TIG Welders

Invertig 400 AC/DC

Product # 601602

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♦ Invertig 400 AC/DC Power Source ♦ Welding Cart ♦ Smart Water-Cooler ♦ 12.5' 18 Series Rigid Neck Trim Line Water-Cooled TIG Torch* ♦ 12.5' Foot Pedal* ♦ Flowmeter ♦ Gas Hose ♦ 1-Gallon of Coolant ♦ 15' Ground Cable and Clamp Assembly*

Does Not Include:
Gas Bottle, Filler Rod, Power Plug

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We designed the HTP America® Invertig 400 AC/DC for heavy use in industrial settings; applications of use include precision fabrication, motor sports and racing fabrication, pipe fabrication, aluminum fabrication, aerospace work and repair, along with work and repair in ship and rail yards. The Invertig 400 runs the following processes: TIG (GTAW), Pulsed TIG (GTAW-P), Stick (SMAW), and Pulsed Stick (SMAW-P). When connected to single-phase, 208V to 240V power, the Invertig 400 features the highest output of any welder on a 50 amp circuit—a full 350 amps of raw welding power! Additionally, the versatile Invertig 400 runs on 3-phase power from 208V to 575V, providing the full welding amperage of 4 to 400 amps. The Invertig 400 showcases a rated output of 350 amps when run on single-phase and a rated output of 400 amps, with a remarkable 100% duty cycle at 300 amps, when run on 3-phase. Planning to run this machine on single phase? Please let us know if you have less than 218 volts.

General Features

  • Automatically adjusts for input voltage: 208-240V on single-phase and 208-575V on 3-phase
  • Meters can be calibrated for certification
  • Smart water-cooler that only turns on when needed and stops the arc when it detects a low coolant level
  • The cooling fans blow directly into heat sinks and the circuit boards are protected from grinding dust and moisture by a special lacquer coating which makes the machine IP23
  • Cooling fans work on-demand; the fans only power up when cooling is required, reducing noise and eliminating unwanted grinding dust from being pulled into the machine while the machine is idling
  • This machine has High Frequency start with the option to change to Lift-Arc Start when you work around sensitive electronics where high frequency is unwanted
  • 30 memory programs allow you to save specific welding parameters for 30 different welding jobs
  • NEW -Air Carbon Arc gouging mode.  See below.

Stick Features

  • Arc-Force (DIG): Helps reduce "sticking" of the electrode
  • Hot-Start: For easy arc strikes
  • DC and AC Stick Welding: AC frequency and balance can be adjusted in Stick mode as well
  • Pulse Stick Welding: Makes bridging gaps easier, welds out of position better, and reduces heat input
  • NEW -Air Carbon Arc gouging mode. Air carbon arc gouging is a thermal cutting process of removing or severing metal by heat from a carbon arc. The process uses a carbon/graphite electrode, power source, and compressed air. The intense heat arc produced between the tip of the electrode and the metal workpiece melts and cuts the metal.

TIG Features

  • 350 amp output on 50 amp Single-Phase Circuit
  • Asymmetric AC allows you to limit Electrode Positive or Electrode Negative amperages separately, which gives you more control over heat input on critical welds
  • AC Balance: Adjustable from 10 to 90%; allows precise control of oxide removal vs. penetration
  • AC Frequency: 20Hz to 400Hz (under 100 amps) and 20Hz to 200Hz (over 100 amps); Helps reduce or enhance heat input and focus the arc
  • Three AC Waveforms: Soft Square, Square, and Triangular

*Upgrade options available, via drop down boxes above, for additional charges.

Please note: Other upgrade options may be available. Please contact Customer Service at (847) 357-0700 to discuss your upgrade options.

Warranty Information: The Invertig 400 welder (machine only) includes a 3 year warranty, the Smart water cooler has an 18 month warranty, and the TIG welding torches are warrantied for a period of 90 days against defects in material and workmanship. 


The Invertig 400 SHIPS to any business/commercial address with access to a forklift in the Contiguous United States (i.e., the lower 48) for a flat fee of $195. If you choose to ship the machine to your residence, accessorial fees will apply (a residential delivery fee, a lift-gate service fee, and possibly a limited access fee). Accessorial fees vary by ship to location and by freight carrier. You may place your order online, but you will be contacted by Customer Service to arrange and pay for any applicable accessorial fees. To avoid additional accessorial fees, we can also ship the machine to your nearest freight terminal, where the carrier will hold your machine for you to pick-up.

Also, if your ship to address is in Alaska, Guam, Hawaii, Puerto Rico, or any other U.S. Territory outside of the Contiguous United States, additional shipping charges will apply and accessorial fees may apply. You may still place your order online, but you will be contacted by Customer Service to arrange and pay for partial shipping along with any applicable accessorial fees.



Your truck freight shipment leaves our facility and is accepted by the freight carrier in good condition. The material becomes your property when signed for by the freight carrier. Our responsibility for the shipment ceases when signed for and removed from our facility by the freight carrier.

Inspect your shipment thoroughly as soon as received. If possible, unpack the shipment in the presence of the driver. If this is a "HOLD ON DOCK FOR PICK-UP" shipment, inspect the shipment prior to leaving the freight terminal. If you do not inspect the shipment for loss or damage prior to signing for and leaving the freight terminal with the shipment, then the freight carrier will claim that you damaged the shipment bringing it home. If you notice loss or damage, then you must note this on the freight bill.

We are willing to assist you in every possible manner in the collections of claims for loss or damage, but this willingness does not make us responsible for such collection of claims or replacement of materials.

Input Voltage Single-Phase: 230V (208 to 240V)
3-Phase: 200 to 575V
Welding Current Single-Phase 4 to 350A
Welding Current 3-Phase 4 to 400A
Single-Phase Rated Output 35% @ 350A
230V Single-Phase Input Amps @ Rated Load 50A
3-Phase Rated Output 30% @ 400A
3-Phase Input Amps @ Rated Load 230V = 36A
400V = 21A
460V = 17.6A
500V = 16.8A
Welding Modes Stick
TIG Spot
TIG Reset
Programmable Memories 30
Asymmetric Arc Yes
AC Frequency (Hz) 20 to 400 (Up to 100A)
20 to 200 (Over 100A)
AC Balance (%) 10 to 90
Pre-Flow (Seconds) 0.1 to 5.0
Post-Flow (Seconds) 0.1 to 99.9
Initial Amps (%) 10 to 90
Final Amps (%) 10 to 90
Slope Up (Seconds) 0.1 to 10.0
Slope Down (Seconds) 0.1 to 10.0
Spot Time (Seconds) 0.1 to 10.0
Hot Start (%) 0 to 50
Arc Force (%) 0 to 500
Wave Forms Soft Square
EN Amperage (%) 10 to 99
EP Amperage (%) 10 to 99
Duty-Cycle (Single-Phase TIG) 35% @ 350A
60% @ 250A
100% @ 200A
Duty-Cycle (3-Phase TIG) 30% @ 400A
60% @ 340A
100% @ 300A
Duty-Cycle (Single-Phase Stick) 35% @ 260A
60% @ 200A
100% @ 180A
Duty-Cycle (3-Phase Stick) 35% @ 300A
60% @ 240A
100% @ 200A
Dimensions (Length x Width x Height) 26-1/2" x 12-1/4" x 17-1/2"
Weight 121 Lbs.
Pulse Parameters
Pulses/Second (PPS) Stick AC & DC
Pulses/Second (PPS) TIG AC
Pulses/Second (PPS) TIG DC
Peak Time (%)
Background Amps (%)

0.4 to 5.0
0.4 to 10.0
0.4 to 999.9
10 to 90
10 to 90

CA Prop 65 - For Residents of California
Warning: Welding and cutting equipment, accessories, and fumes can expose you to chemicals, including Chromium (Hexavalent Compounds), Lead, and Nickel, which are known to the State of California to cause cancer and/or birth defects or other reproductive harm. For more information, please visit www.P65Warnings.ca.gov.
Customer Reviews
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United States United States

Invertig 400

Excellent machine I run this machine on 220v single phase at 280-300 amps AC Tig for hours and hours on end. It never quivers in the slightest. The machine has single handedly upped the ante in my shop. Very impressed and lifetime return customer if they can keep them in stock haha. Good job HTP

Ron B.
United States United States

Invertig 400 Evaluation

Full Disclosure: I am not a professional welder but am a huge HTP fan, already owning an Invertig 221, an Inverarc TLP, and a Pro Pulse 200 and Pro Pulse 300. I became acquainted with HTP welders, when I enrolled at the Truckee Meadows Community College in Reno, Nevada in the Welding Technologies degree program. TMCC uses Invertig 221s as the primary TIG welders, although they also have a few large Lincoln and Miller commercial TIG welders in the 350+ amperage range. So I have been able to use several different quality power sources that I can draw a comparison to. And TMCC now has an Invertig 400 for use in the advanced welding program. I purchased my Invertig 221 in October of 2014 and have used it almost weekly for the past 5+ years as part of my hobby of welding for relaxation. The 221 is a great welder with no limitations other than the higher amperage. So when the 400 came out, I knew I just had to have one. The difference between the 221 and the 400 is the difference between "great" and "fabulous". What makes that difference, besides the added horse power are several subtle things. The first is the "big picture" ease of operation and setting changes. The 400 front panel screen shows every setting in one simple to understand picture. Changes are then just a one or two switch operation, that are also immediately visible on the screen. That screen is magic!! The next difference is how quietly it runs with the dedicated "on demand" cooler designed to work with the welder. I didn't realize how much that "quiet operation" could mean, but I am now hooked. And finally, of course, are the additional modes, along with spectacular arc dynamics and the different wave forms and added setting options. All this, coupled with the added amperage capability, put this welder in a class with just a handful of other well-known commercial welders, all of which are more expensive. I have used the 400 since January, and have about 250 hours on it. I tried stick welding with it, and was impressed, although as great as it is, nothing can compare to the Inverarc TLP when it comes to pure SMAW/Stick welding smoothness and pleasure. So I use the 400 exclusively for AC and DC TIG welding. I will definitely keep my 221 as a backup welder, especially since I can use it with 110 volts for lower amperage applications when 220 volt power is not available. But the 400 has become my absolute "Go To" welder when it comes to TIG welding. As I disclosed, I am not a professional welder. I am a retiree, who took up welding about 12 years ago as a hobby rather than golf. It is just as frustrating and probably as expensive. As such I weld almost every day, just for fun. So if any potential customer wants any added honest feedback feel free to give them my contact information. HTP can well be proud of the Invertig 400.

United States United States

You. Need. This. TIG. Period.

Very happy with this TIG as it has all the power I will ever need. As soon as you plug it in and turn it on, it's always in BEAST MODE, as it has HP to spare! But the low-end is something to behold as well. The arc performance is crazy good. With the right taper grind/sharpening on a 5/32" Ce tungsten, and with just the right amount of user-adjustable hot-start, it can maintain a stable arc down to 4 amps. Yes, a 5/32" Ceriated tungsten on this TIG can maintain a stable arc down to 4 amps ! Check out my video on YouTube on this machine if you want to see all the menus and features and functions. The on-demand Smart-Cooler is great because it's whisper quiet and only runs when needed. Nothing in this price range can touch this welder/cooler/cart combo. As a stick welder, it is ****** good. Plenty of power to run all but those 3/4" diameter electrodes! The adjustable pulse function and AC gives it that nice edge. With pulse, you can run a 5/32" 6011 to weld 14 gauge material. I did this on my Inverarc 200 TLP, but this machine would also be capable of that same exact feat. And of course, you can use a slider control when you're stick welding (or TIG of course) to control the heat on-the-fly, or even a wireless footpedal.

United States United States

HTP Invertig 400

I absolutely love this machine! I wasn't happy with the duty cycle and arc starts on my Miller Dynasty 300dx and I wanted the extra features for AC welding that my Lincoln Precision TIG didn't have. Not 100% happy with either welder, so I decided to go shopping. I looked at new Millers, WAY too overpriced and Lincoln only had one inverter to offer, Everlast, well lets just say I couldn't bring myself to purchase a made in China welder. I ended up with the HTP Invertig 400. Not overpriced, amazing arc stability (SUPER SMOOTH) and arc starting compared to my Dynasty, made in Italy, excellent customer support compared to the other brands and HUGE duty cycle on this machine, 100% @ 300amps! I never have to give it a break, I just weld all I want. This machine runs super quiet and only uses the fan speed that it needs to keep the noise to a minimum. It idles silently. The invertig 400 welded super nice with zero adjustments, right out of the box. I immediately sold the Miller dynasty and sold my Lincoln precision tig as well. My next 2 welders I plan to purchase will be HTP as well. Hands down the best welder I have ever used.

HTP America - USA Weld Invertig 400 AC/DC ReviewHTP America - USA Weld Invertig 400 AC/DC ReviewHTP America - USA Weld Invertig 400 AC/DC ReviewHTP America - USA Weld Invertig 400 AC/DC ReviewHTP America - USA Weld Invertig 400 AC/DC Review
Scott M.
United States United States

Best Tig Welder I’ve ever used in 36 years.

I started my welding shop in 1984. In the last 36 I’ve owned/used 10 different Tig welders. Blue & the other Ted brand. None of those tig machines were as capable as the HTP Invertig 400. The soft starting arc is awesome!!! At idle the machine is very quiet. Amperage control is better than any Miller Dynasty I’ve ever owned. When I decided I needed a great Tig machine I looked Miller,Lincoln,HTP, Everlast. Everlast was priced lower but after reviewing their FB page I found about 2in 10 had real problems with the machine within months of buying it. The Miller Dynasty 400 was 11k with tax. Lincoln didn’t have anything that interested me. The HTP 400 was priced right and seemed to have good customer satisfaction. So after taking with Peter Zila I decided on the HTP. Best welder I’ve ever bought in 36 years of business. And I’ve owned over 50 machines. I guarantee you won’t be disappointed in your purchase of any HTP welder. Thanks Scott Mock Owner of Chubbys Welding & Machine. Since 1984.

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