV5P300X2094 on ebay for $70 to use for comparison and testing some of the modifications. They appear virtually identical except for the 230v input voltage, HV transformer which has two secondary windings and the HV multiplier.

thanks,
Andrew
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Re: Spellman -40kV PTV power supply

Post by Doug Coulter » Fri Feb 10, 2012 4:20 pm

I wouldn't mind having the schematic for this one myself. I have 4 total (2 had the factory mod for 12.5 ma and 4v control voltages). They're really nice but would be even nicer tweaked for fusor use. These have to be the most size and weight and power efficient possible fusor supplies.
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Re: Spellman -40kV PTV power supply

Post by Cliff S » Mon Feb 13, 2012 5:05 pm

See attached.
The PTV series has many generations, and has many custom models. No claims made on how accurate attached doc is to your models.
Sorry, can't send some of the high kV schematics. Our policy is not to share that knowledge in such detail.

As always, any servicing of these units should only be made by qualified service personnel. Be careful.

Best Regards,
Cliff Scapellati
Executive Vice President of Engineering
Spellman High Voltage Electronics
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman » Mon Feb 13, 2012 5:39 pm

Cliff,

Thanks for the schematics, any information you can provide is greatly appreciated and will provide a good starting point. Are both PDFs are for the X2094 supply (5kV 60mA)?

As for the -40kV model, can you tell us if it is safe to run the system continuously at 350W or 600W with proper cooling? My main concern is burning out a diode or other component in the potted HV multiplier assembly where it would be difficult to repair. Would there be any issues(stability or other) placing an LC or RC filter in series with the supply output to prevent arc noise from tripping the OVP circuit?

I'm also having trouble finding a distributor for the mating HV connector on 40kV supply, do you have any recommendations?


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