Tandem SAW: Flaring Up for no good reason

Date 02-21-2016 20:59

Troubleshooting is what it is...and I think I've gone through near everything.

Here's the set up:

We run two Lincon Power wave 1000's in tandem (AC on lead, AC on trail, one wire per power supply). And last night after two successful welds the machine has been flaring up.

I've gone through and inspected/replaced all sense leads and work leads. Made sure all contacts are indeed making contact, as well that the sense leads are not close to the work leads.

The Lincoln Power Wave isn't throwing any errors. And on our controller We can see the amps and volts jump wildly.

There was a temporary change from these symptoms when I turned the wave balance on the Lead down from 75% to 50%...this helped for 45 seconds, and then the system started spiking again.

What's really peculiar...I ran JUST the Lead...no problems. And then I ran JUST the Trail...no problem.

But shove them together and they don't seem to want to play nice.

The electrode spacing is proper, the base metal is clean and regular.

The Phase offset for the Trail is 90° off from the Lead.

All the variables in the program are identical to our other systems... Using a Fluke 355 AC/DC clamp meter the volts and amps are the same as what is displayed on the controller.

I'm starting to think it's the power supply...but it's that dang single wire/power supply test I did that bugs me.

Any thoughts out there as to other ideas to try? Thank you all for your help.

Thanks!

By 803056

Date 02-21-2016 21:21

What was the part geometry where the unusual behavior occurred? Could you possibly be encountering arc blow near the end of the joint?

Al

By Bowler_Hat (**)

Date 02-23-2016 12:49

Cylindrical... large 14' diameter pipes with two opposing carbon arc blocks. Great idea though.

By Lawrence (*****)

Date 02-22-2016 01:17

It's Arc-blow.

But Lar, we are using AC power, doesn't that make arc-blow impossible?

Nope...

How are your work leads connected?

Welding toward lead?

Welding away from lead?

Multiple work leads?

Say more about your work leads

By 357max

Date 02-22-2016 15:41

Question, what is the wire feeding like? Is it intermittent? Jerky? Drive roller alignment? Drive roller pressure? Liner plugging, wire spool brake too tight?

By Bowler_Hat (**)

Date 02-23-2016 12:41

When the voltage dropped the wire would stub...rightfully so. After the stub the amperage would shoot up trying to compensate. The drive roller alignment is parallel as well their pressure is dialed in properly (4mm wire...this stuff is thick). As well, the brakes we at that nice balance of free flow without running away. Thanks for the ideas!

By Bowler_Hat (**)

Date 02-23-2016 12:48

We work on 14' cylinders, and the ground is attached via two large carbon blocks (like massive brushes on an electric motor) mounted opposite of the electrode (spaced about ~45° apart). For sure, there are multiple work leads...6 in fact.

We even went so far as to remove the carbon arc blocks and set up the old solid copper Work-load clamp (The kind ya bolt down with a 3' pipe wrench.

All very good items to consider.

Thankfully, we have identical 'lines' here, and so we moved our machine next door, hooked it up to the other line, and the issue persisted. With that, our feeling that the ground connection was the issue resided not in the grounds/sense lead.

The awesome help at Lincoln even helped us check the voltage, amperage, etc. etc. at the studs on the power supplies. That's some phenomenal diagnostic tools.

By Bowler_Hat (**)

Date 02-23-2016 12:39

Got to love general issues right? Ha.

The end result was a bad controller factory software (I.E. Changed the controller, same set up, all issues resolved...go figure). The hardest part of the entire two day ordeal was getting the Controller manufacture/tech support to say, "Huh...guess something wrong in the controller. I have no idea what."

Does anyone else in the industry experience finger pointing when asking controller engineers for help in diagnosis? Understood, they only see the picture that is painted for them over the phone.

Thank you all for your questions /help.

P.S. Lincoln tech support is stellar!

By Lawrence (*****)

Date 02-23-2016 13:15

Controllers! And I was so sure it was arc-blow.

Controllers are at least a little less mysterious.

We should talk more off-line about AC SAW... I'm in the R&D stages of some PQR's for "tiny twin" AC SAW operations.\

Lincoln has really been Aces for us with both SAW and GMAWP, helping develop some proprietary wave forms. Although when Lon Yost retired I cried a little... (I'm sure Lincoln did too)

FYI... I am a big user of Lincoln "CheckPoint" data monitoring and "PowerWave Manager" snapshots. Those snapshots can really help the Lincoln engineers pinpoint problems (like controller vs power supply). Plus, with Checkpoint, I know real time about every minute of arc time, every ounce of filler, and every amp and volt on each weld over 4 states and two countries.

The PowerWave platform including (AC/DC 1000) is super controllable. Meaning once you dial in the WPS's for production you can lock the unit down tight, which goes a long way toward correct weld sizes and knowing that each weld is in parameter range, and who trends toward compliance or non-compliance. (OEE)

By 803056

Date 02-23-2016 14:00

Once you've checked everything that simple, you have go for the more complex. Machines aren't infallible.

Lincoln has a good reputation for customer support. That is often the deciding factor when making a major purchase.

While I'm not familiar with all of Lincoln's machines, I did have problems with a couple of power supplies in the field on a job where we were only fifty yards from the ocean's edge. There was a series of LED that allowed one to run diagnostics and based on the sequence, it would pretty much point you in the right direction. As it turned out, I isolated the component (a bank of relays) from the steel frame to avoid the shunting action/shorting caused by the moist salt air.

It was one of those things that made you go beyond of the everyday problem solving. How often do I have to borrow down through the wiring diagrams? Not very often, but it is nice to be able to do so and make sense of all the little black lines.

Al