| Nixie |
| I'm looking for schematics for a suitable switching power supply, 115 VAC mains in, 90 VDC 15 A out. Didn't want to do linear due to the need for huge transformer and filter caps. |
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| Tall Shadow |
Hey Nixie,
Are you replacing a damaged Plasma supply, or are you DIY'ing a Plasma cutter from scratch?
Tall Shadow |
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| Nixie |
| DIYing from scratch. I already built the torch head. |
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| Tall Shadow |
I'd love to get any info you could provide!
I've been searching for information about doing the same thing for some time now, and what little I did have was just lost on an un-backed up hard drive.(dumb!, dumb!, Dumb! Me!!)
Any plans, Sites, or other information would be helpful!
I've had so little luck in finding any information on the requirements needed by a Plasma cutter supply.
It might be that, the power supply could be made form a modified existing supply.....I don't know..
Thanks!, I'm really looking forward to seeing where this goes.
Tall Shadow |
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| Nixie |
Well I only have plans for the torch head. I bought them on eBay, and I don't think it would be fair to the seller if I gave them to others. At $7, it's not much to buy them.
A directly mains-rectified and filtered supply using a multi-gallon salt water resistor can be found at http://tech.groups.yahoo.com/group/...HomeBrewPlasma/
However, I'd prefer a more efficient switching supply. |
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| Nixie |
Oh come on, surely someone here knows about switching power supplies. Where do I find a 15 kVA high frequency transformer?
What about multiples of smaller transformers, like say several of this one in series: http://www.surplussales.com/Transfo...chingXmers.html (TP) 20T0175-A01 |
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| powerbecker |
Nice link!
Why not buy there 2 for 69$ each?
Input: 115 / 230v - 15 amps max. 50 / 60 / 400 Hz
Output: 48.0v @ 15.6 amps, 5.1v @ 50 amps, 24.0v @ 10 amps / 2000 watts total
Voltage adjustment: ± 10% minimum
Line & load regulation: 0.2% + 5mV max
Ripple: RMS 0.1% or 10mV
Ripple: Pk-Pk 1% or 50mV
Dynamic response: 25% load step, 2% or 100 mV (any output)
Recovery time: To within 1% in 300΅ sec
Overvoltage protection: 2 to 5 V 122% to 134% of output voltage; 12 to 48 V 110% to 120%; recycle AC.
Overload protection: 105% to 120% of rated current. Auxiliaries 105% - 140%
Short circuit protection: Protected for continuous short circuit, recovery automatic
Reverse voltage protection: 100% or rated output current
Thermal protection: Each module thermally protected. Input module: Auto recovery. Output modules: Recycle AC
Dimensions: 5" x 11-3/4" x 5"H |
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| Nixie |
| Can I put them in series to get the voltage I need? Plus, $138 for under 1.5 kW is steep, and where's the DIY in buying a complete unit. |
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| powerbecker |
Nixie:
"Can I put them in series to get the voltage I need? "
Don΄t know but normally the secondary is left floating.
"$138 for under 1.5 kW is steep"
That depends...I suppose to buy only the parts (plus the broken parts ;) )will cost about the same!
"and where's the DIY in buying a complete unit."
And why You look to surplus parts?
You don΄t consider to mix and press ferrites and so on....:D
Ok that can be a point, but in my view that is not a challenge in contrast eg to create a useful plasma speaker!
Heinz! |
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| Nixie |
| quote: | Originally posted by powerbecker
Don΄t know but normally the secondary is left floating. |
The main point of having a transformer in a plasma cutter supply is isolation from the mains, so that the + clamp connected to the work piece can be grounded, so that the operator is safe. Otherwise I could just directly rectify mains and have the workpiece live, so that I can kill myself.
| quote: | | That depends...I suppose to buy only the parts (plus the broken parts ;) )will cost about the same! |
I don't think your estimate is correct for a switching supply, thoug it would be if I went for a linear one, due to the need for a large transformer.
| quote: | | that is not a challenge in contrast eg to create a useful plasma speaker! |
My linear plasma speaker supply is 1.8 kW, not 3 to 5, and winding the small gauge winding for the high voltage plasma was trivial compared to what wrestling with a heavy gauge for the low voltage 15+ amp on a transformer of twice the size would be.
Thanks for the link, but, as they are a manufacturer and not a retailer, somehow I doubt they'll sell me in quantities less than a hundred. |
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| powerbecker |
Nixie:
The main point of having a transformer in a plasma cutter supply is isolation from the mains, so that the + clamp connected to the work piece can be grounded, so that the operator is safe. Otherwise I could just directly rectify mains and have the workpiece live, so that I can kill myself.
???
When the sec side is floating you can connect it where you like!
"I don't think your estimate is correct for a switching supply, thoug it would be if I went for a linear one, due to the need for a large transformer."
After you get finished it you will know it exactly!
"My linear plasma speaker supply is 1.8 kW, not 3 to 5, and winding the small gauge winding for the high voltage plasma was trivial.."
The powersupply is only a part of it. There is much more to do also the amp I count with!
"...compared to what wrestling with a heavy gauge for the low voltage 15+ amp on a transformer of twice the size would be."
No worry you had to use a lot of thin wires...litz for high frequency 15A...;) |
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| Nixie |
| I was talking about a linear supply, as you invoked the comparison with plasma speakers. I was talking about heavy gauge solid wire for a linear power transformer, to complete the comparison you started. |
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| TwoSpoons |
| You might look at TI s website for app notes on some of their switchmode controllers. A resonant full bridge would do you nicely at that power level. OK, so its going to take some work designing the thing - but thats the whole point really. |
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| Nixie |
| I still can't find any North American RETAILERS (not manufacturers or distributors) of SMPS transformer cores. |
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