Boost 110v AC to 120v AC or slightly more

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Harold in CR
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Boost 110v AC to 120v AC or slightly more

Post by Harold in CR » Dec 06, 2017 12:51 pm

The power company down here keeps the voltage on the house side to around 108-112v. I keep after them to boost it up to 120v or so, where it should be. As long as I am the only one complaining, they just ignore me. As anyone with AC voltage knows, 108-112 is extremely low.

In my shop when I try to use my 120v Miller Mig welder, there is not enough voltage to activate the relay that starts the wire feed and amperage to start welding. Recently I did manage to get them to adjust the voltage to 118v. That is as high as they would go. I went to the shop and immediately I had the welder starting first click and laying a nice bead. Now, it looks like chikken shit globs and I may click the trigger as many as 30 times to finally get it to catch.

Is there any way for an electronics dumbass like me to come up with a boost circuit for the welder 120v feed ? I believe 30Amps would be sufficient as long as the voltage is between 120-125v.
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Re: Boost 110v AC to 120v AC or slightly more

Post by markz » Dec 06, 2017 4:46 pm

It may be as simple as using a transformer out of a high wattage microwave.
You'd only really need to add or remove one turn from the winding for that 10V gain on the secondary.

Another route is just tapping into the windings.

Variac - http://www.variac.com/staco_Variable_Tr ... er_Map.htm - Expensive for new, but maybe there are used ones for sale somewhere else. Would need a 35A variac.

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Re: Boost 110v AC to 120v AC or slightly more

Post by Hwy89 » Dec 06, 2017 5:48 pm

Google variac variable transformer for a safe simple out of the box solution

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Re: Boost 110v AC to 120v AC or slightly more

Post by markz » Dec 06, 2017 6:40 pm

Another term for Variac is the Autotransformer, on ebay I dont see many rated for 30A or more, so maybe there would be an issue making your own with a microwave transformer because the wires are thin. On my DIY tab welder I used welding grade cable, to get low output voltage and high current.

Another option is to use a generator when using the welder.

EDIT -

A transformer with 5 turns of 8 guage wire on the 110Vac input side of the transformer, and 4 turns output side would net you 132V (110V/5=22V+110V)

10awg can handle 30A, 8awg is 40A. That is totally doable with your average junked microwave transformer. I may have gotten my math wrong, but I'd say you can easily insert 8awg wire and loop it ~5 times, into both sides of the transformer. Just make sure that the directions of your loops stay the same.

You can view how to do it when you search youtube for MOT (Microwave Oven Transformer) tab welding. With mine I grounded the the unit, ground on the outlet to the lug on the transformer itself.

https://www.youtube.com/watch?v=0md3HyohxCk
Last edited by markz on Dec 06, 2017 11:51 pm, edited 1 time in total.

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Re: Boost 110v AC to 120v AC or slightly more

Post by Inwo » Dec 06, 2017 7:05 pm

Use a "boost" transformer, where ever you need higher voltage.
A buck/boost is a transformer with a secondary voltage equal to the amount of boost you need and current required.
So a 10v 10a transformer will boost voltage 10v and supply a 10a load.
A little more to it than that, but it requires a much smaller transformer that you might think.

There are also ferro-resonant transformers on the market that output constant voltage over a small range of input voltages. Very inefficient, but simple.

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Re: Boost 110v AC to 120v AC or slightly more

Post by Inwo » Dec 06, 2017 7:08 pm

Over kill, I think. Haven't done the math.
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Re: Boost 110v AC to 120v AC or slightly more

Post by Inwo » Dec 06, 2017 7:15 pm

Why do the math?
On line calc.
This is with 115 in:
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Re: Boost 110v AC to 120v AC or slightly more

Post by Drunkskunk » Dec 06, 2017 7:47 pm

While fixing your house voltage is worth the time, Its possible that's not the welder's issue.

It sounds like you have a control board issue on that Miller. They are prone to failure, and there are a bunch of trouble shooting videos on Youtube about it. Also, the switch on the gun can start to fail with carbon buildup, so it becomes a higher resistance path. And that causes the motor to fail to feed except at higher voltages. I had that happen, and the switch would cut off under load. For a long time I thought the welder had a failing over-amp protection circuit that was tripping too soon under load. I spend a long time troubleshooting it until I saw the trigger switch was a higher resistance than I'd expect.

My old house has 110v / 220v for most of the time I lived there, and my welder worked fine on 110 plus a 100 foot extension cord. It also works fine on a generator that sometimes dropped the voltage to >90 volts under full load. That's part of the point of the 120 volt series of Miller/Hobart welders. they can run on about anything... Until the switch and/or control board start to flake out.

I was in the process of fixing my welder when I suddenly had to move at the start of the summer, I'm hoping to get it unpacked and repaired in the next few weeks.
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Re: Boost 110v AC to 120v AC or slightly more

Post by dustNbone » Dec 06, 2017 7:59 pm

Agreed. 110 is kind of low but it should still be able to work.

The thing is if you share a transformer with neighbors that are less distant from it than you are, they might be getting 120+ and boosting the output so that you get 120 would mean they're overvoltage due to less drop over their shorter line.

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Re: Boost 110v AC to 120v AC or slightly more

Post by Punx0r » Dec 07, 2017 4:57 am

Agreed, it sounds like a problem with the control side of the welder.

Using a rewound MOT to power the welder is just not going to work. There's a giveaway as to the size of transformer required to run the welder - it's the one inside the welder! That big lump that's many times the size/weight/cost of an MOT...

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Re: Boost 110v AC to 120v AC or slightly more

Post by marty » Dec 07, 2017 7:36 am

I am not a welding expert but a 110V welder seems a little dinky to me. Do you have 220V?. Get a real welder. See lots for sale. Also make sure grounds are all good. Wire between circuit breaker and welder should be proper gauge.
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Re: Boost 110v AC to 120v AC or slightly more

Post by skeetab5780 » Dec 07, 2017 8:55 am

Inwo is right, the proper way to do this is with a buck-boost transformer

buck xformer will bring the voltage down typically either 12 16 or 24v

and a boost xformer will bring the voltage up the same

you could probably get away with a 2.5kva

federal pacific part# K1XGF12-0.25 this will bring 109v to 120v at 20amps

And just because the welder is 120v doesn't mean it sucks. Miller makes portable 120v welders in the $5k dollar range that are pretty amazing.

Harold in CR
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Re: Boost 110v AC to 120v AC or slightly more

Post by Harold in CR » Dec 07, 2017 9:11 am

Too poor the buy another welder. This is wired with 10 Ga directly from 120-240v line from the house 3/2 twist service cable. It's flux wire because it's 56 miles 1 way to get a bottle of shield gas and no vehicle.That's why I'm building the reverse trike. Always worked well and used to do a good job on Aluminum with the argon gas. I don't use it enough to afford the Argon or CO2 bottle. It welds 1/4" steel really weld of beveled and over lapped beads.

A new board is over $600.00. Already priced one through Miller. Don't know electronics to troubleshoot. Do know with proper voltage it welds as good as it ever did. I wrote 30A but, it says 20A on the label.

Took the handle apart and cleaned the trigger switch. Broke open the relay and cleaned the points. Checked and cleaned all grounds, including the feed cable housing ground. If it would work correctly I would get another liner for the wire feed. Nothing else I can do.

I could follow troubleshooting info if someone were to offer. Have VOM+ stuff I know nothing about on it. I HATE being electronics stupid.

Thanks for all input.

Harold
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Re: Boost 110v AC to 120v AC or slightly more

Post by heathyoung » Dec 12, 2017 12:36 am

Old iron core halogen transformers work well for this.

You set them up as an autotransformer. A 50W unit will give you ~4.5A, as you are only using the secondary to do the heavy lifting. Add more in parallel to up your requirements.
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