How To Figure Amps on 110V 400 Watt Motor

any electrician (doest have to be marine) with an amp meter and a VOM should be able to isolate your problem in a couple of minutes of testing

You're probably getting some voltage bleed that is tripping the ground fault...I would just work around it...is it a wet location?

I=V/R will get you there

That's less than 4 amps. Something else is tripping the GFCI.

I highly recommend one of these circuit testers.

Read what Wiki says. I've got two of these. They're great for quicky checking.

A receptacle tester being used to verify the proper wiring of an outlet. For this particular tester, proper wiring is indicated by the two yellow lights.

The much more important role of the outlet tester is to not only verify that electricity is present in the outlet but that the outlet is properly wired, with each plug being connected to the proper wire in the building's wiring. There are two primary reasons for testing

IDEAL INDUSTRIES, INC. - E-Z Check® Circuit Testers

Be sure to get the one with a GFI test button. If it works, the problem is with the motor. Has nothing to do with total amps, but miliamps to ground (not neutral. No, ground and neutral are "not the same") -- JHF

Current should be less than 4 amps (400W divided by 110v), but it's the leakage that's tripping it.

Maybe it's the mains noise supression components (capacitors from live to ground and neutral to ground) that are doing it.

Del

I don't know what you mean by servo motor, but if it has carbon brushes and you used it for a long time, the carbon dust, accumulated on the holders, to the ground can make your motor ground fault trip also. In this case blowing it clean inside with compressed air might solve the case. An other scenario can be caused by the isolation of the coils shellack. This motor should consume about 400/120 =3.3 Amps.

It's current leakage from the hot wire to ground that's causing the trip, not an over current condition. If I had all of the toys from work I would perform a high pot test between the black (hot) lead and chassis to look for a leakage path. Without that tool, I would examine the wiring to see if anywhere the black wire insulation is cracked, pinched or otherwise compromised. I would also use some canned air to clean out the brush dust.

Besides all the other answers, it could be a bad breaker. I had this problem with some old Federal-Pacific GFCI breakers.

It keeps kicking the Ground Fault only. Do you have another GFCI circuit that you could try it on? If it trips another one, your stitcher is faulty. If not, your breaker is probably bad.

If the GFI is tripping, you have a potentially lethal situation. GFI's do not trip because of over current, they trip because of a difference in current between the white and black wires. Follow Redskis advice below.

If you really, really need to work. Wear dry clothes and dry tennis shoes. Preferably long sleeves and pants. Place the machine on dry auto floor mats. You should be standing on dry plywood. Did I mention "dry".

This should keep the GFI from tripping, until you can get it corrected.

The GFI balances the input current to the device against the return current from the device. A leakage path that causes these currents to be unequal will cause the GFI to trip with current differences in microamps. Providing a separate ground to the machine and bypassing the GFI would probably get you by, but I can't recommend it, especially without knowing more about the installation...Clint

There are few simple ways to know if motor is leaking current to ground or has some poor connectivity node in the power paths.

1) Measure voltage at the mains distribution point and then across the plug which feeds the motor controller. The voltage need to be within 0% to 1% (on high side) error at best.

2) Measure current in live wire Li and also in neutral wire Ni separately and see of Li > Ni. If Current difference is significant then somewhere either in the controller or in the motor current is going through Ground path which should normally have near zero current.

3) If you have ground / earth connected to the controller and if its harmonic filters are finding differential power harmonics over live and neutral lines then they will run this current into earth / ground path also if filter is wired to earth line also. However, this part can be investigated by looking into internal diagram of the controller's technical manual.

Good luck.

Your problem is not the amperage! Your motor has a high leakage current that trips the GFI.

If you have an isolation transformer on hand, with a size or capacity of more or less about 500 VA, you can use that temporarily. Plug your servo motor into it then plug the transformer to your GFI outlet. The isolation transformer will solve your high leakage current problem..

Remember the isolation transformer you need to use must have a 1:1 turn ratio meaning, it has the same input and output voltage rating!

Good luck!

Yes, an isolation transformer between the GFI and your servo system should take care of it. A 1KVA would be my choice.

I'd say that we've managed to confuse and befuddle the poor OP with all our collective intellectual one upmanship, again.

The contributions of Shyam and Winfield Hill are especially confusing, especially to a simple fisherman. While I certainly don't suggest that either contribution is wrong, I do suggest that they are way too technical for the our friend who is seeking help.

It seems to me that through it all, what we have here is failure to communicate, again.

I'll save you all the trouble of voting this OT.

In case it didn't filter through the verbiage, the GFI checks that the current that comes in on the hot (small blade) side goes out on the neutral (large blade) side. If there is an imbalance, it shuts the outlet down. The amount of the imbalance (the leakage) could be lost in an inside short and escaping down the grounding pin or externally by any of the several methods described in the posts above. This seems to imply that the leak is in the equipment or the wiring.

As someone said, another possibility is that the fault may be in the GFI.

Thank you all for the lessons in current. Yes, some were very much over my head.However, I sifted through enough of this to solve the problem.

My old stitcher ran off this Ground fault outlet for about 6-7 years. The Motor was belt driven and was about twice as large as this one.

THIS motor is smaller, has no belt and has a rheostat that lets me set the rpms from 390 to 2100.

The machine is larger and judging by the power it has to ram a 80mm steel needle through a 4 ply layer of 1000 denier netting, I'd say it was twice as strong.

To solve the problem:

I simply ran a separate line from my meter box to the machine. Its on a 20 amp circuit with just a 2 amp fan. the machine itself has a fused connector.

I never work on anything wet and the machine is on a plywood floor. It runs top end now.

Thank you all. I may never really know what caused the GF to trip, but I have more of an understanding about what 'could' cause it to happen. Our work is about 70% hand sewn large mesh nets, 20% micro mesh 12mm through 750µ ( sewn only on the stitcher) and 10% rope and cable splicing. With this new stitcher , me and the wife can increase production time on those micro mesh nets, and take in more work in that area. the old machine was just plain worn out and slow.....like me!

Once again, another lesson learned from the CR4 Ol' Skool gang!

Thank you all again.

nice post

Had similar problem with the GFI that was feed an outlet in my garage and three bathrooms. It would always happen after a storm with lightning and heavy rains with a high humidity.

The wire went from the panel box to the GFI located in the garage and then to non GFI outlets in the baths. For one of the baths I ran wiring through the basement to the bath and installed its own GFI. For the one bath on the 2nd for I did the same but through the attic. Couldn't do the for the other 2nd floor bath because the wiring was located on an outside wall, had a mirror adjacent to the outlet and most of all I couldn't get to above it due to the angle of the roof. What I did for that was change from feeding from "through the garage GFI" to feeding it and a GFI that replaced the duplex outlet in the bath in "parallel". Found out before this that the GFI was tripping due to spurious electrical pick up on the long length of wiring after the GFI. Now all the sockets are GFI and I haven't had one trip since the changes were done.

This problem was most inconvenient when the wife would wake me up on a cold early morning saying that her hair dryer didn't work. I would then have to go down to the cold garage to reset the GFI!

Locate your GFI closer to the machine. Preferably use it as the outlet that you plug your machine into.

Good Luck, Old Salt

Like yours, I have a GFI equipt outlet in the garage that also feeds power to 4 other external outlets that are around the outside perimeter of the house.. Even those outlets were not being used, I found from time to time that GFI trips! To stop any unnecessary tripping of that GFI, I separated or isolated the wires coming out of the GFI that feeds power to the outside outlets from the others. I relocated them the away from the rest of the house wiring. In my thoughts by doing so, I will minimized stray capacitance between other house wires, which in turn should lower corresponding leakage currents. So far it seems to work since no more annoying and unnecessary power interruptions!

Yes, "If it works, don't fix it". You've got the problem solved and your solution sounds good.

After I did these wiring changes, and after a sufficient length of time to see that the problem was fixed, I asked two neighbors about the problem and how they would solve it. Neighbor #1, the PhD in EE, had no realistic solution except if I rearranged the electrons as they traveled through the protons in the copper of the wires. Neighbor #2, the electrician, told me what the problem was, how to fix it and kidded me for asking him such a silly question. When I told him that's what I had done he said I owed him not a can of beer, his usual rate for consultations, but a 6-pack for asking dumb questions that I already knew.

Yes, common sense solves most things.

Good Luck, Old Salt