Melting extension cord

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Pipefitters/Welders using 12/3 extension cords for rod caddy, grinder, etc. have managed to melt a cord the entire length, but only the green(ground) conductor.They are using a DC welder. I believe this cord is completing the welding circuit. Is this possible considering DC?
 

480sparky

Senior Member
Location
Iowegia
I got a nickel that says they're home-made cords, or cords with new ends on 'em, and the welders didn't care what color they used so long as the machine worked.

You sure the green is used for grounding?
 

mcclary's electrical

Senior Member
Location
VA
Pipefitters/Welders using 12/3 extension cords for rod caddy, grinder, etc. have managed to melt a cord the entire length, but only the green(ground) conductor.They are using a DC welder. I believe this cord is completing the welding circuit. Is this possible considering DC?




I think you're right. Tell them to keep their grounds right next to where they are welding.

I've seen welders melt the babbit right out of bearings.

I've seen welders ground through communication wiring, ruining everything in the conduit.

I've seen welders ground through EGC and burn them in two.

I've seen welders ruin the computer in a rubber tire loader.

And the funniest one, I saw a welder drawing a ground through about 100' of 3/8" galvanized steel chain that was roping off a certain area of production equipment. The entire length of chain got SO HOT,,,you could not touch it, it would burn your hand. The tiny losses in between each link added up to a huge amount of heat, it was too hot to touch

Tell the lazy welders to drag around two leads everywhere they weld, not just one.
 
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wawireguy

Senior Member
I'd take a look at the welder also. See if it has new plugs put on it. Make sure all the plugs are correct for amperage and voltage. I've seen jury rigged plugs get people hurt on the jobsite before. Such as cutting prongs to make them fit.
 

iwire

Moderator
Staff member
Location
Massachusetts
Seen it a number of times, it is welder current on the EGC and it does not matter at all if it is an AC or DC welder.
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
100711-133 EST

I had a problem at the Chrysler Eldon Ave axle plant.

This was on a pinion shim station. The machine would weigh probably 8000 to 15000 #. It was made from 1/2 welded steel plate plus a number of other heavy steel items. Mounted from this was the shim verifier and shim rack. The shin verifier and rack support were made from 4 or 5 inch square steel tubing with 3/8 wall thickness. This structure was welded to 1/2 inch thick steel plates that were in turn bolted to the main machine frame.

The electronics were in a NEMA-12 box attached to another place on the main machine frame. Belden 8723 connected the electronics to the LVDT in the shim verifier. The LVDT is not insulated from the verifier and the electronics common is connected to the machine frame.

The welders placed their ground wire on some part of the main frame and welded on the shim rack some place. Their gound should have been placed close to the weld point but was not. You might expect that with the amount of solid steel and three bolted interfaces in parallel that the voltage drop from the welding ground to to the weld point might be small. But it was great enough to burn-up the LVDT, its cable, and some electronic components. Inductance rather than resistance may have been the cause of an excessive voltage.

The main point is that welders should connect their common lead very close to the work spot and directly to the material being welded and not thru some interface.

.
 

wptski

Senior Member
Location
Warren, MI
100711-133 EST

I had a problem at the Chrysler Eldon Ave axle plant.

This was on a pinion shim station. The machine would weigh probably 8000 to 15000 #. It was made from 1/2 welded steel plate plus a number of other heavy steel items. Mounted from this was the shim verifier and shim rack. The shin verifier and rack support were made from 4 or 5 inch square steel tubing with 3/8 wall thickness. This structure was welded to 1/2 inch thick steel plates that were in turn bolted to the main machine frame.

The electronics were in a NEMA-12 box attached to another place on the main machine frame. Belden 8723 connected the electronics to the LVDT in the shim verifier. The LVDT is not insulated from the verifier and the electronics common is connected to the machine frame.

The welders placed their ground wire on some part of the main frame and welded on the shim rack some place. Their gound should have been placed close to the weld point but was not. You might expect that with the amount of solid steel and three bolted interfaces in parallel that the voltage drop from the welding ground to to the weld point might be small. But it was great enough to burn-up the LVDT, its cable, and some electronic components. Inductance rather than resistance may have been the cause of an excessive voltage.

The main point is that welders should connect their common lead very close to the work spot and directly to the material being welded and not thru some interface.

.
gar:

I was told that at one time at Ford Sterling, one couldn't weld on a machine without the engineering department's okay. I always tried to get the welder to find a ground as close as possible to the weld point. Not good to have current flow through bearings costing thousands of dollars at times!

Even after I hired in, it wasn't allowed at all on the Gleason gear cutters.
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
100710-1451 EST

bill:

I never had any damaged equipment at either Sterling or Van Dyke from welding. But after about 20 years I did have to wash some boards because of grease and dirt accumulation.

What more have you learned about the Escape electric clutch at the rear differential? I only drive our Escape on occasion and that has not been in bad weather. The Aerostar that I drive mostly has outstanding performance from the electric control of the transfer case clutch. I can full throttle accelerate from a stop across the plastic white stripes on a wet day at an intersection and not even feel any slip. I provided the test equipment for the transfer case test machine at Dana Columbia.

Electric clutches in differentials, the drive shaft, or transfer case are very useful and better than some of the prior solutions. The current Jeep Rubicon uses an electric clutch in both the front and rear differential. Thus, both front and rear differentials can be locked-up when needed, and effectively lock all the wheels in syncrhonization, but when when not locked perform well on dry pavement.

.
 
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wptski

Senior Member
Location
Warren, MI
100710-1451 EST

bill:

I never had any damaged equipment at either Sterling or Van Dyke from welding. But after about 20 years I did have to wash some boards because of grease and dirt accumulation.

What more have you learned about the Escape electric clutch at the rear differential? I only drive our Escape on occasion and that has not been in bad weather. The Aerostar that I drive mostly has outstanding performance from the electric control of the transfer case clutch. I can full throttle accelerate from a stop across the plastic white stripes on a wet day at an intersection and not even feel any slip. I provided the test equipment for the transfer case test machine at Dana Columbia.

Electric clutches in differentials, the drive shaft, or transfer case are very useful and better than some of the prior solutions. The current Jeep Rubicon uses an electric clutch in both the front and rear differential. Thus, both front and rear differentials can be locked-up when needed, and effectively lock all the wheels in syncrhonization, but when when not locked perform well on dry pavement.

.
gar:

I've learned that nobody knows how it works but lots think they do! They call it AWD but really it just automatic 4WD. Dealers know nothing about it at all, call Ford and they say ask your dealer!:confused:

Here's the closest one can come to real AWD: SH-AWD

The 4WDs make a "hoot" sound every time you leave a stop under moderate or less throttle. A TSB comes out to reflash the 4WD module. I had it done, nothing changed. Later another TSB comes out that it's in "all" vehicles with the new 6F35 6-speed transmission made at the Van Dyke plant make the sound coming from the drive chain. The sound isn't that bad but some had the chain replaced only to have the sound return.

Funny thing is that if you pull the fuse that powers the 4WD module, the sound stops!:D I think that they haven't diagnosed the problem yet.
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
100710-1904 EST

bill:

First, I will describe how the Aerostar works. This is a full time all wheel drive with a differential in the transfer case. The gearing is such that under normal conditions about 60 to 70 % of the drive torque goes to the rear end, and the balance to the front end. The rear end has a limited slip differential, and the front a standard differential.

There is a front and rear tooth wheel in the differential. Associated with each is a Hall sensor magnetic pickup. If the difference in the differential count between these two sensors exceeds a few counts in a given time, then the electronic control energizes a clutch that locks-up across the differential. This lasts for about 6 seconds. The assumption is that slip is occurring between front and rear when this difference is larger than the threshold. What this system lacks that would make it better is the electric clutches in the differentials such as used in the Jeep Rubicon.

Following is my guess on what is done in the Escape. This is essentially a front wheel drive car with the addition of a full time solid transfer case to supply some torque to the rear. The clutch at the rear just in front of the differential is similar in size and power capability to that in the Aerostar.

From our previous discussing I believe the maximum current to this clutch is in the range of 10 A. This would mean maximum power would be in the range of 120 to 140 W. This is very similar to the power dissipated in the large electric clutches we use in the pinion preload adjust machines. These clutches are good for upwards of 1000 #-FT before the air gap is modified for quicker dropout.

You have also indicated that under normal driving conditions that substantially less current is supplied to the Escape clutch than the 10 A level. This means less torque, but some torque.

There will always be some difference in front drive shaft RPM vs rear, and this changes with tire pressure, stopping, accelerating, and turning. Most of the time this is a very small amount. At 2000 RPM for the drive shaft the difference might be more than 0.1% and less than 1%. If as high as 1%, then it is 20 RPM. Suppose under slip conditions the torque slip point of the clutch is 200/4 = 50 #-FT. 20 RPM * 50 #-FT / 5252 = 0.2 HP = 142 W. Not a lot of power to be dissipated in the clutch. It will produce clutch wear. However, it is providing all wheel drive that improves stability. When real solid four wheel drive is required the clutch would lock-in with full current.

Can you instrument to monitor the front and rear pulse rates to determine how much difference there is? If it seems large, then you could see if changing either front or rear tire pressure to reduce the difference would reduce the noise.

Does my guess at all seem like it is what they are doing?

.
 

wptski

Senior Member
Location
Warren, MI
100710-1904 EST

bill:

First, I will describe how the Aerostar works. This is a full time all wheel drive with a differential in the transfer case. The gearing is such that under normal conditions about 60 to 70 % of the drive torque goes to the rear end, and the balance to the front end. The rear end has a limited slip differential, and the front a standard differential.

There is a front and rear tooth wheel in the differential. Associated with each is a Hall sensor magnetic pickup. If the difference in the differential count between these two sensors exceeds a few counts in a given time, then the electronic control energizes a clutch that locks-up across the differential. This lasts for about 6 seconds. The assumption is that slip is occurring between front and rear when this difference is larger than the threshold. What this system lacks that would make it better is the electric clutches in the differentials such as used in the Jeep Rubicon.

Following is my guess on what is done in the Escape. This is essentially a front wheel drive car with the addition of a full time solid transfer case to supply some torque to the rear. The clutch at the rear just in front of the differential is similar in size and power capability to that in the Aerostar.

From our previous discussing I believe the maximum current to this clutch is in the range of 10 A. This would mean maximum power would be in the range of 120 to 140 W. This is very similar to the power dissipated in the large electric clutches we use in the pinion preload adjust machines. These clutches are good for upwards of 1000 #-FT before the air gap is modified for quicker dropout.

You have also indicated that under normal driving conditions that substantially less current is supplied to the Escape clutch than the 10 A level. This means less torque, but some torque.

There will always be some difference in front drive shaft RPM vs rear, and this changes with tire pressure, stopping, accelerating, and turning. Most of the time this is a very small amount. At 2000 RPM for the drive shaft the difference might be more than 0.1% and less than 1%. If as high as 1%, then it is 20 RPM. Suppose under slip conditions the torque slip point of the clutch is 200/4 = 50 #-FT. 20 RPM * 50 #-FT / 5252 = 0.2 HP = 142 W. Not a lot of power to be dissipated in the clutch. It will produce clutch wear. However, it is providing all wheel drive that improves stability. When real solid four wheel drive is required the clutch would lock-in with full current.

Can you instrument to monitor the front and rear pulse rates to determine how much difference there is? If it seems large, then you could see if changing either front or rear tire pressure to reduce the difference would reduce the noise.

Does my guess at all seem like it is what they are doing?

.
The Escape has no transfer case to speak of. A PTU turns the rear driveshaft all the time. Not sure when we spoke before if I had my ScanGuage-II to monitor rear wheel torque all the time. I got tired of have my console apart and using a scope all the time.

I have no way to monitor the ABS wheel sensors which you speak of. Yes, the Workshop manual speaks of all wheels being within 2 1/2 MPH of eachother. There are other Ford vehicles that use that percentage split system.

"They" say when front wheel slipage is detected increased torque is sent to the rear wheels. I tried to check this on snow in a cemetery but the results were inconclusive and I also thought later that I "maybe" should have shut off the traction control which is a ABS function which can also take full control of the 4WD too.

It's also written that increased torque is sent to the rear under heavy throttle too. In theory that should be 50% but all the way to the floor only shows around 33%. There's a test in the manual which one needs a IDS(Ford PC and software) where you call up a certain PID and force 100% rear wheel torque. If the vehicle binds or resists turning, it working properly. Another test is a hard turn <5MPH should generate >20% rear wheel torque.

This same system in a Ford Edge is tagged as AWD and the same for the Fusion. At least that SH-AWD that I link to has a clutch pack at each rear wheel. I once had a link to a Fusion AWD moving graphic where you could select different driving conditions and it showed how power was deverted to each wheel. It showed on a winding "S" curved road, torque shifting from side to side on the rear wheels. The system doesn't work that way at all but maybe that's why that page no longer exsists too!:D
 
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