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I have a problem.  

I am forging down 1" square stock with the #88 striker air hammer, 5HP, 1ph converted to 3ph through a VFD and the 100A breaker at the main service panel trips after about 20 minutes of work.  Shop subpanel does not trip.  I opened up the splice box between the service panel and the shop subpanel and found a mouse family and damaged ground and neutral.  Fixed that and went back to work.  Happened again.  

I have two other splice points between the shop and the main service panel.  One where the wire dives underground and one halfway to the shop underground.  2/0 Aluminum, rated for direct burial, some in plastic conduit, some not.

 I live in way northern New York state.  Things are just freezing up.

Any ideas?  Any tricks for diagnosing/measuring to suggest?

Thanks in advance.....

 

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Amp meter will tell you how much power you are pulling.  A 5Hp motor should be around 39.1 amps at 120 volts plus the VFD circuity adds a little more because transference isnt 100% efficient .  Kinda weird that its only after 20 minutes,  that makes me assume that something is heating up the circuit; increasing resistance and further heating the wire increasing resistance again, etc, that causes the overload.  Also you didnt say what amperage for your sub panel, or what other loads are on it, assuming your VFD is set up correctly I would look into more mouse connection problems with all those splices, If it is wired correctly the mice should not be able to get near the wiring

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1 hour ago, Steve Sells said:

the mice should not be able to get near the wiring

Steve

If ya ever come to visit my shop in the great metropolis of Peavine America make sure to take your heart medicine before you look at the wiring in this old building! :lol:

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10 minutes ago, Irondragon ForgeClay Works said:

and bare wire.

More like barbed wire! :blink:

Okay not that bad… some of it is that high end vintage cloth covered stuff from before they banned it,

the mouses have figured out it makes for great nesting material but not to touch two of the bare wires at the same time! ;)

I got a story about a cat in the loft an some of the wonderful wiring up there I’ll have to tell you an debi next time I see y’all at a hammer in! :lol:

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The sub panel is 100A.  Other loads would be coal forge blower, a half dozen florescent shop lights, a box fan on low aimed at the wood stove.  

I checked the only other accessible splice before the subpanel and it appeared to be fine.  It was a while ago I put it in so I dont remember if I used antiox on the aluminum but it is something I generally do, working it in a little with a wire brush.

 I suppose I will check ahead of the sub panel now.  I did all this wiring myself including trenching the 200 rocky feet to the shop.  A rookie mistake is a possibility.

Any recommendations on an Amp meter?  Is this the same as a multimeter?  I believe I know where to borrow one of those...

Also, should trying a new breaker be considered?

Thanks again 

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+1 for the amp clamp style meter.  Make sure you clamp around each hot leg individually.

Have you confirmed that your hammer is getting adequate oil circulation?  I know that in my shop in upstate NY I have to use a magnetic oil pan heater to preheat my oil till the hammer gets going for a while.

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I suppose running dry and cold could be a possible problem.  I have run it just as it is for years without issue, though.  I usually prime it and let it warm up at an idle while the coal forge is waking up.  

What oil do you run through yours?  I have been using chainsaw bar oil that gets reused on the aux oiler on my alaska mill.  Been doing that for a decade at least.

I have inspected all splice points but the buried one and tightened things up. I am going to run things today in hopes it is just that simple.  If it pops again I will pick up an amp clamp.

 

 

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You're NOT using BAR or USED oil in the oiler are you?!:o Doesn't the manual call for non-detergent 30 weight? Modern detergent oils don't leave the residues to plug the works up like the old stuff does. Even multi weight oils are fine, viscosity and film strength are two different but related things the oil companies started calling it multi viscosity oil so they didn't have to explain all the time. 

If you actually put used or bar oil in the oiler it's a wonder if it's getting any lube, warm or cold. 

Frosty The Lucky. 

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I'll have to check once I get home.  I was advised by the US Anyang rep to use a hydraulic fluid, I think, but would have to check to be sure.  My little hammer has a visual drip indicator so I can see that the oil is flowing at an acceptable rate.

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Striker doesn't have a separate oiler and relies on the fluid drive oil? I was thinking it was a power hammer with a separate lubrication oiler system, I must be thinking of something maybe really old or small company. I wonder what is safe to flush it out with? 

I HOPE I misunderstood or it was mis-written!

Frosty The Lucky.

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I do not use previously used oil in the hammer.  I do use cheap oil and plenty of it.  I use good quality grease for the bearings.  I recycle the oil after it has been used in the hammer in my alaska mill auxiliary oiler.  The bar is 5 feet long and is sometimes cutting through 4+ feet of eastern hardwood which can be difficult for the chainsaw's integral oiler to keep well lubricated.  I am certainly not endorsing doing anything the way I do it.

So, this nuisance tripping I have been tracking... Steve is right, had the splice box been sealed properly those mice would not have caused a problem but I overlooked one spot.  That is done now but the nuisance tripping at about the 15-20 minute mark persisted.

 I will have a chance to run the hammer full out again tomorrow.  If it happens again I will find an "amp clamp"  to meter amp draw.  Should I also consider replacing the 100A breaker at the service panel?

Thanks to all for weighing in

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Ok, so the whole shop is on the 100 amp breaker? Power hammer, forge, six fluorescent fixtures and fan? 50+6+6lights at around what, 4amps?, +another 5 amps or so? Sounds like 80 - 90 amps draw. Not surprising that it might trip a 100 amp service. I used to run a whole shop off extension cords. Getting those loads all going through the same source adds up quick. Those lights, despite being low draw, can add up quick since you are using them all at once. Consider upgrading to a 200 amp and splitting some of that up, or at least for the moment to cut back on use and see if the problem persists.

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Problem solved.  The nuisance tripping has stopped.  Repairing the rodent damage and cleaning/tightening all connections seems to have done the trick.  I have been running the hammer for hours the past few days,  mig welding, plasma, big compressor, etc.  

Thanks to all for the input.

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