A 6/1 Versus the Hobart

[Andre Blanchard]

Just what can a 6Hp Lister type engine do that a 6Hp Honda can't?

A few years ago I bought a Hobart 200 amp DC welder at an auction for $20.  It has a massive 15Hp 3 phase motor, a large cooling fan, the DC welding generator, and a smaller exciter generator all on one long shaft.  I had intended on finding a way of belting it to an engine and to using it, but the only possible place for a pulley is in the center where the fan is which would be a major project.  Second possible use would be as a single to three phase converter for which it would work well, could even connect 24 volts of batteries to the welder section to spin it up to get it started and then use it to charge the batteries.

http://i73.photobucket.com/albums/i208/andre_b/Auxiliary%20Equipment/HobartWelder.jpg
http://i73.photobucket.com/albums/i208/andre_b/Auxiliary%20Equipment/HobartWeldertag.jpg

The tag says 15Hp but it also says 220 volts and 36 amps which is a bit over 10Hp they can not both be right.

But now that I have a 3 phase generator for the listeroids the converter is not needed.  So after doing some spring cleaning I found it possible to walk up to the Hobart and I figured why not see what happens.

With the grease in the Hobarts bearings nice and stiff at 32°F I push the button, DOL to the 25Kw gen head being turned by the 6/1 thru a single 4L1000 belt.  Engine speed drops right now, belt begs for mercy, black puffs of smoke with every power stroke and they are coming slow enough I can count them, contactor in the Hobart is chattering with the low voltage but it is turning and after about 1 1/2 minutes the governor on the 6/1 backs off and things settle down.  With everything spinning again the 6/1 does not seem to be working much harder then before.

The welder seems to be working, makes arcs an sparks, will have to do some more testing.   
If the current controls work it looks like I have a very nice 100% duty cycle DC power supply for my Lincoln Weld Pac 100 flux core wire, which on its own transformer is only good for about 10% at some small max power.  May be worth getting the mig conversion now.

Going to have to do something about that contactor, maybe connect a rod to it thru a hole in the side so I can hold it in by hand until it gets up to speed.

When the 25Kw generator is setup to be turned by the 12/2 and/or the 6/1 the Hobart should be able to burn some good size electrodes.

Thinking I may have to replace the 4L belt with something better for that.

[Andre Blanchard]

I push the button, DOL to the 25Kw gen head being turned by the 6/1 thru a single 4L1000 belt.

Could you explain a bit more how you connect the two devices so that a button push enables the connection ?

The ON button on the welder energizes the 3 pole contactor (big relay) which connects the motor to the power.
The OFF button, or an overload tripping causes the contactor to open.
http://en.wikipedia.org/wiki/Contactor

DOL ?

Jens

DOL = Direct On Line = No reduced voltage starter or other intentional soft start stuff.
http://en.wikipedia.org/wiki/Direct_on_line_starter

But since the generator slows down and the voltage drops so much one could argue that it is doing a soft start anyway.

[biobill]

Syncronicity or what.  Just last night I got an email from a friend wondering if a 6/1 would start his commercial table saw, 18A@220. I think we'll have to give it a try.

 Andre, a video would be really entertaining.        Bill

[tymbo]

Since the table saw is started with no load, I would think it should work.

[adhall]

Andre:

Here is an old trick to help with the contactor chattering:
Put a diode in series with the coil and then put another diode in reverse polarity in parallel with the coil (i.e. as a flyback diode). For example, you could run your hot wire to the cathode of the first diode and connect the anode of that diode to the contactor coil together with the anode of the second diode. Then you connect the cathode of the second diode to the other side of the contactor coil.

What will happen is that the drop-out voltage on the contactor is very much reduced. A side effect is that this will also "cure" an old AC contactor that has begun to buzz. On the down side, the coil will run a somewhat warmer--so watch out for that.

I learned this trick from an old engineer who would use it whenever he had problems with voltage drop in the power that was feeding his relay panels. I have seen this make 120 VAC relays hold in reliably down to 20 VAC or so.

Best regards,
Andy Hall

[Andre Blanchard]

Andre, a video would be really entertaining.        Bill

Here finally got some time when it was not raining.
http://s73.photobucket.com/albums/i208/andre_b/Auxiliary%20Equipment/?action=view&current=Starting_Hobart.flv

Sounds like it's not coming all the way back to full speed, may have to look at the governor.

[Andre Blanchard]

Andre:

Here is an old trick to help with the contactor chattering:
Put a diode in series with the coil and then put another diode in

>>>>

Best regards,
Andy Hall

I looked at the contactor again and if I am not mistaken it has separate coils for the Push button start switch and the hold circuit.  If that is true I could just make the push button circuit DC like you describe and just hold the button in until it gets up to speed.  Then it should not have any heating problem.

[bitsnpieces1]

  If the contactor indeed has two seperate coils. it's possible that you have a contactor that has two sets of contacts for the motor, one for a starting winding and one for a run winding.  This sort of setup would have a start winding that draws a lot more amps than the run winding. 
  It's also possible that the start coil pulls power from the line feeding the motor and the run coil pulls power from the generator side.  The advantage of the generator side pull would be that if anything happened to the generator output the entire unit would shut down as the run coil drops out. 

[ronmar]

More belts:) 

That lower dutycycle on the weldpack is not just for the DC power supply.  I think you will find that if you try and run that little weldpack mig gun at 100%, you will start cooking parts.  At the very least you need to add the gas kit which will provide some cooling to the handle/tip.

Ron

[biobill]

Andre,
  Enjoyed the video, thanks. We're optomistic about the tablesaw and will try it when the snow goes away.  4/18   Where does the IP rack end up once it's started?
                                                             Bill