TRANSFORMER & PLASMA
Posted by
Arne Chr.Jorgensen
on 1999-12-30 09:56:11 UTC
Hi,
I have not followed the stuff you have discussed about
transformer, David.
This may have been said before, but you know you can add a
capacitor between two faces of a 3phase motor, and
run it on a single phase. ( you loose about 25 % of the power on
the motor, though )
I am pretty sure you can do the same thing with a 3phase
transformer. Why not try it ?
( If the machine already is wired with this transformer )
Here I speculate a bit: Many years ago I installed a special
transformer, that I think was wired as this, but the capacitor and
inductance of the last phase was match in such a way that it would
resonate with the line frequency. The purpose was that this would
keep the line frequency stable, reduce a lot of spikes and noise,
and keep the voltage stable, even during power surges, or even for
short losses of power ( a few cycles ) - so I don't know, but I
would not be surprised if you could in fact get some added bonus
here.
Just a thought.
PLASMA:
There is several parts to a plasma cutter. I would check
manufactures. Like "Themal Arc".
1. Select some unit that has about the same currents as your TIG
or other equipment. You need DC current.
2. Find a torch that fits this plasma unit.
3. All parts of the torch is replaceable, and you may find or
get an exploded view with a part list.
Then things you do need is the Tip and center electrode.
You may even get these parts at a machine shop, because
the throw away the used parts. With this you may design
and make a torch. Often accidents happens, and you may get
a damaged head, - and these may often be repairable.
4. You will also be able to obtain the gas flow, gas mix, cutting
speed charts and current settings for different materials and
thickness.
5. You need to be able to adjust the current in an easy way, and
the best thing would be some feedback control to stabilize the
cutting current.
6. You often uses different gases, one is used more as a pilot
arc between the tip and center electrode, and
another as the "cutting/blowing " gas. All this
info would be found in some brochure about plasma cutting, or
service part document of
the torch.
7. I once saw a very old TIG apparatus, - and found out that you
could probably use a battery charger and ignition coil for a car.
With just one diode, you would get a 50 or 60Hz half
rectified DC from the transformer. The key element would be to
large electrode plates, the size of a dime. The distance
between them would be large enough to let sparks fly, in the case
you short circuit the electrode tip, but large enough that the
spark would rather travel from the tungsten electrode to the work
piece. Crude, but it should work. ( You should shield these
"dime" size internal spark arrestors, so you don't generate to
much electromagnetic noise )
This idea I just presented here, should work on a DC welding
source, that doesn't have any high voltages to start the spark.
( Yes, I do have some crude ideas once in a while ) Other
possible things, could be an ignition transformer for an oil
burner, high voltage circuit for a CRT tube, or - use your
imagination. But the "dime" contact gap, is essential, else you
may destroy this high voltage supply.
8. If you have a tig welder, then skip the stuff I said above.
And from any crude setup, you should learn enough to improve the
design.
9. supply the gases, with good regulators, - you need to be able
to adjust the flow, and should have some way of measure the scsf.
10. You should be able to cut - good luck.
Here is a few figures:
50-100Amps - using Therma Arch cat. # 8-6580 tip & #8-6586
electrode.
Primary gas: N2 at 30 psi ( 35 SCFH)
Secondary gas: CO2 at 40 psi (200 SCFH)
I just gave this figures as an example. In some cases you may use
air as the secondary gas, - and others for the primary.
It all depends on use, material and make. But most gases that
can be ionized, may be used in theory.
A difficult part is that the gas flow, needs to have a steady
laminar flow out of the head assembly. Just as with AC/OXY
cutting, - and there is different designs, like making the gas
swirl in a either cw or ccw direction. The cut will have a better
quality according to the direction of travel and which way the gas
will have its rotational flow or "swirl".
If anyone would try something like this, let us know how it goes !
//ARNE
I have not followed the stuff you have discussed about
transformer, David.
This may have been said before, but you know you can add a
capacitor between two faces of a 3phase motor, and
run it on a single phase. ( you loose about 25 % of the power on
the motor, though )
I am pretty sure you can do the same thing with a 3phase
transformer. Why not try it ?
( If the machine already is wired with this transformer )
Here I speculate a bit: Many years ago I installed a special
transformer, that I think was wired as this, but the capacitor and
inductance of the last phase was match in such a way that it would
resonate with the line frequency. The purpose was that this would
keep the line frequency stable, reduce a lot of spikes and noise,
and keep the voltage stable, even during power surges, or even for
short losses of power ( a few cycles ) - so I don't know, but I
would not be surprised if you could in fact get some added bonus
here.
Just a thought.
PLASMA:
There is several parts to a plasma cutter. I would check
manufactures. Like "Themal Arc".
1. Select some unit that has about the same currents as your TIG
or other equipment. You need DC current.
2. Find a torch that fits this plasma unit.
3. All parts of the torch is replaceable, and you may find or
get an exploded view with a part list.
Then things you do need is the Tip and center electrode.
You may even get these parts at a machine shop, because
the throw away the used parts. With this you may design
and make a torch. Often accidents happens, and you may get
a damaged head, - and these may often be repairable.
4. You will also be able to obtain the gas flow, gas mix, cutting
speed charts and current settings for different materials and
thickness.
5. You need to be able to adjust the current in an easy way, and
the best thing would be some feedback control to stabilize the
cutting current.
6. You often uses different gases, one is used more as a pilot
arc between the tip and center electrode, and
another as the "cutting/blowing " gas. All this
info would be found in some brochure about plasma cutting, or
service part document of
the torch.
7. I once saw a very old TIG apparatus, - and found out that you
could probably use a battery charger and ignition coil for a car.
With just one diode, you would get a 50 or 60Hz half
rectified DC from the transformer. The key element would be to
large electrode plates, the size of a dime. The distance
between them would be large enough to let sparks fly, in the case
you short circuit the electrode tip, but large enough that the
spark would rather travel from the tungsten electrode to the work
piece. Crude, but it should work. ( You should shield these
"dime" size internal spark arrestors, so you don't generate to
much electromagnetic noise )
This idea I just presented here, should work on a DC welding
source, that doesn't have any high voltages to start the spark.
( Yes, I do have some crude ideas once in a while ) Other
possible things, could be an ignition transformer for an oil
burner, high voltage circuit for a CRT tube, or - use your
imagination. But the "dime" contact gap, is essential, else you
may destroy this high voltage supply.
8. If you have a tig welder, then skip the stuff I said above.
And from any crude setup, you should learn enough to improve the
design.
9. supply the gases, with good regulators, - you need to be able
to adjust the flow, and should have some way of measure the scsf.
10. You should be able to cut - good luck.
Here is a few figures:
50-100Amps - using Therma Arch cat. # 8-6580 tip & #8-6586
electrode.
Primary gas: N2 at 30 psi ( 35 SCFH)
Secondary gas: CO2 at 40 psi (200 SCFH)
I just gave this figures as an example. In some cases you may use
air as the secondary gas, - and others for the primary.
It all depends on use, material and make. But most gases that
can be ionized, may be used in theory.
A difficult part is that the gas flow, needs to have a steady
laminar flow out of the head assembly. Just as with AC/OXY
cutting, - and there is different designs, like making the gas
swirl in a either cw or ccw direction. The cut will have a better
quality according to the direction of travel and which way the gas
will have its rotational flow or "swirl".
If anyone would try something like this, let us know how it goes !
//ARNE