Synchro 250 keeps blowing breaker

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My Synchrowave 250 is plugged into a 50 amp circuit.  The most I've cranked it up to is 150 amps AC.  The funny thing is that the breaker never blows under load.  It will trip while the fan is running and I'm not welding with it.  It has blown with the machine dialed at 100 amps also.The prior owner, who was it's original, states he never ran it over 100 amps.  I can't see him dealing with the breaker blowing all the time.  He had it plugged into a 50 amp circuit as well.  I'm thinking I have a bad breaker, but am I expecting something unrealistic from this machine on  a 50 amp circuit?Last edited by Drf255; 07-24-2011 at 09:50 PM.
Reply:Check over the wiring for insulation chafing and a short.   Shorts trip breakers, quickly.  Something that is not always in contact will do that when conditions are right.Otherwise, sure, swap the breaker.  They are cheap.-DaveXMT304 with: 22A Feeder, or HF251 Hi Freq DC TIG air cooled
Reply:Does your fan run continuously or is it fan on demand? If it does not run all the time that is where I would start. Otherwise I would take the plugs apart and start there.Millermatic 252millermatic 175miller 300 Thunderboltlincoln ranger 250smith torcheslots of bfh'sIf it dont fit get a bigger hammer
Reply:You really need a 100 amp service...50a wont cut it for the 250.
Reply:Originally Posted by SR20steveYou really need a 100 amp service...50a wont cut it for the 250.
Reply:Originally Posted by farmshopDoes your fan run continuously or is it fan on demand? If it does not run all the time that is where I would start. Otherwise I would take the plugs apart and start there.
Reply:The manual says that at 230 volts and 60% duty cycle, the machine should draw 76A and 48A with "power correction factor".  It states a 4A draw at idle.  200 amps is 60% duty cycle.  What the hell is "power correction factor"?I'm not pushing the machine anywhere near it's limit, but I don't know if the input/output amps change on a linear fashion or not.  My house is only wired for single phase 200 amps.  The central air alone draws 120 amps when both compressors and evaporators are on, so if I put a 100 amp service I may overwhelm my panel in the summer.  My breaker panel is around 70' from my garage.  The cost of the wire to run the new circuit and all the goodies will easily cost me more that $500.   Again, the elephant in the room is that the breaker blows under no load.  That's what makes no sense.  If this is going to be this big of a problem, I may consider selling the machine and upgrading to a Dynasty 200.  I will probably get $1700 for my machine (what I paid).  So with the electric added in, and the price of $3000 I see for the dynasty, I'm only looking at around $800 more.This sucks.
Reply:Do you have a 50A breaker that you KNOW is good that you could swap out and put on the circuit you now have wired for the Sync250, so that you can "rule out" that you simply have a bad/weak breaker?I always start with the simplest solution and work back...
Reply:I think my machine has power factor correction (PFC).  As per the manual, it consumes 51 amps at idle!A no PFC machine consumes 4 amps at idle.  It appears that PFC is made to keep voltage constant and reduce energy consumption with machines used over 155 amps almost continually.  It draws all these amps to keep capacitors charged.   Then I probably got voltage drop to my house cause of the crazy hot weather here. So the amp requirement went up even further.  So in theory, my machine draws more amps at idle than when welding at 150 amps.  Completely defies logic. Does anyone know how to remove or disable this device?Last edited by Drf255; 07-25-2011 at 07:18 AM.
Reply:You're going to need to get the service bulletin or installation docs on the correction capacitor kit and remove it.The biggest thing they do is keep the transformer from dropping cycles when welding AC over 150amps and running unbalanced output. After removing them it is hard on the lump to run 10 on the balance dial north of 180amps.The effect of changing the load from resistive to neutral helps if you have a demand power meter but that is rare with residential power.Matt
Reply:I highly doubt that your Syncrowave 250 is drawing anywhere near 51 amps at idle. And, switching machines is really not going to fix your under powered welding circuit in the garage.If I were in your shoes and lacking the tools needed to correctly diagnose the problem I would start making some calls. Surely you must know someone with a Volt/Ohmeter, and a  induction current probe (to measure the current draw at idle and load) that knows how to use them. Sorry if I seem to be talking down to you. I'm not. But, you can't begin to solve this problem without first isolating and ruling out certain causes.BTW, both of those pieces of basic electrical test equipment are available for not too much at your local home improvement center. If you're planning on doing this welding thing for awhile and maybe doing some basic upgrades on your garage electrical they would be a good investment. Not too difficult to use them really.You've had this welder for a couple of weeks now right? Has it been tripping the breaker all along?Your first post in this thread says that the previous owner had it hooked up the same way but did not have the same issues so its doubtful that PCF is the cause here.I bet you're going to find an intermittent short somewhere in the 50A circuit. Eric
Reply:It actually does draw 50 amps at idle with the PFC. I know it makes no sense.  My brother is an electrician and I will have him test the circuit.
Reply:I wouldn't go selling your machine yet.  I have a sync 250 w/ a PFC on a DEDICATED 50a circuit and only blew the breaker when the on/off switch was going out (must have been a short in it).  I've NEVER blown it under load or just sitting at idle.Millermatic 135Syncrowave 250
Reply:Power factor refers to how much energy is reflected back into the 230v line instead of being actually used. In a purely resistive load, current and voltage are in phase with each other, in reactive loads however, such as transformers, they are out of phase and and the apparent power (VA) will be greater than the real power (Watts). Poor power factors therefore draw larger currents from the line to do the same work. You machine will draw 76amps, or only 48amps to do the same amount of work if the power factor is corrected to whatever degree.Inverter welders have very good power factors because the input stage is typically a power factor correction stage. This lets them weld at 200amps off say a 30amp 230v breaker.And there is absolutely no way your machine draws 51 amps at idle lol, thats like 11kw of heat that would have to be going somewhere (that's as much heat as three 1/8" stick welding rods would use).Last edited by MikeGyver; 07-25-2011 at 07:51 PM.Welding/Fab Pics: www.UtahWeld.com
Reply:PFC was the problem.  The miller people are great.  The tech walked me through disconnecting it and making a schematic of how to reconnect when I increased my line amperage.  Let the machine idle for over an hour today.  TIG'd steel, stick welded at 150 dcen and dcep, and ran around 6 feet of bead on 3/16" Aluminum at 175 amp max with no problems whatsoever.
Reply:Hm, you should see how many amps you can pull max w/o the PFC.  I'd be curious to know.Millermatic 135Syncrowave 250
Reply:Yes PFC draws 50 amps, I have a syncro 250 too. Draws 4 amps without PFC. Wide open without PFC will draw 92 amps, mine is on 100 amp slow blow fuses.PeterEquipment:2  old paws2  eyes (that don't look so good)1  bad back
Reply:Originally Posted by castweldYes PFC draws 50 amps, I have a syncro 250 too. Draws 4 amps without PFC. Wide open without PFC will draw 92 amps, mine is on 100 amp slow blow fuses.Peter
Reply:First off, I want to sincerely thank everyone for their help.  When I spoke to the Miller tech, he said that the capacitors continually charge and then dump some charge back into the line.  He said that the PFC actually pulls 50 A at idle, but does actually use much electricity.  It reduces the amps needed at 60% duty cycle at 230V from somewhere near 76 to 48A.   McGywver seems to understand how this works.  Now that it works disconnected, I'm thinking of adding a switch in one lead of the 2 wires leading to the PFC capacitors.  That way if I ever have to do some welding at 175 or need to use the machine in my friends shop with a 50A circuit, I can.  I also am gonna try to source the necessary wire needed to just run the right 100 amp circuit.
Reply:If its pulling 50A at idle that's 50A of current flow. That's what your KW/Hour Meter measures and what you're paying for every month. Current flow is use. It doesn't go back into the power grid (like a generator or other home owner created power source). So its demand on the line.I still don't see how this is either practical or even responsible use of energy.Perhaps I'm being obtuse about this and need to some of my own research about it. Glad the problem is solved for you.E
Reply:Originally Posted by Welding_SwedeIf its pulling 50A at idle that's 50A of current flow. That's what your KW/Hour Meter measures and what you're paying for every month. Current flow is use. It doesn't go back into the power grid (like a generator or other home owner created power source). So its demand on the line.I still don't see how this is either practical or even responsible use of energy.Perhaps I'm being obtuse about this and need to some of my own research about it. Glad the problem is solved for you.E
Reply:Originally Posted by Drf255First off, I want to sincerely thank everyone for their help.  When I spoke to the Miller tech, he said that the capacitors continually charge and then dump some charge back into the line.  He said that the PFC actually pulls 50 A at idle, but does [not (sic)] actually use much electricity.  It reduces the amps needed at 60% duty cycle at 230V from somewhere near 76 to 48A.   McGywver seems to understand how this works.  Now that it works disconnected, I'm thinking of adding a switch in one lead of the 2 wires leading to the PFC capacitors.  That way if I ever have to do some welding at 175 or need to use the machine in my friends shop with a 50A circuit, I can.  I also am gonna try to source the necessary wire needed to just run the right 100 amp circuit.
Reply:Thanks for the info. I do have some reading to do. Good explanations by the way. I guess I don't know as much about AC systems as I thought I did.Time to fix that. Eric
Reply:It could be the breaker is bad. I do electrical work and have replaced plenty of breakers that do this. They tend go bad in garages or barns where they get temperature changes. I have a hobart mig, tig, stick machine about the same size. It needs a 100amp breaker but it is on a 30 amp breaker and never trips it but it trips the 60 amp main randomly and but never does it during a weld.