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Need help understanding 120v auxiliary circuit in a Syncrowave 300 welder

Vernon Tuck

Stainless
Joined
Oct 26, 2008
Location
Brenham, Texas
Guys,

I am trying to finalize a new wiring installation of an old 1980 vintage Syncrowave 300 welder. I bought the machine at a Pratt & Whitney auction. It was last run on 460V single phase. It has a 100 amp Cutler Hammer fuse box mounted on the back. I believe it was a 3 phase fuse box originally, as there are places for three fuses, although one of the spaces was empty.

To be clear, this is a single phase welder. I think there were some 3 phase Syncrowaves but this is not one of 'em. It can run on multiple voltages but they're all single phase.

The welder has a duplex 120V 10 amp grounded outlet on the lower front panel. I've been studying the literature, including schematics, and apparently there is a transformer inside there somewhere. Presumably, it drops the supply voltage (which can be jumpered to run off of 208, 230, 460, or 575 volts) to 120 volts.

The cord that runs from the power supply to the fuse box and from the fuse box into the machine, has four conductors. However, only three of these are in use: 2 hots (black and red) and a ground (green). The fourth conductor is taped up.

My understanding is that on a 120V circuit a ground may be "optional" but that a neutral and one hot are the essence of such a circuit. The owner's manual is not very helpful. What I'm trying to figure out is whether the machine is supposed to be wired with a neutral to supply the duplex 120V auxiliary plug. I cannot imagine Pratt & Whitney not wiring the machine exactly right. And all they have wired in is two hots and a ground.

By the way, I am only ASSUMING that the fuse box is a 3 phase box because of the three fuse places. As I said, the white conductor that comes into the fuse box is taped off. I am also under the impression that a neutral or a ground are never fused or broken. Hence, I conclude that the white/neutral is not intended to connect to a fused connection.

Do any of y'all have any guidance? I should also say I'm only ASSUMING the 120V duplex outlet is AC and not DC and I'm ASSUMING that it has not been disconnected. The old Lincoln SA200 engine driven welders have 120V DC outlets but I cannot imagine these are anything but AC.

So, my silly question for the day (and possibly good for the whole week) is: Is there some way to "create" an artificial neutral with a transformer? I'm assuming the answer is "no". Yes?

Thanks,

Vern
 
Vern, I looked up on Miller's site, and this is the PDF for the synchrowave 300
http://www.millerwelds.com/om/o350p_mil.pdf

On PDF page 27 (paper document page 21) you can see the 115V power circuit perpendicular to the tap side of the main transformer (left side of page if you are looking at in landscape view)

I looked around to see if "POWER PL" means power plug, couldn't confirm, but i don't see any other 115V circuits in the diagrams)

does the duplex connector even have a ground on it ?

My guess based on the schematics offered by Miller that it is just a hot/neutral two blade duplex connector.

here was a thread I found on a welding forum that talks about how normally for single phase 460V equipment, they just hook up two of the hot legs from 460-480V 3phase.
460v single phase ?

I think that explains your two lines and ground going into the machine.

Cheers!
 
Vern, I looked up on Miller's site, and... <snip> but i don't see any other 115V circuits in the diagrams)

does the duplex connector even have a ground on it ?

My guess based on the schematics offered by Miller that it is just a hot/neutral two blade duplex connector.

here was a thread I found on a welding forum that talks about how normally for single phase 460V equipment, they just hook up two of the hot legs from 460-480V 3phase.
460v single phase ?

I think that explains your two lines and ground going into the machine.

Cheers!

Nostalgic
Thanks for going to that trouble. I read the 460V "single phase" discussion and it was helpful.

Unfortunately, I have almost no experience with 3 phase, and absolutely no experience with electric circuits, single OR 3 phase, in an industrial setting, which this machine came out of, for sure. My ceiling on my skill set is the knowledge and experience I've acquiredfrom installing several residential single phase service entrance and sub panels and circuits.

That discussion DID cause me to wonder if the original 460V service was two legs of a 3 phase service plus a NEUTRAL and NOT A GROUND. All I can report is, that what I'm calling the "ground" conductor is green and that it connects to a lug on the frame of the transformer. In my limited experience with 3 phase machines I've acquired, I've learned that in the 3 phase world the color codes I associate with wiring mean little or nothing.

The machine DOES have a separate ground lug on the sheet metal on one side. This caused me to wonder if my SINGLE PHASE NEUTRAL should go to the transformer frame and the ground to the frame of the machine. However, way down deep this doesn't seem right. And, right or wrong, I'm not the sort of guy who will just "see if it works" where electricity is concerned. In my admittedly limited experience, a 115V circuit is always "a hot and a neutral". A 230V circuit is always "2 hots and a ground". And finally, "the neutral and the ground "shall meet nowhere except at the main service entrance". That has been my mantra for as long as I've been working on our own wiring.

So, my choices are to keep needling y'all and/or try to reach a Miller tech support guy on Monday.

I genuinely appreciate your interest in this.

P.S. To answer your question: The 115V duplex outlet is in the lower front cover underneath a swing down "door" on the RIGHT side. It is a 3 prong duplex outlet i.e. what I would think of as "a hot, a neutral, and a ground". It has a warning label saying not to exceed 10 amps of load.

V
 
Code has changed through the years, especially the treatment of "neutral" and "ground" wires.

Used to be you could detect the "hot" side of a duplex receptacle by inserting a neon tester or a voltmeter between the assumed hot and the ground, such as a metal conduit or metal electrical box.

You still can attempt it; if a GFCI is involved, you will trip the GFCI. And it used to be that the switched and unswitched receptacles on the back of stereo equipment had no ground prong facility, as recently as the 70's - 80's .... Technology marches on :)

In this specific situation (which involves you), let's ignore theory (and any more history lessons) and go right to implementation. You want a 120 duplex receptacle on this unit, and you will be supplying 240 volts, correct?

Will the unit be hard wired, or will be you using a 120/240 50 amp range receptacle? (Yes, I have limited your options, sorry about that :) )

Either of the two hook-up options can provide a neutral; in a hard-wire situation, just drag in a white neutral and a green ground, and a late-model (code changes, again) range plug will have four blades, two for the hots, one for the neutral, one for the ground.

For 120, one of the hots, is uh, the hot, the neutral is your neutral, and the ground is your ground.

Is this magic? Not really, it's the nature of a center-tapped transformer, the center tap being how you get neutral.

For the possibility of you supplying 460 volts, you might consider ignoring any sort of clever wiring techniques and simply run the receptacle wiring "straight-thru" the welder's enclosure and have an extension exiting the back of the machine. Perhaps there is a beefy transformer providing 15 amps of 120 volts from a 460 supply, but the details of doing it safely (ensuring a ground) isn't anything I would find worth the effort; just run an extension cord to the nearest outlet.

I would seriously consider installing a GFCI receptacle; it's not that hard to cut a rectangular hole to fit the GFCI. And it's not just my idea, either:
http://www.lincolnelectric.com/en-us/Equipment/Pages/product.aspx?product=K1690-1(LincolnElectric)
 
Outlet is for water cooler.

Needs to be wired to detect cooler on before you get arc start on the tig unit.

Very important to have working I dont have a clue how it is wired or if wired that way later.
 
SW,

As often happens when I receive excellent advice from knowledgeable people, a lot of what you said flew over my head. ;o(

Heavey Metal just posted what is likely a key point: the outlet is for the water cooler. I'm all but certain he is exactly right. The machine in question is a 1980 Syncrowave 300 "square wave" tig welder. It does indeed have a water cooled tig torch and a water cooler.

So, to be clear, the outlet in question is already there, from the factory no doubt. And to answer your question about how I'm feeding the little monster... it will be hard wired into a sub-panel. The sub-panel will be fed from a 125 amp branch breaker. The sub-panel is a "pass-thru" or "feed-thru" box. It has main lugs at the top and the bottom plus spaces for four 230V breakers.

However, the WELDER will be wired into the lugs at the bottom. This means that the entire 125 amps will feed the welder. The wire between the feeder panel and this sub=panel is 1/0 THHN good for 150 amps. The wire between the sub-panel and the welder is flexible SO 4 conductor cable (AWG#2) ALSO good for 150 amps. The sub-panel itself is good for 150 amps.

Under all normal operating conditions the welder will output 300 amps of AC welding (stick or tig) and draw 120 amps. It will out 300 DC welding amps and draw 70 amps. There is an exception in that in AC mode the machine can be adjusted to an "imbalanced" mode to increase the penetration when welding. At full amperage AND in full "imbalanced" mode (i.e. "maximum penetration") the machine would draw more amperage than I have available to it. In fact it would draw the power of the entire 200 amp service to the shop. In the unlikely event I should ever need such grunt I have ANOTHER sub-panel that can deliver 200 amps (provided I shut down everything else in the shop).

So, the "burning question" I suppose, is really whether under 460 volts the machine was wired with two legs of 460 3 phase and a NEUTRAL or a GROUND. If so, that would at least allow me to understand how they delivered a neutral to this duplex outlet. However, it would still leave me ill at ease as to whether I should hook a WHITE NEUTRAL to the transformer and a GREEN GROUND to the welder frame. I suppose I could (and perhaps should) check for continuity between the transformer frame and the welder frame. I've assumed until now that they were one and the same, and that the separate ground lug on the machine sheet metal was just added insurance in event of an internal fault.

Hope this makes sense.

V
 
Guys,

In case you don't have anything more exciting to read, I have printed and scanned the electrical schematic from the Syncrowave 300 manual that should be the correct version for our specific machine's serial number.

I am hoping this page will show not only the duplex 120V receptacle, but also, from where the neutral and ground are derived. I have two strikes against me. 1) My eyes aren't that good anymore; and, 2) my brain is not very good with schematic diagrams and prints. I tend to think in words and not pictures.

I'm leaning more toward the hypothesis that the machine was originally wired for 460V with two legs of 3 phase 460V and a NEUTRAL connected to the transformer frame and that a separate GROUND runs (or should run) to the machine chassis. That's the only way I can see being able to provide a neutral to the 120V 10 amp duplex outlet. If this hypothesis is true, I assume that the transformer frame is electrically isolated from the welder chassis. Thus, the requirement to keep the neutral and grounds isolated from each other at all points downstream from the service entrance, would be met. I intend to test the hypothesis by using an ohm meter to test for continuity between the point where the machine is now "grounded" (i.e. the transformer frame) and some random point on the welder chassis.

If there IS continuity then I will be back to square one.

If anybody has an epiphany or a eureka moment feel free to post it here.

Thanks again.

V
 

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Outlet is for water cooler.

Needs to be wired to detect cooler on before you get arc start on the tig unit.

Very important to have working I dont have a clue how it is wired or if wired that way later.

Did Miller really build a welder that did this?
I sure have never seen one.
Most radiator/coolers have a separate power switch, so they can be off even when this 110 volt outlet is hot.
I have two Miller tig machines right now, and have used a bunch of other ones- never ran across one that checked if the water was flowing before starting the arc.
If so, it would have to be a feature that could be turned off, anyway, as otherwise, how could you use an air cooled torch?

My employees, over the years, have burnt up the hoses on a few water cooled tig torches, I know its possible to do with most any configuration.

Maybe the fifteen thousand dollar Maxstar 700's do this, but its not listed on the spec sheet.
 
I have a 240 VAC single phase version of the Miller Syncrowave 200. It definitely only has two hot wires and a ground input to the unit. It also has two 120 (115) VAC outlets on the lower face of the machine. These outlets have one hot, one neutral and one ground.

I presume that the neutral is created with the use of the isolation transformer with a connection from one leg to ground for use as a neutral.

I plug my Bernard 2500 water cooler into one of the plugs and it runs whenever the welder is turned on. I don't know whether Miller intended that, but that's the way I do it. I've heard of people starting to weld with the water cooler turned off. There is no switch on my Bernard. I also added a pressure gauge on the output line so that I can instantly tell at a glance whether it's working before I strike an arc. I can't afford a new torch right now.

This is what I believe that Miller does, although I looked at my schematic and I couldn't find it.


iso_trans_2.gif
 
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I have 240 VAC single phase version of the Miller Syncrowave 200. It definitely only has two hot wires and a ground input to the unit. It also has two 120 (115) VAC outlets on the lower face of the machine. These outlets have one hot, one neutral and one ground.

I presume that the neutral is created with the use of the isolation transformer with a connection from one leg to ground for use as a neutral.

I plug my Bernard 2500 water cooler into one of the plugs and it runs whenever the welder is turned on. I don't know whether Miller intended that, but that's the way I do it. I've heard of people starting to weld with the water cooler turned off. There is no switch on my Bernard. I also added a pressure gauge on the output line so that I can instantly tell at a glance whether it's working before I strike an arc. I can't afford a new torch right now.

This is what I believe that Miller does, although I looked at my schematic and I couldn't find it.


iso_trans_2.gif

Woo hoo! An explanation that, although I don't understand it, resonates nonetheless!

I THINK you just said that a transformer can "create" a neutral. As long as the welder's happy, the water cooler's happy (and mine is also a Bernard) then I'm happy! Of course I'll become freakin' ECSTATIC if I can just grok it, too.

V
 
Did Miller really build a welder that did this?
I sure have never seen one.
Most radiator/coolers have a separate power switch, so they can be off even when this 110 volt outlet is hot.
I have two Miller tig machines right now, and have used a bunch of other ones- never ran across one that checked if the water was flowing before starting the arc.
If so, it would have to be a feature that could be turned off, anyway, as otherwise, how could you use an air cooled torch?

My employees, over the years, have burnt up the hoses on a few water cooled tig torches, I know its possible to do with most any configuration.

Maybe the fifteen thousand dollar Maxstar 700's do this, but its not listed on the spec sheet.

My kempi has a water preshure switch.

250 lincoln main contactor when in tig mode is wired throgh cooler

350 is also.

Was repaired by a miller tech(250 lincoln)

Needs to drop out the contacter and leave the cooling fan on.

I have no clue how they came from the factory but one lead and all the service call and parts are free.
 
Mr. Tuck,

The manual Nostalgic Hero linked to provides all of the information you need. You should download this manual and save it, if you have not done so already.

I could not find the 115VAC outlet on the schematic in post number 7 bet the manual does shoe that it is there.

Both the manual and schematic indicate that power is single phase,without neutral, two hots and ground. The manual also shows what size wite is needed for connection based on distance from power source. Read and heed the directions in the manual for safety.

Vlad
 
Mr. Tuck,

The manual Nostalgic Hero linked to provides all of the information you need. You should download this manual and save it, if you have not done so already.

I could not find the 115VAC outlet on the schematic in post number 7 bet the manual does shoe that it is there.

Both the manual and schematic indicate that power is single phase,without neutral, two hots and ground. The manual also shows what size wite is needed for connection based on distance from power source. Read and heed the directions in the manual for safety.

Vlad

Hey Vlad,

According to the Miller site, and based on serial number on my machine the schematic in post 7 comes from the correct manual for my machine, which was built in 1980. The manual that Nostalgic's post pointed to was for machines built in 1987 if I recall correctly.

Thank you for the safety admonition and for your contribution. They are both very important and much appreciated.

V
 
Woo hoo! An explanation that, although I don't understand it, resonates nonetheless!

I THINK you just said that a transformer can "create" a neutral. As long as the welder's happy, the water cooler's happy (and mine is also a Bernard) then I'm happy! Of course I'll become freakin' ECSTATIC if I can just grok it, too.

V

Yes, that's what I learned about isolation transformers right here on this site. For example, I have two Rotary Phase Converters that I built with help from the good folks here. The first one had no neutral fed in. I wanted 120 VAC for the contactors and a red power-on light. I was advised to get a control transformer to isolate the 120 circuit from the 240 VAC and manufacture a neutral. I got a couple of them on the tooling area here and three years later, it's still going.

Just for fun, I built another one. That one had a separate dedicated line with it's own neutral. (4 wires) so no isolatiion transformer was needed. Some folks, when they need 120 inside of a black box, will feed the 120 from one side of the 240 with the ground. This is a no-no since the way that I understand it, there will be power fed into ground. That's never good. Someone else here may have a better explanation.

So, it's clear that Miller and others are powering those low voltage sockets with isolation transformers. If you do a search on this site and also Google Images, you will find more than enough information to solve your problem.

Happy Trails!
 
"I THINK you just said that a transformer can 'create' a neutral."

Sadly, "neutral" is used as a descriptive word for the more correct word "groundED conductor" (emphasis is mine).

The neutral/groundED conductor is usually white, but other colors are OK provided the conductor is "indicated" with white tape.

The groundING conductor (again, emphasis is mine) is usually green, but, again, other colors are OK provided the conductor is "indicated" with green tape.

The schematic diagram (see above) is only partially correct.

The primary side is correct, but the secondary side is incorrect.

The proper way to connect a 120 volt accessory/utility receptacle (NEMA 5-15R or 5-20R) on a machine is to connect one of the transformer secondary conductors to the small pin, the other conductor to the large pin, and to connect the second conductor to the machine's frame, also the receptacle's grounding strap to the same place on the machine's frame.

This, then, correctly implements a "separately derived system" where only one of the two secondary conductors is above ground potential.

Where "severe service" is expected, such as in a machine tool, a Hubbell 5262 (most severe) or Hubbell 5252 (severe) receptacle is recommended. These are made with nylon fronts and have other features which will resist damage when subjected to such service.
 
"I THINK you just said that a transformer can 'create' a neutral."

Sadly, "neutral" is used as a descriptive word for the more correct word "groundED conductor" (emphasis is mine).

The neutral/groundED conductor is usually white, but other colors are OK provided the conductor is "indicated" with white tape.

The groundING conductor (again, emphasis is mine) is usually green, but, again, other colors are OK provided the conductor is "indicated" with green tape.

The schematic diagram (see above) is only partially correct.

The primary side is correct, but the secondary side is incorrect.

The proper way to connect a 120 volt accessory/utility receptacle (NEMA 5-15R or 5-20R) on a machine is to connect one of the transformer secondary conductors to the small pin, the other conductor to the large pin, and to connect the second conductor to the machine's frame, also the receptacle's grounding strap to the same place on the machine's frame.

This, then, correctly implements a "separately derived system" where only one of the two secondary conductors is above ground potential.

Where "severe service" is expected, such as in a machine tool, a Hubbell 5262 (most severe) or Hubbell 5252 (severe) receptacle is recommended. These are made with nylon fronts and have other features which will resist damage when subjected to such service.


Sounds good to me. Whatever you call it, it's a good idea to have a transformer in there somewhere. I figured you would see this and comment.
 
"I THINK you just said that a transformer can 'create' a neutral."

Sadly, "neutral" is used as a descriptive word for the more correct word "groundED conductor" (emphasis is mine).

The neutral/groundED conductor is usually white, but other colors are OK provided the conductor is "indicated" with white tape.

The groundING conductor (again, emphasis is mine) is usually green, but, again, other colors are OK provided the conductor is "indicated" with green tape.

The schematic diagram (see above) is only partially correct.

The primary side is correct, but the secondary side is incorrect.

The proper way to connect a 120 volt accessory/utility receptacle (NEMA 5-15R or 5-20R) on a machine is to connect one of the transformer secondary conductors to the small pin, the other conductor to the large pin, and to connect the second conductor to the machine's frame, also the receptacle's grounding strap to the same place on the machine's frame.

This, then, correctly implements a "separately derived system" where only one of the two secondary conductors is above ground potential.

Where "severe service" is expected, such as in a machine tool, a Hubbell 5262 (most severe) or Hubbell 5252 (severe) receptacle is recommended. These are made with nylon fronts and have other features which will resist damage when subjected to such service.

Hi Peter,

To be clear, this is an outlet that for all the world, appears to have been installed from day one at the factory. I have about decided to take a deep breath, hook up a typical 230V circuit (two hots and a ground), flip the switch, and see what works and what doesn't -- unless I can get some tech help from Miller. About a year ago, when I first tested the thing, I blew a mylar capacitor while cycling and testing the gas on / off circuit with the foot pedal. So I have to order the replacement capacitor anyway. I'm hoping I can get a hundred bucks of tech support along with my purchase ha ha.

It's sort of exciting to get the machine installed. I have two bigger ones (both 500 amp models) waiting in the wings. If the little brudder works alright I may sell the bigger ones. If we ever get where we're actually making money we will probably upgrade to an inverter based machine anyway.

Thanks to everybody!

V
 
"To be clear, this is an outlet that for all the world, appears to have been installed from day one at the factory."

I understood that, for sure.

I have a number of machines which also have so-called convenience receptacles, although those receptacles are not required for any factory-made accessory item known to man. I believe the receptacle was placed there because:

1) a 230/460 to 115 control transformer was required, anyway, to power the magnetic motor starter, and

2) such a receptacle is a convenient place to temporarily power diagnostic equipment, should the drive system require maintenance.

However, I specifically noticed that the manufacturer wired the receptacle properly: narrow pin to the ungroundED terminal of the transformer, wide pin to the groundED terminal of the transformer and "U" pin to the frame of the machine. Also, the groundED terminal was brought to the frame as well, thereby creating the "separately derived system".

Usually, there will be a pair of fuses on the primary (rated for 230 or 460) and a single fuse on the secondary (rated for 115).

In most instances, the conductors to the magnetic motor starter (if so equipped) will not be fused, but the conductors to the convenience outlet will be fused.
 
The Miller Owner's Manual calls out the purpose for the 115 VAC receptacle on the right of the two on the face of the Syncrowave 200. It's used to power a cooler. I have the manuals for the other Syncrowave welders and they are similar.

Sectoin 3-11, Page 16.

Protector CB1
804 267-C
! Turn Off power before connecting
to receptacle or resetting
protector.
1 115 V 15 Amp AC Cooler
Receptacle
Provides 115 volts, 15 amps of AC
power for coolers. Receptacle is
protected from overload by supplementary
protector CB1.
RC2 is a designated use receptacle
intended for supplying
AC power to a Miller-approved
cooler.
2 Supplementary Protector CB1
If CB1 opens, high frequency and
output to the 115 volts AC cooler receptacle
stop. Press button to reset
protector.
 
You learn something every day.
I have never seen a tig machine with a water pressure switch.
I totally believe a Kemppi would have one.
I am surprised a Lincoln does.

As far as I know, though, Synchrowaves do not. Mine sure doesnt.
 








 
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