Mosfet vs IGBT Technology Plasma Cutters

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Ok folks since Aug 08 I have been thru four (4) plasma cutters. (Yes they were Chinese made)1st was a 50amp it failed on its highest setting.2nd was three 80 amp units. Two of which failed at their highest setting of 80 amp and the third failed at half full power (40amp).In all of the units the mosfet retention bar screws were overtorqued.In all of the units the mosfets blew out or exploded.Folks have recommended going with the newer IGBT technolgy which apparently can handle amp & temp requirements of the higher amp plasma cutters.From what I have seen on the high amp inverter plasma cutters they are capable of some impressive cuts. Yep one of the three 80 ampm units did make it to its fourth use before its fireworks display. That unit did an impressive 1.25 inch cut thru hardened alloy dragster  axle. Of course that unit also failed when its mosfets exploded.Question: Is there a lower cost plasma cutter that uses both Inverter and IGBT Technology?Co-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:I got a really nice unit from Everlast its Called Super200pi using german IGBT'sthe unit pictured on his main webpage in the upperleft hand cornor.I just got it a few days ago, its a multi function unit. 200amp ac/dc tig with pulse 160amp stick 50amp plasma... Iam still in the process of hooking it all up and getting things laid out.here are a few pics: Attached Images
Reply:Your right nice looking unit. Sure hope it came with a good manual to be able to figure out all those dials,  settings, and hookups.Well its nice to see that someone is having luck. Looks like a nice unit sure hope its got a good manual for all those dials and hookups.Over three months I have had 4 units so in a way I had 4 in 1 machines (Oooooooooooooh bad pun) Being a disabled vet on fixed income I thought I would save some money. But so far it just hasn't worked out for me. Its been 3 months of shipping units, paying to have them wired and unwired, watching them throw a fireworks display, and of course not having a working unit. I may end up following folks advice and give up on the mosfet equipped units. Our Local Airgas dealer also a member of weldingweb (small world) has seen my situation here. Their site www.airgas.com as well as their product guide list some good deals Hypertherm Powermax 30 $1,159, Hypertherm Powermax 600 $1,419, ThermalDynamics Cutmaster True 39 $1,169, ThermalDynamics Cutmaster 52 $1,539, Miller Spectrum 375 Extreme $1,299, and Miller Spectrum 625 $1,799. Airgas even offered me 10% off for all I have been thru trying to get a personal use plasma cutter.But my questions to you is!Is IGBT much better than Mosfet? Do Hypertherm, ThermalDynamics, and Miller all use IGBT?As 3lusive240 said above his new (chinese) unit does have German IGBT's versus Mosfets.  But after all that time and money I spent on those 4 units I am not sure I really want to try another  Chinese made unit.As I have said above: Question: Is there a lower cost plasma cutter that uses both the benefits of Inverter and IGBT Technology?Co-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:I spoke to other folks out there that have had outstanding performance of their units. The one unit I  had received that made it to four uses was truely impressive for the price. & cutting abilities  But like many said at what point to you cut your losses and look elsewhere?Last edited by specter; 11-05-2008 at 10:28 AM.Reason: typo correctionCo-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:I would think the odds would be pretty slim on getting 3 failures shipped to the same person without some other type of trend being visible in all the other units shipped.I wonder how many people have these that we never see since they are not on the weldingweb.Have a nice dayhttp://www.weldingdata.com/
Reply:Your certainly right in questioning the four (4) failures and odds of that happening to one person. Out of the total four units one was a 50 amp unit and the three others were 80 amp units. The 50 was from one manufacturer and the 80's from another manufacturer. If you look at the pictures of the units in my posts you'll see the designs of both manufacturers were the same. The first three units were used at one location and the last unit was used at another. In each case they properly hooked up by a licensed electrician. In the first three units I had the help of a cnc shop tech as well. In  each case both manufacturers were contacted , the situations/symptoms explained and  another testing of the unit tried after walking thru complete hookup, grounding, checking connections and air pressure. In each case the units still failed. I even went so far to test my Lincoln ac 225 on the same electrical circuit to make sure it wasn't the circuit! In each case my Lincoln performed. The electricians in each case tested for proper grounding, electric current & amperage, etc. In each case the failures occurred on the top circuit board of each unit and were documented by pictures. I am not out to ripoff anyone. I do not know who's fault it was design or otherwise. I am trying to be fair & just in my evaluation and documentation of the incidents.I just want product that works.Last edited by specter; 11-05-2008 at 11:52 AM.Reason: correction of transposed sentenceCo-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:In regards to reliability....and I can only speak for Hypertherm as I have worked there for over 30 years....we switched to IGBT switching technology on both our inverter based plasma's (as used for air plasma systems....Hypertherm's Powermax units) and our Chopper based units (mechanized high power industrial Hyperformance plasma's) not for lower manufacturing cost....but for performance interms of better long term reliability as well as better output power control.The reliability part is very important from (most) manufacturers points of view as it reduces warranty costs....and makes our end user customers happier....and hopefully when the need arises they will come back for their next plasma system purchase.Better performance is critical to consumable life. We use a microprocessor to control output power which includes accurately controlled ramp-up and ramp-down of current....as well as accurate timing of the gas flow on/of cycles. With IGBT switching rates we can control this function (that is necessary to increase consumble life) much more accurately than with our old FET (MOSFET) systems (anyone remember the early Hypertherm inverters...the Max41, 42 and 43?)As far as costs of the systems go.....excellent power supply design, testing and manufacturing here in America is not inexpensive. While we at Hypertherm have a state of the art manufacturing facility....and I invite anyone for a tour of the factory...we do not have the lowest price plasma cutter out there. However...if you use the plasma system for production work, we in most cases have a system that provides the lowest operating cost.....and highest reliability.Operating cost is a function of all of the costs of a system, initial purchase price, cost of consumables, cost of electricity, cost of air, cost of maintenance, and cost of downtime all factored over the useable life of the product. The more you use a more reliable product with lower operating cost....the less expensive it is.I agree that there are many applications where a very low cost plasma (purchase price) that may not be as reliable....or as iexpensive to operate may be an acceptable (or the only) choice.If you can....go to your local welding supply stores and ask them if you can cut with a major brand (higher purchase cost) plasma.....then try out the low purchase price systems. If cut quality is acceptable.....duty cycle is acceptable....and consumable life is acceptable...then the choice is easy. If it is long term performance, parts and service availability for many years.....and low operating cost that you want....often you have to pay more up front.Jim Colt
Reply:Originally Posted by 3lusive240I got a really nice unit from Everlast its Called Super200pi using german IGBT'sthe unit pictured on his main webpage in the upperleft hand cornor.I just got it a few days ago, its a multi function unit. 200amp ac/dc tig with pulse 160amp stick 50amp plasma... Iam still in the process of hooking it all up and getting things laid out.here are a few pics:
Reply:Spoke with manufacturers customer service. He emailed me a prepaid DHL shipping label along with the following Longevity Affidavit regarding condition of the unit at time of shipping. I added a note to the addidavitDear Longevity:I, (Name) ____________________________the purchaser in regards to the Longevity plasma cutter/welder order am returning the unit: _____80amp plasma cutter __________. I am asking Longevity to ship back the unit under their return policy. The unit was not damaged at the time of delivery and is being returned in original condition with outer casing and all internal components properly attached. I am asking Longevity to ship the unit back for me. Although I understand this affidavit was prepared by Longevity, by signing this form, I certify these statements to be true.Sorry for the troubles.Thank You,(Name):(Signature):Please provide copy of your driver license and fax back to 1-510-887-7091Note: Unit is being returned as non functional. The main upper circuit board was damaged upon powering up the unit and is being returned per warranty return policy.And a full refund issued.Consider me paranoid but after all these problems I just wanted to protect myself since that is a signed affidavit. Oh I did not include a copy of my drivers license. add on Strange they never asked me to sign this addidavit when I returned the two previous defective unitsDHL will be picking up the unit tommorrow.I haven't returned anything in years I guess this is what it has come to for manufacturers we request a refund from??!!Last edited by specter; 11-05-2008 at 08:59 PM.Reason: add onCo-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:I went through FOUR 160 T's. First three failed at startup.  Fourth lasted 2 days. Then I traded for a stand alone plazarc ant a Cut 50 (DC tig welder).the tig has worked well several times.  This is what happ0ened the forth time I used the Cut 50. Attached ImagesA butterfly without wings, is just an ugly bug
Reply:WOW!!! Sure sounds and looks alot like what I am going thru. I also had problems with the Cut50 plasma cutter(besides the unit not having the digital meter the ebay said it was supose to have). Looks like you had worse problems. Amazing the damage in your pics is about the same as my pics. Looks like you had some great fireworks as well. Hopefully you didn't have anything flamable near that  when it happened. Did they make you sign an affidavit as well when you returned the units?What did you finally end up with? did you stay with mosfet technology or step up to IGBT?Last edited by specter; 11-05-2008 at 10:37 PM.Co-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:All the customer service in the world will only go so far if you have 4 machines to send back. Even for a hobby type welding that would be a trying experience.Have a nice dayhttp://www.weldingdata.com/
Reply:Get yourself a Hyperthem PowerMax 30 or 45. You will not be disapointed. I bought a used Powermax 30 and have already used it a bunch, 110 or 220 volt (it works great on both). I have not had one problem with my machine yet, works every time. -DanOwnerDW Metalworks LLCMiller Trailblazer 302Miller 8RC FeederMiller Passport PlusMiller Dynasty 200 DX W/Coolmate 1Hobart Handler 135Hypertherm PowerMAX 30Smith O/A Torch SetPlus much much more
Reply:Originally Posted by Miller article on inverters"With semiconductors, the secret to a long life is to reduce their operating temperature. There is an equation which basically states that every 10 C temperature increase cuts an IGBT's life in half."
Reply:What Digital meter?More like a lightning bolt than fireworks. The only flamable  thing nearby was me.This just happened at 3:00 Yesterday, so I don't know the outcome yet.A butterfly without wings, is just an ugly bug
Reply:Originally Posted by gaustinAll the customer service in the world will only go so far if you have 4 machines to send back. Even for a hobby type welding that would be a trying experience.
Reply:Originally Posted by engnerdanGet yourself a Hyperthem PowerMax 30 or 45. You will not be disapointed. I bought a used Powermax 30 and have already used it a bunch, 110 or 220 volt (it works great on both). I have not had one problem with my machine yet, works every time. -Dan
Reply:Hi Dan, Dave & HephaestusThis purchase experience has been a eye opening experience for me. Our cnc shop in NY has only bought brand name products that have been long established on the maket.This was my 1st non brand name purchase.I have never gotten into the actual components within the equipment I have left that part to the experts. But I am certainly learning by trial by fire. The units I have been buying are for my own private use on my farm. Watching the electrician wire the plug and the cnc shop tech walk thru testing the defective units with the  two different manufacturers customer service has taught me alot.Don't know what I am going to buy this time. One of the two manufacturers is planning to get a bunch of new IGBT units (of course Higher priced). Our cnc shop up in NY has an account with Airgas and right now they are selling the hypertherm powermax 30 at $1,119 or the 600 at $1,400. ands even less if bought thru them online. I was hopeful someone on welding web might know of a good deal out there.Like you said magnetic I too already paid for the unit. When you consider the initial cost, the electrician,  cnc techician help and the time going back and forth those four (4) cuts that I finally made cost me well over the cost over the on sale hypertherm's at airgas. I figure that was about $325 -$400 per cut.Either way I plan to stick with brand name such as hypertherm, thermal dynamics or miller! I am afraid my taste for Chinese has come back home to America.add on: You now something MagneticMan I read somewhere in one of the many posts here on welding web a couple of folks were sent units if they provided an evaluation here on weldingweb. I am pretty sure no one would give me one to try out with my luck but you might wannt to give it a try.TomLast edited by specter; 11-06-2008 at 12:08 PM.Reason: add onCo-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:I don't think anyone would want me to post an evaluation on these machines.A butterfly without wings, is just an ugly bug
Reply:Yeah I am pretty sure they wouldn't want me either since I give a truely honest opinion and do not butter up the opinion trying to get anything free. But Then if thhey have a great product they shouldn't have to give away anything. The product will sell itself.addon: Oh yeah DHL picked up the defective unit and it being sent back with their signed affidavit. Now its just sit back and wait for refund.I hope that you finally got a working unit or your refund magneticmanLast edited by specter; 11-06-2008 at 03:38 PM.Reason: addonCo-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:While I agree that if you buy and pay for something it should work as advertised, but my question is this as someone who just ordered an Everlast Cut50. Has anybody looked into drop-in replacements for the onboard Mosfets that are higher quality than originals, of a higher rating, and then re-doing the heat sink arrangement to more appropriate specs?It was a toss-up for me between a good Miller and the Cut50, I went with the Chinese because it leaves a little more head-room for a nice name-brand TIG, but also because I don't mind tinkering and fixing electronics when I'm not using it in a production environment.I guess I should do a little homework tonight.
Reply:Hi Ya chicksdigwagons,You may want to suggest that to Alex. I too had brought from everlast but it didn't work out for me. My posts are in that forum.I am not sure if its a design problem, circuit board problem, component problem or just lesser quality mosfets. But once the manufacturers work out the bugs (kind of like microsoft with every new software released) I think theyy may have a good product.Co-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:I agree that the quality seems to be getting better with each generation.  If you retro your mosfets and it doesn't work, what happened to your warranty?A butterfly without wings, is just an ugly bug
Reply:I would ask the manufacturer before you open the unit and try any modifications. Most stuff manufactured today always seems to have in the fine print about opening the unit voids the warranty. When I was having problems with those units I always called customer service 1st. They were pretty good about you opening the unit and looking for a loose wire or obvious visible damage!! But I can''t imagine they would let you modifiy a unit without their consent or without using their own modified parts, components or boards.Co-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:Well don't Quote me Quoting Alex, but he has said in other posts that they encourage people making enhancements to their machines. However, I'm sure the warranty goes out the window. For some folk half the hobby is working on the tools. Obviously not people who need that tool for a living. Just got word that my Everlast unit arrived today, I won't be back home for another three weeks or so but I'll take a look at it. I'm not too concerned about the warranty on a $400 plasma cutter that I can most likely repair or replace anything that goes bad inside cheaply.But if they have a reasonably low return rate, they won't bother with increased costs of adding higher quality components. I'm sure these are cookie-cutter machines anyway, not custom built to re-seller specs - despite what they might lead you to believe.I have to agree with you on the cookiecutter machines. Especially after having both a Everlast and a Longevity plasma cutte. Also someone has just posted some pics of the Everlast 80 amp and if you compare tthose pics to the pics of the Longevity 80 amp they look identical with the exception of the different colored outter cases.Co-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:Originally Posted by specteradd on: You now something MagneticMan I read somewhere in one of the many posts here on welding web a couple of folks were sent units if they provided an evaluation here on weldingweb. I am pretty sure no one would give me one to try out with my luck but you might wannt to give it a try.Tom
Reply:Hi Brett, my comment was not directed at you. It was merely a comparison of the two units  I have had both manufacturers products.! But in my previous comparison I could only compare the Everlast CUT50D to the Longevity LP-80 each from different companies. Granted not an equal comparison cause one is a 50 amp unit and the other is an 80 amp unit. Gadget (dan) has posted about his  Longevity LP-80 and to date he hasn't had a problem. I posted about the problems I have had with the  Longevity LP-80. After three units I decided to give up and get a refund. My observation of the Everlast and Longevity units was only a comparison of the photos of the circuitry that both you and I posted. Others in this forum have suggested that both manufacturers get their components from the same factory. I cannot comment on that as I have not compared the components except from what is visual in the photos we both posted. A couple of other members have also posted pics of what appears to be the same problems I was having with the LP-80 but in their case it was another type of combined machine. Since I no longer have the LP-80 both you and I cannot compare pics of components,I am not sure what exactly caused the failure in any of those units. No offense was meant to you it was merely a comparison of two units each from separate manufacturers. Prehaps both you and Gadget could get toggether and campare both units and their performance.All I want at this point all I want to do is forget this ever happen and go obtain a working plasma cutter.TomCo-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:No offense taken, Tom. Before I come to a final verdict on the Everlast LG-80E, it's going to get a LOT more cutting time on it.I do wonder about the Over Current light on these units. If the little light comes on while you are cutting, but does not have a timer and relay to keep it on after the cut, it would seem to be useless. It's kinda hard to make a cut and watch the little light all at the same time! BretRanger 250 * Invertec V205-T * Invertec V275-S * Precision Tig 225 * Power Mig 300 w/ Python Push/Pull Pro-Cut 25 Plasma * Millermatic 150 * Hobart Handler 175 * Bernard 3060 Tig Cooler Everlast LG-80E Plasma Cutter * Henrob 2000
Reply:Hi Brett, ThanksI am glad someone is having luck cause I was beginning to wonder if it was just me. Like you I did a 1.25" cut in steel and was impressed. I did my cut on round stock and my hand was shakey that day. ( I had just taken my MS shot and it sometimes makes me sick with the chills). I felt like if the unit had not blown the circuit board and mosfet it could have cut much thicker stuff.Right now I am just looking around for a cutter. It might not get much use down here but once it gets to my farm it will see alot of action. Most of the work is an average 5/8-3/4" with a max of up to 1 1/4" occassionally.I have my eyes out for a Thhermal Dynamics Cutmaster 82 or a Hypertherm 81 of course when I was looking at the units online Billy Joels "UPTOWN Girl was playing! I wonder if someone up or down there is trying to say those a a bit upscale for me.Co-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:i maintain plasma CNC cutters in  firm. and we have 5 machines and every machine has two plasma troches. each torch can handle up to 600A @ 180V an we can cut 140mm thich chrome plates. for 600A we use two uits in parallel and each unit has two IGBT's and form experience i can tell you that IGBT's are very good but they also fail. If they are pushed near their limit (150A each in our case) they fail in about 1000 hours (our machines work 24/7).But one of the machines is different form the others. it's 20 years old and we never had to open the power supply unit (except for servicing the cooling fans). this machin uses good old thyristors for power control. Thyristors are very rugged and can't fail as easy as IGBT's or MOSFET's