Thermacut® has recently launched a new HD range of the EX-TRAFIRE® plasma cutting systems. What you can expect and where are they applicable? Read on to find out more.

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  • řezání plazmou
  • ex-trafire 45hd
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These powerful plasma cutting systems are designed to meet the rigorous demands of continuous industrial use. The EX-TRAFIRE®HD plasma cutters have a 100% duty cycle for high-quality long cuts in thick sheet metal up to 50 mm and more. In addition to cutting, grid cutting and gouging, they also have an optional marking function. These reliable and durable machines have found a place in many different segments of the industry due to their versatility.

The heavy industry segment

Thanks to their high output power, these machines can deliver continuous top cutting performance and high-removal-rate gouging, which can be used, for example, in the maintenance and manufacture of excavators, tractors or mining machinery. The EX-TRAFIRE®HD range of plasma cutters offers plenty of power for sheets up to 50 mm thick, a wide range of applications, and interfaces for intelligent networking.

Using plasma cutting in heavy industry segment

General fabrication

The EX-TRAFIRE®HD line of plasma systems can do a lot and withstand even more for your industrial production. They provide clean cuts without the need for subsequent work, helping you to achieve higher productivity.

Plasma systems can do a lot for your industrial production.

Structural segment

On the shop floor there is often a need to manually cut large bridge sections or building components. Operators appreciate a flexible plasma cutter that is easy to use and can cut and gouge (weld edge preparation) all types of steel and aluminum.

Manual cutting of large bridge sections or building components.

Shipyards & Offshore

Typical application for the EX-TRAFIRE®HD plasma systems. The construction of ships or foundation structures for offshore wind turbines and drilling rigs requires precise cuts for high-quality components without delay. These new plasma systems are not only extremely robust, productive, and powerful, but also deliver extremely clean and accurate cutting results.

The construction of ships or foundation structures for offshore wind turbines and drilling rigs requires precise cuts.

Automotive & Transport

EX-TRAFIRE®HD plasma systems are also ideal for the manufacture and repair of vehicles and their components. They are ideal for heavy cutting and gouging in production and are perfect for semi-finishing and repair work.

EX-TRAFIRE®HD plasma systems are also ideal for the manufacture and repair of vehicles and their components.

Steel Mills & Steel Service Centers

If you process coils and profiles after fabrication, or if you cut sheet metal for further processing, you need to achieve a high cutting rate and good edge quality at the same time. The powerful EX-TRAFIRE®HD plasma systems are ideal for strong, rapid cuts and a wide range of applications in steel mills and steel service centers.

The powerful EX-TRAFIRE®HD plasma systems are ideal for strong, rapid cuts and a wide range of applications in steel mills and steel service centers.

The energy segment

The EX-TRAFIRE®HD plasma cutting systems are suitable for a wide variety of uses in the energy industry, from pipeline construction to wind power plants and right through to turbines and overhead power lines.

The EX-TRAFIRE®HD plasma cutting systems are suitable for a wide variety of uses in the energy industry, from pipeline construction to wind power plants and right through to turbines and overhead power lines.

The HD range of the EX-TRAFIRE® plasma cutters offers plenty of power for cutting sheet metal up to 50 mm thick and a wide range of applications, including a handy sheet marking function. Make the most of 100% duty cycle for manual cutting up to 50 mm and above, and gouging when removing wear resistant coatings or preparing welds. They are also excellent for mechanized cutting of semi-finished products and are ideal for continuous cutting. All EX-TRAFIRE®HD systems have flexible interfaces that make it easy to implement automated 3D robotic applications.

These plasma cutting systems are machines you can rely on for your daily work, and they improve your productivity. There is nothing more to say, just try it.

Are you interested in plasma cutters? Visit our website, where you can find the complete range of plasma power supplies by Thermacut®.

Not sure which one to choose? We are here for you! Contact us at

Text:               Thermacut, k.s.
Photo:            Archive of Thermacut, k.s.



EX-TRAFIRE® plasma cutters have been an important part of the Thermacut® portfolio for several years, and they are offered to our customers worldwide. A few years ago, one of them was purchased by the Czech Assembly Works company from Uhersky Brod. They got the EX-TRAFIRE®75SD plasma cutter.

Customer using EX-TRAFIRE® 75SD

The company operates worldwide in the field of steel construction for production sites for large wooden materials for the furniture industry, flooring products, or kitchen production. The basic equipment requirement is therefore the ability to thermally cut steel and thin plates up to 20 mm thick (mild steel, Hardox®, aluminum, stainless steel, tubes, sheets) and to cut different shapes at different angles for the creation of such structures.

We have asked Mr. Martin Kočica, the founder and supervisor of the company, for a short interview. He briefly introduced his business, told us what demanding tasks the equipment must fulfill, and why he decided to purchase a plasma cutter by Thermacut®.

Mr. Kočica, tell us please, what is your business about?

Locksmith production, installation of air conditioning, and filtration equipment to achieve the lowest possible amount of production waste into the air.

What does your work involve in practice?

Our activities include building equipment, installation of piping, steel construction, etc.

Why did you decide to invest in a plasma cutter?

We decided to invest mainly for practical reasons. We often need to cut materials and to make irregular shapes, where the angle grinder isn´t a suitable tool to use because of difficult manipulation.

What are the main advantages you see in buying a plasma power supply?

The most important advantage we can see is a considerable decrease in consumption of grinder pads / discs for Hardox® and other steel sheets resistant to abrasion. Other benefits we can highlight are high cutting speed and perfect torch flexibility, even in narrow spaces that are difficult to reach.

How often do you use plasma cutting technology for metal cutting?

On a daily basis.

Why Thermacut®?

Because Thermacut® is a Czech company offering cost-effective machines. We also like the fast communication, availability of consumables, and technical service.  

Would you recommend the investment in a plasma cutter?

Yes, I would.

Have you already experienced our after-sale service? What has it been like?

Yes, I have, and we have had no problem with that.  

Thank you for the interview, your time and we wish you good luck in your business.

Are you interested in plasma cutters? Visit our website, where you can find the complete range of plasma power supplies by Thermacut®.

Not sure which one to choose? We are here for you! Contact us at

Text:               Thermacut, k.s.
Photo:            Archive of Thermacut, k.s.



Are you new to plasma cutting and uncertain about which gases to choose to achieve the best results? Although there is a lot of information everywhere, the average operater, especially a newbie, might get lost quickly. Let´s clear it up once and for all.

Depending on the metal that you´re cutting, you´ll require different types of gases, or a special mixture of gases. In this article we will focus on their main characteristics and recommend which metals various gases are suitable to cut.


The most common plasma cutting gases include compressed air, oxygen, nitrogen mixtures (N2/CO2; N2/H20; and (N2)2/air), and argon-hydrogen. All of them work relatively well on thinner sheets of metal, one-half inch or less (≤ 12 mm), but when the plate thickness increases, fabricators typically use a combination of these gases to improve production.



Compressed air is the most versatile plasma gas, providing good ratio of cut quality and speed on low alloyed steel (mild steel), stainless steel, and aluminum. The big advantage is lower operation cost because it´s not necessary to purchase it. On the other hand, it is necessary to maintain a compressor on a regular basis, and keep it free from any particles or oil mist and moisture. Using compressed air, some kind of oxidation and nitriding can occur on the cut surface, which can cause porosity with a negative impact on the following weldability. The issue is usually corrected by using high-quality weld wire with denitrifiers afterwards.

Suitable for metals:Mild steel, stainless steel, aluminum
Recommended material thickness:Up to 1 inch (≤ 25 mm)
ApplicationCutting, gouging, marking (EX-TRAFIRE® HD line)

The best solution for EX-TRAFIRE® plasma cutting systems is a good-sized air compressor with a gas flow output more than 200 lpm (7.1 scf/m) depending on the type of power supply. The gas pressure value should be at least 0.8 bar (11 PSI) above the required dynamic cutting pressure, depending on the torch type. For example, the FHT-EX®105RTX torch at 105 A requires dynamic pressure of 5.2 bar (75 PSI) / 140 lpm (5 scf/m) for cutting applications. That means the input pressure into the power supply should be at least 6 bar (87 PSI) / 170 lpm (6 scf/min) – including a little buffer reserve. The more lpm the better.


In industry, oxygen is the number one gas for cutting mild steel because of clean, good-quality cuts, leaving only a slight layer of dross (mineral waste formed on the surface of molten metal), that´s ease to remove from the kerf due to the low surface tension. In addition, cutting with oxygen increases cutting speed in comparison with other plasma gases. Oxygen works effectively in combination with other secondary fuels as well. Oxygen isn´t recommended for cutting stainless steel or aluminum.

The main disadvantage of oxygen is the high gas price, and in some cases slightly reduced consumable lifetime. It also doesn´t work on shiny surfaces.

Suitable for metals:Mild steel
Recommended material thickness:Up to 1 ¼ inches (≤ 32 mm)

Oxygen isn´t used and allowed for the EX-TRAFIRE® plasma cutting systems.


Earlier, nitrogen was used in legacy plasma torches. Nowadays nitrogen is often used for higher current plasma systems, for cutting materials up to 3 inches (≤ 75 mm). The best results are achieved while cutting stainless steel and aluminum, but fair cut quality is achieved on mild steel too, although some dross may occur. By itself, it’s most effective on smooth and shiny thin sheets. A bit advantage of nitrogen is excellent cut quality and extended consumables lifetime. On the other hand, nitrogen is an expensive gas.

For thicker metals it´s better to use nitrogen in combination with carbon dioxide, with air, or with argon as a secondary gas.

  • CO2 slightly improves surface finish, increases cutting speed and extends consumables lifetime
  • Air is the best secondary gas when you´re using a nitrogen plasma system
  • Water as a secondary, if the system allows, must be used with a water table
Suitable for metals:Stainless steel, aluminum
Recommended material thickness:Up to 3 inches (≤ 75 mm)

Referring to the first paragraph, compressed air contains around 75% nitrogen, so nitrogen and its mixtures are also suitable gases for the EX-TRAFIRE® power supplies. They are recommended for stainless steel or aluminum cutting.


Argon is a rare, therefore expensive, inert gas, unreactive with the metals being cut. Using argon while cutting is advantageous. It stabilizes the arc and prevents atmospheric contamination of welding pools, but it can´t work alone because of its low conductivity.

Hydrogen is a perfect thermal conductor and can quickly cool hot metal surfaces. For these reasons it is optimal for cutting aluminum and high alloyed steel (stainless steel). Although it has excellent conductivity, its low atomic weight prevents it from having high kinetic energy. Just like argon, it must be combined with other gases.

The standard argon-hydrogen mixture is 65% argon and 35% hydrogen. This argon-hydrogen mixture is the best for thick stainless steel and aluminum plates that exceed 3 inches. For cutting mild steel it isn´t recommended. In addition to cutting, the argon-hydrogen mixture is also suitable for plasma gouging on any materials. Argon-hydrogen provides a straight, very smooth cut, and an almost polished surface on high alloyed steel (stainless steels). The combination offers the maximum cutting capacities. Due to the high purchase price, operation with argon-hydrogen is less economical.

* Prior to use, ensure that your system is safe and compatible with argon-hydrogen gas.

Suitable for metals:Stainless steel, aluminum
Recommended material thickness:Up to 4 inches (≤ 100 mm)
ApplicationCutting, gouging, marking

Argon and its mixtures are suitable for the EX-TRAFIRE® power supplies for marking application using the EX-TRAFIRE® HD line. Compared to compressed air, marking with argon will prevent grooves that are too deep and wide. In other words, you can achieve better results.


Considering the most common materials you cut, their thickness, required cut quality and your financial requirements, here are some brief conclusions:

  • The most economical and versatile gas for plasma cutting is clean compressed air, which fits for mild and stainless steel, and aluminum as well
  • Oxygen is the best for mild steel cutting, where air is used as a shielding gas, with good cut quality, fast cutting speed and only a low, easily removable dross
  • When you need to cut mainly stainless steel and aluminum, use nitrogen plasma in combination with CO2 to reach the best cost-performance ratio
  • For very thick stainless steel and aluminum plates, argon-hydrogen in combination with nitrogen as a secondary gas is the best choice to get a perfect cut quality for the cost

The most suitable plasma gas for the EX-TRAFIRE® plasma cutting systems is clearly compressed air. The main benefits are reduced initial and operating cost, and easy accessibility (just a compressor with correctly set parameters).

A possible alternative for cutting stainless steel or aluminum is nitrogen. Using nitrogen requires only slight adjustment of cutting parameters compared to the compressed air.

For the purpose of marking plates with the EX-TRAFIRE® HD line, the best choice is clearly argon. Using a special range of consumables for marking applications, you can achieve nice, smooth, mild, and narrow grooves.

We hope you found this article useful. If you need any advice in this area, do not hesitate to contact us. You can contact us at this email address:

Text:               Thermacut, k.s.
Photo:            Archive of Thermacut, k.s.



In many areas of industry, heavily stressed functional surfaces are reinforced by deposition welding protective coatings. During the service life of a component, it often makes sense to remove worn protective layers and to apply new protective coatings to the heavily stressed areas. Here, the plasma gouging process offers an economical and ecologically responsible alternative to the conventional removal process with carbon rod electrodes.

In cooperation with a German specialist for the production and regeneration of complex wear protection systems, Thermacut® has qualified plasma gouging as a process suitable for the thermal removal of worn wear protection layers on tool joints and stabilizers on components from the offshore industry.

In preliminary tests with Thermacut® FHT-EX® plasma gouging torches, the suitability of the process for the common iron- and nickel-based wear protection alloys was first demonstrated. Furthermore, the specific advantages of the plasma gouging process were shown, especially in comparison to the conventional process with carbon electrodes. 


  • higher material removal rate,
  • lower noise emissions,
  • easier handling,
  • smoother and cleaner surfaces
  • no rework
  • more targeted process control 

Due to the high thermal effect (22 kW electric arc power) of the plasma jet, coating thicknesses between 1 and 8 mm can be removed in a single operation. Although the PGP (plasma gouging process) can be used effectively with flat and irregular surfaces, it reveals its full advantages in automated use with rotationally symmetrical components such as tool joints and stabilizers. Through continuous movement of the Thermacut® FHT-EX® plasma torch, old wear protection coatings are removed evenly with constant surface quality. The component surfaces can thus be protected for renewed use with new welds after removal by PGP without further post-processing.

Check out both videos showing FHT-EX® torches used for gouging 

Are you interested in the modern and capable FHT-EX® plasma cutting and gouging torch made by Thermacut®? Visit the web site, download a catalogue and contact your local Thermacut® office.

Text: Thermacut, k.s.
Photos: archive of Thermacut, k. s.



The purchase of cutting equipment is a considered long lasting investment, irrespective of the type of cutting technology used, they all share one common factor: They have to be maintained.

It is important that the equipment is serviced and maintained on a regular basis in order to keep it in tip top condition, equipment that is neglected or poorly maintained might fail in service, leading to costly downtime, repairs, scrappage or even personal injury.


EX-TRAFIRE® systems are robust and easy to maintain.

Checks prior to use
Prior to every use, check as a minimum the following: The system is not connected to the mains power supply and is in the “OFF” state. Inspect the power cable, torch, lead and return cable condition for cuts, breaks or other damage.
Check the torch safety trigger, ensure that the consumables are correctly installed and not worn out, remove any debris that may have stick between the shield and nozzle. The torch O-ring should not be dry, apply a thin coat of silicone grease. Connect the system to the power supply, back-off the pressure on the regulator, connect the air line, switch the system to the “ON” state, allow the system to run the diagnostic check, increase the air pressure to the desired value, when all checks have been done and any issues have been addressed, proceed with use.

Once a week examine and check the torch, retaining cap, and safety switch pins. Ensure that the LED3 safety indicator is fully functional. It indicates a loose or damaged retaining cap.

Every 3 months (dependent upon use and environmental conditions)
Clean the dust from inside of the power supply use clean dry compressed air. It is advisable to perform a full examination of the torch. Check the torch trigger safety mechanism for free movement, any signs of cracking in the torch body or exposed wires.*

Every 6 months (dependent upon use and environmental conditions)
Use a vacuum cleaner and/or clean dry compressed air on the inside of the power supply (standard compressor with max. pressure up to 10 Bar). Ensure that the power supply is disconnected from the input power prior to removing the cover.*

If upon inspection any damage is found do the following: Mains power lead/plug, torch, torch lead, airline hose, connectors, or filter components. Access the damage, repair or replace as necessary. Do not operate the system until fully compliant.

Yearly (dependent upon use and environmental conditions)
We strongly recommend doing the safety test based on VDE 0105-100.

Purging/draining the built-in filter
EX-TRAFIRE® power supplies are equipped with a built-in float type auto drain filter.

*When cleaning the power supply using compressed air, it is advisable to take precautions for exposure to dust and contaminants. Take care of yourself, work colleagues and the environment. Wear PPE (Personal Protective Equipment) as required by local law.

Was this article interesting? For more information please do not hesitate in contacting us at the following email:

Text:     Thermacut, k. s.
Photo:  archive of Thermacut, k. s.



The Thermacut Smart Solution label signifies a wide range of cost effective, evaluated, high-quality products that are manufactured in the EU and comply with existing quality and work-place safety regulation standards. THERMACUT® replacement filter cartridges are suitable for KEMPER® fume extraction systems. They improve performance, extend the service life, and deliver filtration efficiency values that are considerably better than the permitted threshold limit.

Filter cartridges are a part of a large filtration system used during cutting and welding applications. After the fume extraction, smaller or larger particles settle on the surface of the cartridge elements.

The filter´s material can separate ultrafine dust particles down to 0.1µm or even smaller. Compare that to commonly used filters.

RESULT? Efficient filtration and longer filter lifetime!

While cleaning, you reverse the process and the coated filter surface is easier to clean.

  • Work-place safety regulation compliant. 
  • Minimizes the amount of particles that stick to the filter after cleaning. 
  • Less pressure is needed for cleaning. 
  • Less energy
  • Less noise radiation 
  • Increased filter service life.


High Performance

  • IFA filter class “M” for high levels of dust & smoke contaminants (in accordance with the standard DIN EN60335-2-69, annex AA) 
  • Large filter surface area reduces the filter load and extends its service life. 
  • Designed for continuous industrial operation.​

 Versatility ​

  • Long-life blended filter material for capture of dust and fumes
  • IFA-certified filter materials
  • For indoor and outdoor use in fume extraction systems
  • For plasma, laser and oxyfuel cutting and welding.

Easy to use

  • 242 g/m2 high-quality ePTFE filter material 
  • Compact, extremely stable cartridge filters 
  • Quick and easy installation 
  • Reduced service and maintenance costs

The replacement filter cartridges are available in various lengths, diameters, and filtration surfaces.

400 mm length – 4 m2 filter size

600 mm length – 10 m2 filter size

1200 mm length – 20 m2 filter size

Ordering information

Click and download the plasma catalogue right here: The replacement filter cartridges ca be found under the ACCESSORIES section.

Thank you for reading this article. If you need any further assistance with choosing the right filter cartridge, pleasecontact us. We are fully at your service at the following email address:

The filter cartridges shown above are not original cartridges, but high-quality replacement filters in OEM quality, which are made from certified filter media.

Text:  Thermacut, k.s.
Photos:  archive of Thermacut, k. s.

*THERMACUT® is registered trademark of THERMACUT, K.S. and may be registered in Czech Republic and/or other countries. All other brand names and trademarks are properties of their respective owners. THERMACUT® is no way affiliated with KEMPER®.



The potential uses of plasma cutters are vast. The cutting technology is well-known and widely used in industrial plants processing flat metallic materials, such as sheet steel of various thicknesses. However, plasma cutters will also find use in smaller companies that focus on cutting, bending or otherwise shaping thin metal sheets. A typical example of such use is tinsmithing. Here the small yet powerful plasma cutter becomes an invaluable assistant.

Tinsmithing has become a traditional craft that is indispensable to construction of new buildings or renovation of older houses, apartments and other buildings. It is the last step of the construction process, ensuring that the structure is leak-proof and that the roof fulfills its protective function. Tinsmithing does not involve just the construction of eaves as many might imagine, but also includes metal plating the chimney, valley, and windowsills, and installing drainpipes, gable trim etc.

It is often necessary to make cut outs in metal or saw a hole into it, sometimes repeatedly — for example, when connecting or anchoring eaves. Thermacut’s EX-TRAFIRE®30H plasma cutter is ideal for these purposes due to its favorable price-to-power ratio.

Let’s take a look at what to do step by step.


1. Step

First, we prepare the table for cutting (the table differs from the classic workshop table). Place the template and draw the openings onto the metal sheet. You can also use a pair of compasses to achieve perfectly round circles. Secure the template with clamps.

2. Step

To cut the holes, we will use handheld plasma cutter EX-TRAFIRE®30H. Set the power supply to the appropriate cutting parameters according to the instruction manual. In our example, we cut a 1 mm thick sheet using consumables from the 30 A series.

3. Step

And done! Quick and simple!

Sometimes an inspiring video can say more than a thousand words. And we made one for you! Just click the link below:

We can use the same process to cut circular holes to create a drip edge. You can see the end result in the pictures below. 

The EX-TRAFIRE®30H single-phase plasma cutter, which we are presenting here, is a handheld cutting system with non-detachable FHT-EX®30H torch with a 4 meter length and a non-detachable work conductor with a 6 meter length. It also features an ergonomic torch handle which reduces fatigue during long-term use. The system is compact and highly flexible for cutting in hard-to-reach places. It is particularly suitable for cutting sheet metal up to a thickness of 10 mm while providing sufficient power reserve.

You can find more information at or scan the QR code below to take a look at videos on the Thermacut YouTube channel.

We hope you liked the article. If you need additional information or advice, do not hesitate to ask. You can contact us at:

Text:      Thermacut k.s
Photos: Thermacut, k. s. archive 

Thermacut®, The Cutting Company®, EX-TRAFIRE®30H, FHT-EX®30H, EX-TRAFIRE®SD are registered trademarks of Thermacut, k.s. and may be registered in the Czech Republic or other countries.  



When selecting a suitable air plasma arc power supply, it is important to consider several key criteria.

To achieve the maximum financial and performance benefit from an air plasma arc power supply, analyse the following prior to making a purchase. 

As in the case of many tools and devices, making the right choice is important, taking time to compare purchase cost, performance, job site suitability and running costs prior to purchase can save having regrets when its too late, with Thermacuts® guidance, making the right choice is less of a minefield.

Ex-trafire Thermacut


Decide on what the intended use of the plasma power supply will be, manual cutting, gouging, machine or combined cutting applications.


The most common material types that are cut using the air plasma arc process are: Carbon steels, Stainless Steels, Nickel alloys, Aluminium etc. The air plasma arc process can be used to separate any conductive material.  


An important factor to consider is the duration of the cut especially when using an automated or CNC process. The maximum duration of the cut is determined by the duty cycle of the power supply, when the duty cycle is exceeded, the power supply shuts down to protect itself from overheating, after a cooling down period work can resume. An 80% duty cycle is considerd to be an excellent performance, then there is the 100% duty cycle EX-TRAFIRE®75SD. Non-stop cutting, No down time, No frustration.

Information on the duty cycle is stated in the EX-TRAFIRE® catalogue for every power supply type, or see the specifications in the manuals. 


For manual cutting, the recommendation is to select the power supply with the closest performance specification for the range of material to be cut. (This is identified as “material thickness” in the cut charts.)

When chosing a power supply for machine cutting, consider the material thickness to be cut and compare it to the mid-range value on the cut chart. Below is an example taken from the FHT-EX®105RTX torch operator manual.


The customer frequently cuts 10 mm thick Mild Steel and occasionally 20 mm thick Mild Steel.

The 75 A cut chart in the operator manual for the FHT-EX®105RTX torch indicates that the 10 mm thickness is a mid-range value, whereas the 20 mm thickness is close to the bottom of the cut chart. 

Review of the 100 A cut chart in the FHT-EX®105RTX torch operator manual shows the 20 mm thick Mild Steel in the mid-range of the cut chart. Based on this information, the EX-TRAFIRE®100SD power supply is the most “Fit for purpose” option as it covers the customers need to cut 10 mm and 20 mm Mild Steel. By using the cut chart amperage and thickness values, cut quality and system performance will be opitimised.

What else to remember?


“C” type breaker is recommended. Check the Specification table in the operator manual for the I1 RMS current value and choose the next highest nominal breaker value.

Ensure that the electrical connection (input voltage, circuit breaker) comply with the specification of the intended plasma power supply (see the operator manual – Chapter: Specification). Where the electrical input is not suitable, the options are to modify the electrical input or to use an alternative plasma power supply. 


The minimum internal diameter of the air hose or tubing that can be used for the feed to the power supply is 8 mm (I/D = D8). The recommended air pressure from the compressor/distribution network is 7-8 bar, however 6 bar is the minimum.  


In the event that a mains input power cable extension is required for the EXTRAFIRE®45SD, 55SD, 75SD and 100SD three-phase power supplies, it is advisable that the extension cable is the “armoured” type with a minimum wire cross section of 6 mm2 for lengths up to 15 m, and a wire cross section of 10 mmfor lengths over 15 m.

Single-phase power supplies, EX-TRAFIRE®30H, 40SD and 45SD require an extension cable with a wire cross section of at least 2.5 mm2. ,


There is a DC voltage present between the electrode (hafnium insert) and the material to be cut. The voltage value depends on the distance between the hafnium insert and the material to be cut. The greater the gap, the higher the voltage. For example: When a distorted or uneven sheet of metal is to be cut and the operator sets the value of 140 V on the portal in accordance with the cut chart (which can for example equate to a 2.8 mm torch to work distance). When performing the cutting, the torch moves up and down following the contours of the material in order to maintain the set distance between the torch and the material. The portal cannot read the voltage value of 140 V, therefore the divider must divide the voltage in a given ratio (50:1, 40:1: 20:1 etc.) so that the portal can read the voltage. (the voltage value can have a critical influence on cut quality and consumable life – see the cutting charts)EX-TRAFIRE® power supplies are pre-set at the ratio of 50:1 (this value is also used for the EX-TRACK® mobile cutting system).

Where an alternative divider ratio is required, this can be easily set using the DIP switches as shown in the operator manual.​

Some portals need a real arc voltage value (for example, the above mentioned 140 V). It is not technically possible to set such a ratio directly on the voltage divider from the power supply nor to take it from the CNC connector on the rear side of the power supply. What is possible, is to take this voltage directly from the power supply – namely from the work cable and the power line on TCS connector.  


The connecting CNC cable is not included with the power supply package. In most cases it is supplied with the portal. In the event that a CNC connection cable is required, it can be ordered as an accessory under the part number EX-0-803-004 with a cable length of 6 m.

We hope you found this article useful. If you need any advice in this area, do not hesitate and contact us. You can contact at this email address:

We also recommend other related articles called “Package content of EX-TRAFIRE® sets” and “Competitive advantages of EX-TRAFIRE® plasma power supplies”. 

Text:    Thermacut, k. s
Photo: archive of Thermacut, k. s.



To get the best quality plasma arc cutting results, it is necessary to be aware of the main factors that affect cut quality. This article explains what those factors are!


  • Consumables, correct rating/condition​
  • Amperage (Current)​
  • Plasma arc and Shield gases​
  • Arc voltage​
  • Torch height​
  • Cut speed​  
  • Kerf width


Good cut quality can not be expected if consumables from an incorrect rating are used, cut charts give good advice on what is the best amperage for a given thickness. The condition of consumables is critical, ensure that all parts are fit for purpose


Amperage is the strength of a current of electricity expressed in amperes. Current is the movement of electrons through an electrical circuit. A higher current level usually results in less dross for a given material thickness. 

Ic = 260 Amp
Thickness 25 mm, mild steel, cutting speed 1685 mm / min.

Thermacut cut quality
​ A lower current level usually results in better edge quality and squareness for a given thickness but can result excessive dross formation.

I= 130 Apm
Thickness 25 mm, mild steel, cutting speed 550 mm / min

Thermacut cut quality
Lower current consumables typically have a longer operating life than higher current ones, especially when cutting with oxygen.


Purity – It is essential that the following gases are delivered to the plasma arc system in the listed levels of purity. Failure to do so could result in poor cut quality, poor consumable life, and overall degradation in system cut performance.

O2 and N2 with oxygen processes:

  • O2 = 99,5 %, N2 = 99,99 %

N5 & H35 with inert processes:

  • H35 – 99.995 % pure (H35 = 65% Argon, 35% Hydrogen)
  • N5 – 99.98 % pure (F5 = 95% Nitrogen, 5% Hydrogen)

Air: clean, dry and oil-free

Methane: 93 % pure

Plasma gas – this is ionised gas/gases used during the cutting process of conductive materials, the plasma gas exits the nozzle orifice in the form of a plasma arc cutting stream.

Typically used plasma arc gases:

  • Compressed Air
  • Oxygen
  • Nitrogen
  • Argon-Hydrogen 

Shield or Secondary gas – surrounds the plasma arc, in some torches it assists in arc constriction, assists in cooling the nozzle and shield. Can be used to create an oxygen free atmospheric zone around the cut edge, producing a cleaner cut edge. The shield gas used is dependent upon the choice of plasma arc gas.

The selection of gases depends on the type of material that is being cut (mild steel, stainless steel, aluminium, etc.) and the desired cut quality. Recommended gas combinations are published in the operator manual by the manufacturer.


Arc voltage control (AVC) monitors the circuit voltage and adjusts the height of the torch in accordance with the pre-set values. The torch height to work has an effect on the bevel angle, and overall quality of the cut. The arc voltage control maintains the pre-set torch to work distance on uneven surfaces.

There is a relationship between Arc voltage and cut speed. As the cut speed increases, the arc voltage decreases and vice versa. Mechanised cutting programs have speed percentage values of the straight line speed, this enables the cut speed to automatically reduce when cutting circles, irregular shapes and change of direction at corners, also the “Ramp up” and down at the start and end of a cut, this can cause the formation of dross in slower speed areas of the cut but with a better bevel angle. 

Relationship between arc voltage and cut speed

THC (torch height control) reacts to travel speed: The torch will lower as speed decreases or rise as speed increases. THC must be turned off or “AVC Disabled” when speed decreases.


With the plasma arc torch in the resting position, the first stage of the cutting process is where the torch moves to the torch to work height for piercing, the piercing height is pre-programmed to suit the material thickness, in most cases the piercing height is between 1.5- 2 times the cut height. Cut height is the torch-to-work distance maintained during a cut cycle.

How does it work?

1. The THC is “blind” prior to the cutting process

2. In order to establish the zero height point, the torch cap or sensor is required to touch the upper surface of the workpiece.

3. The THC lifts the torch from the zero height to the piercing height in accordance with the cut chart settings.

4. After piercing of the workpiece, the THC lowers the torch to the programmed cut height

5. AVC is turned ON (AVC enabled)


Correct cut speed can produce dross free cutting. To obtain the “Best” cut quality from a system, use the cut chart data provided by the manufacturer. The precise operating data (such as amperage, arc voltage, torch-to-work distance and cut speed) for a given material thickness should be in the mid-range of the cut chart.

Example: How cut speed affects cut quality

Cut speed is too slow (Thick heavy dross)/Cut speed is correct (Dross free) /Cut speed is too fast ( Thin sharp dross)


Kerf width is relevant to the dimensional accuracy of the part. A wider kerf is usually caused by a slower cut speed or excessive power. Kerf width = 1.5 – 2.0 x orifice diameter of the nozzle.

Kerf is the void created by the cutting process (or the volume of material removed).

We hope the article was useful for you. We also recommend another article related to the theme, “Reading the cut”.

If you need any further help, please contact us at the following email:

Text:        Thermacut, k. s., Jan Košárek

Photos:   archive of Thermacut, k. s.



EX-TRAFIRE® SD plasma cutting systems have been engineered out of a fully conceptual design, in which all components have been optimized and perfectly coordinated to deliver a class beating performance.


All EX-TRAFIRE® power sources feature an integrated GRID cutting mode which automatically switches between the pilot arc and the main arc. This feature removes the need to regenerate the arc when an air gap is reached, the arc remains in pilot arc mode until material is detected.


The EX-TRAFIRE® 75 and 100SD plasma power supplies possess a unique attribute “Extraboost”, supplying up to an incredible 220 VDC to the torch. The higher the voltage between the electrode and the cut material, the longer the arc will run without being extinguished or switched to the pilot arc mode, this assists when cutting in hard-to-reach areas, maintains the arc even when stretched for bevel cutting and gouging. The output power is not only related to the maximum current, but also to the voltage that the power supply can provide.


The duty cycle (DC) of a plasma power supply is one of the basic parameters that expresses the ratio of maximum possible cutting time to the total working time without the power supply overheating.

The EX-TRAFIRE®75SD features a massive 100% duty cycle, which makes it the flagship model not only among the Thermacut range of power supplies but even among competing power supplies. Normally an 80% duty cycle at full power equates to a top end power supply, many of the competitors power supplies fail to achieve anywhere near this value.


Thermacut power supplies are considerably lighter than competing power supplies. The EX-TRAFIRE®75SD weighs only 24 kg! Competing power supplies of a similar rated power output weigh about 32 kgs.


The EX-TRAFIRE® power supplies feature many safety elements. The most important feature is the system self-check after start-up. Inferior lower cost systems are not equipped with the same level of safety in mind.

  • Self-check after system start-up, the power supply operating software checks for system malfunctions, the power remains disconnected until the analysis is completed and safe to use.​
  • Torch safety elements also include a “Cap Sensor”. Checking for short-circuits between parts. Checking when the power supply is turned on and the torch switch is activated.


EX-TRAFIRE®75SD and 100SD offer a gouging feature. It is used for “Back Gouging” of weld seams,removal of old or defective welds. A more cost effective option compared to Air Carbon Arc Gouging.


The EX-TRAFIRE® SD series is an uncompromising professional range of plasma power supplies developed for the decerning metalwork artisan through to the trade professional. The build quality, performance and safety features outclass the cheap plasma power supplies made for occasional use but also portrayed as being suited to trade applications. Poor build quality, overheating (low duty cycle) and the lack of safety features are common issues with plasma power supplies purchased from various hobby markets, food supermarkets or less knowledgeable welding distributors. Thermacut® disassociates itself from supplying products that may endanger the well-being of the operator.

We hope you found this article useful. If you need any advice in this area, do not hesitate and contact us. You can contact at this email address:

We also recommend another related article called “Criteria for selecting a suitable power supply” and “Package content of EX-TRAFIRE® sets”.

Text:      Thermacut, k. s.,
Photo:   archive of Thermacut, k. s.