Test of Chinese Precipitator Supply

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Finn Hammer
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Test of Chinese Precipitator Supply

Post by Finn Hammer » Tue Nov 14, 2017 11:07 am

All,
There has beeen a lot of speculation about the Chinese Precipitator Power Supply's, so with my new power load at hand, I decided to have a go at testing one of said supplies.
I work with Precipitators on the side, and to my embarrasment, my boss demanded that we also test these cheap supplies, so he bought a couple of these small 200W 30kV types.

This is the setup, where I run the ground wire through the 10A fuse of a multimeter, to monitor current, and load the supply with the full 1.6Mohm of the load, while monitoring the voltage of the output with a 20000:1 voltage probe, as well as monitoring the primary current with a Tek. P6021/134 current monitor.

The supply has 3 trimmers that controll voltage and current.
The voltage is regulated with 2 pots, where the one of them sweeps the output through the range, the other is a kind of bias pot, to the effect that in one extreme, the output is adjustable from 0-10kV, in the other extreme from 4-18kV. These numbers are with the 1.6Mohm load. With a proper 4Mohm load, I am sure it would regulate up to 30kV as advertised.
The current controll is designed to turn the supply off in the case of an arc, so when it is exeeded, the supply shuts down and comes up again after about one second.
IMG_20171114_112142.jpg
I would warn against testing this kind of supplies without a load, as the field controll is really poor, and an arcover is a disaster just waiting to happen. The tell tale of this about to happen is a fierce hissing of corona, and this happens around 20kV, if you continue to turn the voltage up beyond that level, with the wires dangling, an arcover to the core is just around the corner. A punctured insulation just where the wire exits the coil potting, with surface tracking to the core, leading to a carbonized track is impossible to repair, so don't.
I tried this early in my career, so not this time, but I heard the corona, so be warned, it _will_ happen.

The resistance of the load is really too low for the supply, and this means that it cannot reach full voltage at full power, so the maximum output recorded was 18kV 12mA, not so shappy. It will deliver this effortlessly, I had it on the load for 10 minutes, and there was only a 15deg. temperature rize on the heatsink.
At full load, the switching frequency is down to 36kHz. The transformers are run in antiphase, so the output ripple is double that frequency, and quite large, as expected from this topology.

DS1104Z_20171114-111313.png
Full output. Yellow: Output voltage, 10kV/Div. Blue: Primary current, 1A/Div.

Turned down, the voltage is now 4kV, switching frequency up to 74kHz. There is a trimming pot. on the board that allows the voltage to be turned all the way down, but this than has the effect, that the maximum voltage is also lowered, to around 10kV.

DS1104Z_20171114-111342.png
Minimum output. Yellow: Output voltage, 10kV/Div. Blue: Primary current, 1A/Div.

I have not yet the possibility to test this kind of supply on a fusor, so I cannot say that they are, or are not suitable for the task.
I miss a dedicated current regulation, and the biggest challenge will be to route a voltage higher than 20kV to the fusor, instead of to the transformer core.

I think this would be an excellent supply for a demo fusor, and at 73 USD, you can hardly loose.
https://www.ebay.com/itm/300w-30kv-High ... 0005.m1851

Hope this helps,

Cheers, Finn Hammer

Silviu Tamasdan
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Re: Test of Chinese Precipitator Supply

Post by Silviu Tamasdan » Tue Nov 14, 2017 11:30 am

Nice writeup. Unfortunately these don't seem to meet my minimum specs.
Also a caveat for those considering using one of these in the US, they are using 220VAC, so you will either need a step-up transformer or a dedicated 220V outlet (it is available in the US, usually for dryers etc).
There _is_ madness to my method.

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Dennis P Brown
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Re: Test of Chinese Precipitator Supply

Post by Dennis P Brown » Tue Nov 14, 2017 11:35 am

Outstanding work, Finn (as your usual!) Many here will really appreciate your efforts.

Just curious, why not place the supply under oil so it can achieve full potential without arc over?

While 18 kV is still too low for a fusor, the current is fairly decent for that voltage - vastly better than a NST; if the voltage can be pushed to over 20 kV and maintain that current/power level, it might achieve detectable fusion in a small "T" type chamber.

I'm always looking for a method to get a failed project going again on the cheap ... and yes, I wired a 220 - three phase system for my lab. However, I believe the device is single phase or did I read that incorrectly? From the picture, this might be three phase ... . To bad, a DC out put ... can't use it for a voltage multiplier.

Of course, the polarity maters a great deal - is it a negative out put system? Your scope appears to be set on positive trace ...if so, this would never be applicable for a fusor ...

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Finn Hammer
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Re: Test of Chinese Precipitator Supply

Post by Finn Hammer » Tue Nov 14, 2017 12:06 pm

Dennis P Brown wrote:
Tue Nov 14, 2017 11:35 am
Outstanding work, Finn (as your usual!) Many here will really appreciate your efforts.
Thank you for your kind words.
Dennis P Brown wrote:
Tue Nov 14, 2017 11:35 am
Just curious, why not place the supply under oil so it can achieve full potential without arc over?
That would be a good solution, as would potting using proper tecnique.
Dennis P Brown wrote:
Tue Nov 14, 2017 11:35 am
While 18 kV is still too low for a fusor, the current is fairly decent for that voltage - vastly better than a NST; if the voltage can be pushed to over 20 kV and maintain that current/power level, it might achieve detectable fusion in a small "T" type chamber.
As I wrote, with a higher resistive value in the load, the supply would certainly respond with a higher voltage. And 30kV 7-8mA is plausible. From what I read, this is not enough to get any fusion worth talking about.
But my main aim with the test was to see if they get hot, blow up or the like, and they don´t. Pretty neat supplies for the price.
Dennis P Brown wrote:
Tue Nov 14, 2017 11:35 am
Of course, the polarity maters a great deal - is it a negative out put system? Your scope appears to be set on positive trace ...if so, this would never be applicable for a fusor ...
The way the wires exit the transformers, you can have it both ways.

Cheers, Finn Hammer

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Richard Hull
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Re: Test of Chinese Precipitator Supply

Post by Richard Hull » Tue Nov 14, 2017 9:58 pm

Good and interesting report. The final judgement will be seeing it work under a plasma load. If negative and if it can take the first light plasma inrush current without reseting, (big problem with all spellman current limited supplies), then this would make a great entry level supply that might be suitable for low level fusion.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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