Spellman -40kV PTV power supply

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Spellman -40kV PTV power supply

Post by Andrew Seltzman »

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)?

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Re: Spellman -40kV PTV power supply

Post by Doug Coulter »

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 »

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 »

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 »

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
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Spellman High Voltage Electronics
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Re: Spellman -40kV PTV power supply

Post by Richard Hull »

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 »

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 »

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 »

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
631-630-3110
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

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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Re: Spellman -40kV PTV power supply

Post by Richard Hull »

I am unsure of your HV connector. I have several Spellman supplies that I picked up at hamfests. The ones I have have what looks like a PL259 uhf type threaded barrel with no guts in it sticking out of the back. I have cobbled up my own cable with large diameter, heavy, yellow, 50kv, silicone auto ignition wire, (copper core). I solder a naked banana male end, (barrel removed0, to the silcone cable. I next get a piece of plexiglass or lexan tube about 12-inches long and thread the silcone wire and banana plug through it. Note: the tube must, obviously, slide smoothly into the PL259 opening.

Epoxy the banana plug such that only the point of the plug extends from the end of the plexiglass. No need for a shielded cable here as long as you are mindful not to touch or move the silicone wire while the supply is on. Note: the plexiglass tube must extend about 3" outside of the back of the unit for insulation purposes.

Hope this helps and is the type plug you have on your device.

Richard Hull
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Re: Spellman -40kV PTV power supply

Post by Cliff S »

Regarding Andrew’s Q’s:
One schematic is dedicated to the X2094, the single PWB, open air HV type construction. (See title block). The other is the Control PWB for the generic PTV series, the potted HV section with the 2-PWB construction. The inverter sections (half-bridge FET’s) are basically the same. The HV in the potted section is a half-wave CW, with feedback R’s and stuff like that.

350W is OK for continuous operation, with some air cooling. 600W is pushing it. Maybe OK for some low duty, maybe 1 minute ON, 10 minutes OFF. But don’t yell at me if you pop those diodes.

Not sure why you would be getting OVP faults. But it’s possible. Really hard to say about any post filter. Probably not a concern on stability. If in doubt, just put a large R in series. As large as you can allow. Make sure it can handle the 40kV impulse, and the power.

On the HV connector: That model has an LGH 4I style. Google it. Good luck. It may be tough to find. Let me know if you hit a dead end.

On Rich’s comments on the HV connector: I think maybe this is a general comment, and yes, Rich, you have it deciphered. See attached as an example of a typical cable construction. This however is NOT the cable that would mate to Andrews unit, it’s just an example of how one type may look. Andrew’s connector will not support 40kV reliably unmated, and without the proper mate. LGH styles rely on a compression fit, forcing our air. Generally called “cone” type connectors because of the cone taper shape.

Best Regards,
Cliff Scapellati
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

Does anyone have a table with the jumper functions?

The LGH-4i connector is hard to find, no-one stocks it as a standard component, they are all made to order and cost several hundred per unit. It would be easy to male a matching connector if I could find the metal nut for the connector, it is a 1-14 thread. Does anyone know a good source for a cap / compression nut with this thread?

Andrew
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

I decided to make my own connectors. The nuts are made by turning down a 1-14 brass jam nut, and silver soldering (w/ kester 2222 flux) a washer onto the top. The washer is partially recessed into the nut face for proper centering(nut was turned down on a 1-14 precision arbor to center the threads on the lathe axis) and the soldered area was then filed down so there is a seamless transition between the nut and the washer. The threads on the nut were smoothed with purple scotchbrite so they don't damage the plastic LGHI thread on the connector.

The brass hex nuts are:
http://www.ebay.com/itm/360415477101?ss ... 1497.l2649

The washers are:
McMaster P/N 92916A420

The HV plug will probably be made out of PEEK, and will be held into the connector with the nut.

Andrew
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Re: Spellman -40kV PTV power supply

Post by mircado »

Cliff S wrote: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
631-630-3110
Dear Cliff Scapellati ,
thank you for your services
if you please i need the schematic for spell man PTV5N350
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Re: Spellman -40kV PTV power supply

Post by mircado »

i have T3 burnt in PTV5N350
what can causes this and what can i do and what is alternative
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Re: Spellman -40kV PTV power supply

Post by Richard Hull »

An image of T3 would be nice. It could be a death spiral for the rig or an easy fix. No pix, no suggestions.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
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Re: Spellman -40kV PTV power supply

Post by Dennis P Brown »

Interesting series of posts; I too have one of these 40 kV, 5 ma units (with the proper HV cable/connector rated to 50 kV.) So, just adding forced air cooling along with a low input fusor resistance allows a higher current draw to be safely handle by the unit? Of course, a proper ballast resistor must be included in line with the fusor.
So, would 10 -12 ma then be a workable safe limit?

Also, Mr. Couter, concerning this part of your post
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)
I have a 50 kV 0.2 uF cap. Exactly what does that buy me if I place it on the output side of my Spellman unit for continuous operation (besides instant death if I make a mistake ... )? I thought that adding a cap in that part of the circuit only helps with output ripple and nothing else (assuming this isn't a reference to a pulsed system; then the usefulness of the cap for increased current is obvious.)
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

Finally got around to modifying the spellman supply, I am now well versed in how the spellman feedback control circuitry works.

Modification of power supply successful, system now operating at 9mA output. The modification involved changing the voltage input on pin 10 of U7 (LF444ACN) from 5V to 9V. My version of the supply has a non-standard current feedback calibration of 1V/mA rather then 10v=100%(5mA) so the gain of the MAFBK op-amps did not have to change. This brings the current limit to 9mA instead of 5mA, the previous limit for the 200W version.

The transformer secondary does start to get hot as viewed on a thermal imager, next modification is to add an internal blower to blow air over the winding.

The OVP problem was caused by the power supply being designed to take a 0-4v input for 0-40kV output, rather then the 0-10v for 0-100%(40kV). When connected to the 10V reference the input potentiometer was trying to tell the supply to go over 40kV and tripping the OVP circuit.
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

Also, the HV cable that I built for the LGH-4i connector. An o-ring(not shown) fits on the barrel and is compressed against the fitting when tightened
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Re: Spellman -40kV PTV power supply

Post by Richard Hull »

Very, very nice work Andrew. This shows "where there is a will, there is a way"! Onward and upward.

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

Annotated schematic with modifications:
spellman-annotated-schematic.pdf
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

As advised by Cliff, I have added a blower to keep the HV transformer secondary cool. It is a 12v blower and is fairly high performance generating significant airflow over the winding. The power supply is designed for a 24v fan so a DC-DC converter is used to convert the voltage to 12v.

12v DC blower
SAM_4446a.jpg
Standoff added to power supply
SAM_4447a.jpg
12v DC blower mounted on standoff and aimed over transformer winding, DC buck converter converts 30V from supply to 12V for the fan
SAM_4448a.jpg
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

Drawing power from the 24V port was found to cause a voltage spike of shutdown(even though this is where fan power was supposed to come from). Instead an AC-DC power brick was connected to the internal corecom inlet filter to supply power to the fan, solving the HV spike problem
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Re: Spellman -40kV PTV power supply

Post by Garrett Young »

Another question for Cliff ...

Is there any headroom on the voltage multiplier section? Can the PTV30N be run at 31 or 32 output kV with feedback modification?
- Garrett
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