To properly explain how a plasma cutter works, we must begin by answering the basic question “What is plasma?  In its simplest terms, plasma is the fourth state of matter.  We commonly think of matter having three states: a solid, a liquid, and a gas.  Matter changes from one state to the other through the introduction of energy, such as heat.  For example, water will change from a solid (ice) to its liquid state when a certain amount of heat is applied.  If the heat levels are increased, it will change again from a liquid to a gas (steam).  Now, if the heat levels increase again, the gases that make up the steam will become ionized and electrically conductive, becoming plasma.  A plasma cutter will use this electrically conductive gas to transfer energy from a power supply to any conductive material, resulting in a cleaner, faster cutting process than with oxyfuel. The plasma arc formation begins when a gas such as oxygen, nitrogen, argon, or even shop air is forced through a small nozzle orifice inside the torch. 

An electric arc generated from the external power supply is then introduced to this high pressured gas flow, resulting in what is commonly referred to as a “plasma jet”.  The plasma jet immediately reaches temperatures up to 40,000° F, quickly piercing through the work piece and blowing away the molten material. The vast majority of plasma cutting systems today can be grouped into either conventional or precision categories. Conventional plasma systems typically use shop air as the plasma gas, and the shape of the plasma arc is basically defined by the orifice of the nozzle.  The approximate amperage of this type of plasma arc is 12-20K amps per square inch.  All handheld systems utilize conventional plasma, and it is still used in some mechanized applications where the part tolerances are more forgiving. Precision plasma systems (high current density) are designed and engineered to produce the sharpest, highest quality cuts that are achievable with plasma.  The torch and consumable designs are more complex, and additional pieces are included to further constrict and shape the arc. 

A precision plasma arc is approximately 40-50K amps per square inch.   portable ac repair serviceMultiple gases such as oxygen, high purity air, nitrogen, and a hydrogen/argon/nitrogen mixture are used as the plasma gas for optimum results on a multitude of conductive materials.how many watts for ac unit In a typical handheld plasma system, such as our Tomahawk® Air Plasma, the electrode and nozzle consumable parts are in contact with one another inside the torch when in the OFF state. central air conditioner repair diyWhen the trigger is squeezed, the power supply produces a DC current that flows through this connection, and also initiates the plasma gas flow. Once the plasma gas (compressed air) builds up enough pressure, the electrode and nozzle are forced apart, which causes an electrical spark that converts the air into a plasma jet. 

The DC current flow then switches from electrode to nozzle, to a path between the electrode and work piece. This current and airflow continues until the trigger is released. Inside a precision plasma torch, the electrode and nozzle do not touch, but are isolated from one another by a swirl ring which has small vent holes that transform the preflow/plasma gas into a swirling vortex.  When a start command is issued to the power supply, it generates up to 400VDC of open circuit voltage and initiates the preflow gas through a hose lead set to the torch.  The nozzle is temporarily connected to the positive potential of the power supply through a pilot arc circuit, and the electrode is at a negative. Next, a high frequency spark is generated from the Arc Starting Console which causes the plasma gas to become ionized and electrically conductive, resulting in a current path from electrode to nozzle, and a pilot arc of plasma is created. Once the pilot arc makes contact to the work piece (which is connected to earth ground through the slats of the cutting table), the current path shifts from electrode to work piece, and the high frequency turns off and the pilot arc circuit is opened.

The power supply then ramps up the DC current to the cutting amperage selected by the operator and replaces the preflow gas with the optimum plasma gas for the material being cut.  A secondary shielding gas is also used which flows outside of the nozzle through a shield cap. The shape of the shield cap and the diameter of its orifice forces the shield gas to further constrict the plasma arc, resulting in a cleaner cut with very low bevel angles and smaller kerf.I often make small projects. However have problems to find a small power supply is not. The problem is not to find a small transformer, However it is big and heavy. Not suitable for my project. But I see in the small appliance production in China.Do not widely used a transformer. However like to use a capacitor replace. Which it smaller and lighter than a transformer. Today I collect these transformerless power supply circuit, so you can select to use in required. Hopefully it will be useful to you. There are 4 circuits, as follows.

Do not touch any part of these circuits. Because you may be hit by electric shocks.Power Supply 9VDC no transformer2 (2.) DC power supply not use transformer3 (3.)Negative Volage Regulator 6V not use Transformer (4.) DC Regulator supply 15V non transformerThis is circuiut power supply 9VDC no transformer,It easy circuit and small size. Volt output = Volt Zenerdiode. Output Current 100mA (min).It easy circuit and small size. Power Supply 9VDC no transformer You may know the reason that make power supply circuit have large-sized as a result , because transformer. Way this out be must not use. We use capacitor replace as a result work also well. In Power Supply 9VDC no transformer circuit . The this base equipment have zener diode perform heal voltage be stable or 9V DC Regulator. but kind this circuit be defective that current not tall sir. The detail is other , see in the circuit sir.Work cycle is C1 and R1 acts reduced AC Current Source to rectifier current is a DC Volt by bridge diode circuit which D1-D4 acts to change AC to DC with the C2 makes the filtering power DC to smoother will a zener diode acts to reduce voltage is equal to the number of volt zener diode and C3 will DCV voltage output that is more smooth.

If friends with look for Mini power supply 6V sizes. That give negative voltage. I begs for to advise this circuit. It has prominent small-sized point and light weight. Because do not use Transformer. But still can use current get 0.07Amp not exceed and when see the circuit. Think use Zener diode control voltage be stable that 6V and have transistor enlarge the trend equal to that want. And still systematically protect through the circuit or Shot Circuit Protect with Transistor as well. The detail is other , see in circuit picture has yes. Friends at don’t like large-sized of a transformer. I begs for to advise 15VDC regulator power supply can give the trend current get low about 80mA not exceed. But enough will usable small-sized circuit has comfortablely. Think I uses Zener Diode be formed help maintain one’s position volt be stable , and use Transistor help enlarge current tallly increasingly. Make this circuit is usable well , But friends as a result must use the carefulness specially , because apply to the level voltage tall directly yes.

Today John Lam send feedback to me, It is very good content. Read below: The use of transformerless power supply dated back at least 15-20 years ago if not earlier. It was a historic innovation at that time when transformer power supply that is heavy, bulky and cost-ineffective is the mainstream power supply in small electrical and electronic gadgets.Transformerless power supply are normally for loads that consume a small current ranging from a few mA to a few tenths mA. In recent years, they are also designed to supply larger current like those inside a LED light bulb. Every transformerless power supply is in fact custom design specific to the current load of the application, and is put inside an insulated enclosure. The risk of electric shock is minimal. In comparison to its transformer counterpart, it is more cost-effective in manufacturing and more compact. They are not supposed to be used as a general power supply.For anyone who are interested in this kind of circuits, treat them for educational purposes, learn how and why the circuits work.

One can surely try to build one to suit a specific application, but certainly not using it as a general-purpose power supply.Since Anand mentioned the first circuit is used for a 0.5W LED night lamp. Let’s see how the circuit works.R2 is used as a choke to limit inrush current, or limit the current in case both the 0.33uF capacitor and R1 fail before F1 will blow off. R1 is a bleeder resistor for discharging the 0.33uF after plug off. Both R1, R2 and F1 are safety features.The circuit can theoretically supply 22.9mA current.The equation used is current, I = V / (Total impedance of R1, R2 and 0.33uF)Since R1 and 0.33uF are in parallel and then in series with R2, the calculation is a bit complicated to show here. In addition, the actual calculation also have to take into consideration the 2 x 0.7V = 1.4V voltage drop of the bridge rectifier. For those interested, google on “how to calculate impedance of RC circuit” to learn more.Next is the bridge rectifier that rectifies the main AC sinusoidal wave into full-wave pulsating DC.

The 470uF electrolytic capacitor smooth the pulsating DC to decrease the ripple voltage. Then the ZD1 regulates the output DC voltage to 9V.As mentioned earlier, the circuit can supply 22.9mA current, depending on the color of the LEDs used, with 9V output, it provides sufficient voltage and current for either 3 (white LED) or 5 (red LED) connected in series. That’s how the circuit works.Power dissipated by R2 = (0.023)^2 * (20) = minimal. Any resistor rated 1/8W up is fine.AC is 220V that translates into a peak voltage of 312V, so voltage rating of the 0.33uF capacitor should be 350V or higher.Power dissipated by R1 is minimal (you do the math), the 1W rating specified is fine.For the bridge rectifier, 1N4007 is rated at 700Vrms reverse voltage and 1A, and is more than sufficient for this circuit. 1n4004-1n4007 are all fine.Since the zener diode is 9V, the rating of the 470uF electrolytic capacitor can be 15V and up.When no load is connected, all the current will pass through the zener diode when it has the maximum power dissipation, W = V*I = (0.023) * (9) = 0.225W.