MM135 tripping 20A breaker??

[hankj]

Hi, gang.

Funny, but this same question was posted on the Hobart board about an HH135. Since I'm BLUE thought I'd post mine here.

Today, for the first (and second) time, my 20A dedicated breaker tripped while I was welding. I probably ran the longest beads I've ever run today, and ran consecutive ones at that - about 4 minutes duration for each of 16 beads. The on-board thermal protection never fired. After it tripped the second time, I plugged my 30A to 20A pigtail tnto the planer outlet and went back to it, but I'm really surprised by this.

In a previous post (Eating Crow) I talked about going to a 12/3 25' cord. Since I did, I've been able to run the machine at it's rated output, and maybe I squezzed a little more too. I can run with V=10 and WS=42.5 with .030 and get a nice, snappy, HOT arc on CO2. Before, on the 12/3 100' cord, my best was V=9, WS=35, and that was the top end. So, can I actually be pulling more than 20 amps? Can that be done?

I'm thinking that the cheapo circuit breaker (a half-height 20A) is just tired, and I'm going to swap it out tomorrow, but I'd appreciate your comments, as always.

Be well.

hank

[fun4now]

10/3 feed

i run my MM135 off a 20A breaker but ran the wire to the plug with 10G only about20ft from my box. the only time i have triped is when i was running through my extention cord also,12G/25ft im going to have to say we are pulling over 20A.my overload was ok also i reset the breaker and was off and running i was outside using flux .030 at the time dont remember but it seem like i was running V=9 ws=7ish i think 75. have not had a prob. scence i went to the shop with no cord and i was running 10/65 all night tonight on some 1/4".
i was thinking of going to a 30A myself but as my trailer is don and im inside my motavation to change what werks is not so much .im hoping to get it done this week.(cant remember when i started saying that LOL)

[Paul Seaman]

hankj:
This is a case where you have met the ragged edge. Don't go crazy but switching the breaker to a compressor rated or slow blow breaker will help during these high power runs. How they work, they still will blow at the rated amperage but they must be held at the breaking amperage for a minamal duration before they will kick out. This slow blow will allow the machine to run at the max longer before kicking out the breaker.

Check it out,

Weld well,

[hankj]

Yeah, I think I'll do that, pjs. All the breakers 1n this panel are "off brand" cheapo's that the guy who built this place must have bought by the carload at a fire sale. Built in '90, so it's all 14 years old. Time for an upgrade!!

fun4now, This outlet is 6' from the breaker! It's #12, but that should do the job if the breaker is OK, I'd think.

I'll let y'all know how it works out.

Be well.

hank

[fun4now]

wonder what miller thinks we should have

i used a 20 cuz i had it and thought id give it a try.
ill have to ask the factory.ill let you know what they say .

[fun4now]

miller said

miller said use a 20A and if you use a extention cord it should be atleast 10gage .so i gess the problem is too small a cord as i know mine is new.here is there reply.
hope this helps.



Hello James,
The 20 amp breaker you are using is correct for your Millermatic 135.
I would assume if you are only having trouble when using the extension
cord you have a problem with the cord itself. It may be severely
undersized or it may have an internal short. I suggest that you try a
different cord that is at least 10ga wire as smaller conductors can
cause problems with machine performance.

If I can be of any further assistance please feel free to contact me.



Best Regards,
Kevin Schuh
Service Coordinator
Miller Electric Mfg. Co.
Light Industrial Products Group
[email protected]
Ph. (920)735-4505
Fax (920)831-4883

>>> "Miller Contact Us" <[email protected]> 06/30/04 01:31AM >>>
Name: james hotchkiss
E-mail: [email protected]
Phone: 585-658-9282
State: NY
Postal Code: 14510
Country: us
i have a miller matic 135 on a 20 amp breaker when i run a 25ft
extention
cord i blow the breaker is this right should i be on a higher braker
what
size do you recommend for the mm135.thanks

[hankj]

Thanks, James.

I've got that bad-boy #8 cord, but I think I'm gonna rearrange some stuff and move the welder close enough to plug it directly into the outlet and give it a run to see what happens.

Be well.

hank

[fun4now]

8 should do

8 should do it bit will be hever than the welder LOL
i havent had any truble when just in the outlet i setup for it.

[Sberry]

If you have an 8 cord moving closer wont make any difference. These machines take a 12 cord, anything more is a waste unless it is at distance. Using a 10 wire is adding to the breaker tripping problem. Remember, bigger cord, delivers more current, going to trip the breaker sooner. Most modern breakers are already slo-blow built in. The only thing you are going to be able to do when running hi currents is to use a dedicated circuit and a 30A breaker. The circuit must be dedicated to over breaker and put it on a 15A style outlet. At short distances you can still use the 12 wire even, up to 50 ft or so. Heavy cords like 10 are needed at long distance

[rick-l]

My added useless trivia.
12 ga. wire has a resistance of 1.588 ohms per 1000 ft. A 100 ft extension cord (200 ft round trip for Mr. Electron) has a resistance of 1.588/1000*200 = 0.3176 ohms. At 20 Amps this would result in a voltage drop of 6.4 volts (20 * 0.3176).
I would think the properties of the arc would be the same but I can't figure out what the welder would do to compensate.

[ASKANDY]

Most welders will weld poorly unless they have a voltage compensating circuit. The small welders like the MM175 or MM135 do not have this. Any voltage change at the arc while MIG welding is a substantial change. Even only .3 - .5 volts will adversely affect the arc. With the welder being roughly a 10:1 step down that means, according to your calculations, 2 volts at the arc would be lost.

Bigger is better on the cord.

A-

[Paul Seaman]

Andy:
Electricity was not my strong suite, but you guys are way past me on all but the last line, BIGGER IS BETTER ON THE CORD!!

BTW, do you think my 4ga-100 foot cord is overkill for the mm210 LOL,

Keep smiling,

[hankj]

pjs: Love ya, man!!

cope: I don't think that's completely true. Like rick-l said, voltage drop is the issue. For a given power requirment, current flow will increase as voltage decreases. If the welder draws 4.6KW at full output at 230 volts and 20 amps, a drop of six volts will mean that you will need 20.5 amps current flow to produce that same 4.6KW. That sustained .5 amp overdraw is (I hope) why the breaker tripped after x number of minutes.

Anyway, I won't get to play until tomorrow. Got the same sort of welding project again, and I'll plug the machine directly into the wall plug and report to the brethren what it is!!

Be well, guys.

hank

[cope]

Originally posted by hankj
cope: I don't think that's completely true. Like rick-l said, voltage drop is the issue. For a given power requirment, current flow will increase as voltage decreases. If the welder draws 4.6KW at full output at 230 volts and 20 amps, a drop of six volts will mean that you will need 20.5 amps current flow to produce that same 4.6KW. That sustained .5 amp overdraw is (I hope) why the breaker tripped after x number of minutes.


hank [/B]

HAnk,

cope never commented on this one. However, I ran the HH140 I field tested on 100' of 12/2 extension cord and had no problems, but I agree with Andy; could well be the cord is defective.

[hankj]

Cope,

Sorry, bud. It was Cary I should have addressed my comment to!! Ah, well. Probably this Cabernet I'm sippin' on...

Be well.

hank