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  • Sberry
    replied
    Guy I worked for had done it about 2 dozen times, a conversion and made all but a couple hinge parts from 10 or 11 fa, could hav been some 12 but he had couple 3 of us help him put it together , all rather stitched, fast and down on the verts. I remember a company owner stopped by and watched a while one day and he walked over and handed me an extra 20$ Had a gallon of black paint ready to spray on, could paint the while side in a couple quarts easy with 1/2 gallon mineral spirits.
    I have heard of buzzers burning up but I never did one or have never hit a thermal on a machine and tried a few times. When a sprout weld up a trailer, dump box, several times weld quite a bit a whole big ole handful of lo hy pr 7014 or even 6013 with ACs and figured I would just cook one but never did.
    Last edited by Sberry; 11-04-2021, 05:47 PM.

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  • Sberry
    replied
    The page I might have posted was from a red machine about 93, maybe. Was about 1800 bucks maybe, 1850, was the economy simple base model. Its been so long since I cracked the manual but its interesting to note they list the nature of the thermal. If it runs long enough it will shut down on simple switch, if it short circuits it will shut down other means.
    What happens to a AC buzzer if it shorts a secondary with the minimum circuit wire? The breaker must catch the rise before it overheats the wire???? I know a guy can build a semi tanker in the back yard with one, box of 1/8 7014 connected with a 10 cable to the power pole. Ha. 145A, 11 ga on a few roofing truck dump boxes too.

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  • Sberry
    replied
    in a welder circuit the breaker rally doesnt protect the wire or its own cord, the internal of the machine do,,, or the limit, the load calc what ever we might call it for lack of any better wording. Machine will shut down before it hurts the wire its connected to provided its adequate

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  • Sberry
    replied
    I agree, it does limit. Especially the 120V, the machine will output more than a 20 will allow..

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  • WillieB
    replied
    I bet you can't get a dual voltage machine rated at 30 amps 240 volts hot powered by 20 amps 120 volts. Only 1/3 the input heat. The breaker's purpose shouldn't be to prevent internal heat in the welder, but it does limit. Other factors apply.

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  • Sberry
    replied
    This was kind of the point from the beginning when I read a blanket statement like,,, the breakers job is only to protect the wire in the wall from overheating when it actually doesnt on this type of circuit. The wire is simply sized sufficient not to be overloaded and the breaker provides short circuit but must be large enough to let enough current to pass. They size wire by duty cycle more than breaker size. Slightly different than a general circuit can be overloaded from multiple receptacles.
    I see a bit of the reasoning the IBC doesnt allow multiple 240 outlets on one circuit above 20. Done correct not a problem, wrong and we have an overheated wire from multiple loads. .

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  • Sberry
    replied
    Click image for larger version  Name:	20211104_075610.jpg Views:	0 Size:	3.38 MB ID:	618186ok, a pic. I should have been more square but I happened to be looking for some drive roll stuff and this caught my attn. This is an older machine. Looks like they have at least 5 means of thermal before the breaker would even come in to play. One set of thermostats for general but also a set of overcurrents in case the thermals do not react fast enough.
    Last edited by Sberry; 11-04-2021, 07:14 AM.

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  • ryanjones2150
    replied
    You ain’t kidding about them being expensive. When I installed my Bridgeport, the one that was on it was in rough shape. I had to get three different used ones to get all the right parts. The first used one had the wrong coil but the right fusible links. The second had the right coil and the third had an intact reset button. I traded some aluminum welding for two of them and Don helped me work out the right configuration.

    When it came time for my big, old pedestal grinder install and the motor starter was beat up, I just went with the VFD instead. So if any of you guys are looking for some square D motor starter parts, I may have what you’re looking for.

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  • Metjunkie
    replied
    Willie, you just brought back a lot of memories. When I was still amongst the working, I spent many years as a factory maintenance mechanic in a facility built in the forties. They had many pieces of equipment serviced by those old "heater" equipped starters. Even though it's old tech by todays standards, I always marveled at the ingenuity of the folks that came up with that stuff. We had numerous bins of heaters of different ratings. Good times!

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  • WillieB
    replied
    Originally posted by ryanjones2150 View Post
    Sounds similar to the overload protection in a motor starter. I have two or three of those laying around I took off machines when I installed variable frequency drives. Same idea you’re talking about, Willie, for an external overload? They have both the magnetic coil and thermal fusible links.
    Yes, The "melting alloy relays" are not actually relays. They are rotating shaft with a cog wheel. Wrapped around the solder pot is an electric heater. Too much current, heater heats up, melts the solder, allowing a dog under spring pressure to rotate the cog wheel. This is a trigger switch turning off power to the electromagnet.

    Kind of a nuisance, each motor needs a different size units, they are expensive, and few suppliers have them to sell these days. I favor the Current transformer units, nothing extra to buy.

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  • WillieB
    replied
    Originally posted by Sberry View Post
    I was wondering if there was some implication that additional equipment needed to be installed. The switch is operator held so the real danger is minimal but the language left me wondering and seems I have heard the question on other forum. Mohawk is a big outfit, seems I read the manual also and dont recall it. They send a plug and recept with each unit, only thing is they use the same 3 ph twist lock for all.
    Industrial motors seldom have internal thermal overload protection. Sometimes it's built into a magnetic motor control. Older motor controls had "melting Alloy Relays. Newer, usually adjustable magnetic sensing relay. They interrupt the electromagnet coil in the controller.

    If you have anyone looking over your shoulder, Electrical Inspector, insurance inspector, OSHA, or you just don't want the liability, you need some form of thermal overload protection. I'd go with the magnetic motor control. You can mount panic stop buttons anywhere you might need, & it'll stop in the event of a power interruption. Machines that restart without human control are a concern. Another value is these react to imbalance & shut down protecting the motor from disaster.

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  • ryanjones2150
    replied
    Sounds similar to the overload protection in a motor starter. I have two or three of those laying around I took off machines when I installed variable frequency drives. Same idea you’re talking about, Willie, for an external overload? They have both the magnetic coil and thermal fusible links.

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  • Sberry
    replied
    I was wondering if there was some implication that additional equipment needed to be installed. The switch is operator held so the real danger is minimal but the language left me wondering and seems I have heard the question on other forum. Mohawk is a big outfit, seems I read the manual also and dont recall it. They send a plug and recept with each unit, only thing is they use the same 3 ph twist lock for all.

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  • WillieB
    replied
    NEC offers exemptions for fractional horsepower motors. Otherwise, NEC requires thermal overload protection. Many choose the "I don't need to be inspected" loophole.

    If a motor doesn't have internal overload protection, it needs external thermal overload protection.

    In the old days we used "heaters", thermal overload devices. They were a solder pot surrounding a shaft. A heater surrounded the solder pot. As amperage increased, the incandescent heater got hotter. Melting solder allowed the shaft to rotate. a trigger moved & tripped a switch.

    They are expensive. Some go Amazon, find cheap ones.

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  • Sberry
    replied
    I have to get a better picture of the label . I got a question about the nature of the protection. Says motor not externally protected. I dont see it internally protected. Says the breaker needs thermal and magnetic,, well duh but a breaker isnt going to provide motor protection at that high rating? I have the single phase model.

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