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  • Yet another welder wiring question

    I was thinking how welders (or mine at least) don't require a neutral, but rather a safety ground. After thinking how safety ground isn't really supposed to be used as a current path (that's my understanding anyway), I was wondering if anyone can verify that the grounding wire on a welder, under normal circumstances, does not flow current through it.

    Thanks.

    Chad

  • #2
    Disconnect it.

    If it stops working, then it was being used.

    Just remember either way you may now have a dangerous appliance on your hands.

    Also, I don't know anything.

    Lets see what the experts say.

    John.

    [This message has been edited by zl1byz (edited 05-08-2005).]

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    • #3

      The potential across the two power legs is 220/single phase. The potential across either power legs and neutral is 110v/single phase.

      The two power legs comming in (L1 and L2) are 110v 60 hz AC. One leg has the inverted sign wave of the other. Neutral normall sits at 0v so when you're using the potential across L1 and L2, then you don't need neutral anymore.

      You need the ground for safty (mainly for lighting strikes).

      -Adrian


      Comment


      • #4
        I always thought the ground safety was connected to the metal case of an appliance so that the case itself could not be raised above ground potential from a wireing falt.

        John.

        Comment


        • #5
          <font face="Verdana, Arial" size="2">Originally posted by zl1byz:
          I always thought the ground safety was connected to the metal case of an appliance so that the case itself could not be raised above ground potential from a wireing falt.

          John.

          </font>
          Yup.. The ground does exactly that, but it also grounds the applicance so lightning won't kill you if it stikes the L1 or L2 feeds comming into your house..

          -Adrian



          [This message has been edited by 3 Phase Lightbulb (edited 05-08-2005).]

          Comment


          • #6
            I run four wires on my system. Two hot leads, one "common" to the ground post (ground) of the welder supply line and a green ground lead (true ground, hard ground) to the chassis.

            I'm not electrically inclined, so dont take my methods to earth (ground) JRouche
            My old yahoo group. Bridgeport Mill Group

            https://groups.yahoo.com/neo/groups/...port_mill/info

            Comment


            • #7
              In reading this thread I am puzzled by an explaination for 110/220vac at the service entrance. Namely, "inverted sine waves" on the 120vac from neutral to L1 and L2 respectivly. Since L1 and L2 are the ends of of the secondary of the power transformer and "neutral" is a center tap, how is it possible to have a positive potential on one half of a winding and a negative potential in the other half? As I see it, the potential, during one half cycle, could be L1 plus and L2 negative. L1 pos. to neutral and neutral pos. to L2. Very similar to a voltage divider. Please enlighten me as to where I am wrong. Thanks
              Jim

              Comment


              • #8
                Mostly, a ground is a better conduction path to take machine offline before it sits there "hot" looking for another path (ie: you) that is why the ground must be sized according to the infeed conductors.

                It is a saftey wire.

                3ph: Lightning has so much energy a small ground wire evaporates. Usually when a home or business loses it's ground it is because lighting hit close in the area. It blows it off at the groundrod, or in the panel, or where it makes contact with a piece of equipment. If it hits a electrical service, the insulation has holes blowed in it effectively grounding it. A MOV across the circuit is effectively a back to back zener diode that sacrifices and shunts the current to the other leg during a spike shutting down the circuit. (lil red/black wafer that looks like a capacitor)

                Nikola Tesla had a way of using "that" energy developed by the earth. His Wireless power transmitter ran on the static naturally developed by the earth. He induced a harmonic vibration to attune the pickoff ground rod and a aerial for the other side.
                Using the two devices I was able to percieve .0001 volt dc. Using a Tuning fork with points he was able to generate enough power to run a light bulb without wires. This was in Colorado where the air is really dry and the capacitance of the earth is greater.
                Some of his other experiments destroyed the power generation plant close by breaking down the insulation properties of the generator. Horses used close by had sparks going from thier hooves to the cobblestones.
                Imagine if he had the use of transistors and other switching circuits we have today.
                I studied the patent applications on his no-wire transmitter for weeks before I finally decided there was no real mystery, it was a tuning fork I was looking at across the coils. You'd start the tuning fork by striking it with a wooden mallet, the bar of the tuning fork would come into Harmony with the transformer hum and maintain the frequency. That is, as long as the points lasted.
                He developed all the 3ph and other ac electricity principles we use today.

                Read Nikola teslas life journal. It is very interesting. There is a lot of fictional crap wrote about him too thou that is a really big turn off. And they say his mother was more intelligent than him.

                Westinghouse was in it for the money, Tesla wanted to give the world free power. When Westinghouse determined the tower Tesla was building in New York was a power transmission tower he withdrew funding. They say Tesla had some ionized-stream energy weapons that the USA is still trying to develop.

                Why did I type all this? to initiate a educational purpose to all who are interested, make them open a book and read.

                David

                Comment


                • #9
                  <font face="Verdana, Arial" size="2">Originally posted by ibewgypsie:
                  3ph: Lightning has so much energy a small ground wire evaporates.</font>
                  The size of the ground wire is almost irrevilant when it comes to lightning. All the lightning uses the ground wire for is a path of least resistance.

                  Once a full discharge occurs, the ground conductor will most likely evaporate as you say, but a plasma bridge forms providing a direct path for the current to flow. The initial conductor is just a guide to set off the initial formation of the plasma bridge.

                  It's the same principal as shooting a little rocket with a super thin conducter into an electrical cloud.. The current discharge though the tiny thin wire triggers a full blown discharge creating a plasma bridge (the plasma is conductive just like a massive ground wire would be).

                  All the ground wire does, is provide an initial pathway for the discharge to occur. It's not designed to carry the current of lightning, it's designed to stear it away from someone holding that electric drill.

                  -Adrian

                  Comment


                  • #10
                    <font face="Verdana, Arial" size="2">Originally posted by Jim Hubbell:
                    In reading this thread I am puzzled by an explaination for 110/220vac at the service entrance. Namely, "inverted sine waves" on the 120vac from neutral to L1 and L2 respectivly. Since L1 and L2 are the ends of of the secondary of the power transformer and "neutral" is a center tap, how is it possible to have a positive potential on one half of a winding and a negative potential in the other half? As I see it, the potential, during one half cycle, could be L1 plus and L2 negative. L1 pos. to neutral and neutral pos. to L2. Very similar to a voltage divider. Please enlighten me as to where I am wrong. Thanks</font>



                    I'm Not sure this will enlighten you, but if you look at that A/C sine wave and consider it L1, L2 starts at 180 degrees and thus produces the inverted sine wave of L1.

                    -Adrian

                    Comment


                    • #11
                      Jim:

                      3Ph posted a scope pictorial representation of what 120 power is actually doing, Switching polarity from positive to negative.
                      Other side of the 120 is exact reverse polarity in synch. When you measure the 220 legs you have actually 2 110/120 legs out of synch 180 degrees to where they actual power between them is 220/240. Measure from either to the neutral and you get 110/120.

                      3phase power, the legs are 120 degrees out of synch. Perfection. Much more effiecient method of motor-pole propulsion. More like a stepper motor with the motor drive being the power pulses 120 degrees out of synch with each other.

                      You can feel the Pulsating Power in a electrical power plant, as you pass the generators and the Spinning magnetic poles are passing any steel/iron pulses with the magnetic waves. I have carried a small 4" cresent wrench for decades. The first time I walked by a generator it felt like I had a frog in my pocket with it jumping. Scared the be-Jesus out of me.

                      Communication is my poor skill, I hope I helped some.

                      David

                      Comment


                      • #12

                        A single phase A/C electric motor is like running a 3-cylinder engine on one cylinder. A 3 phase A/C electric motor is like running on all 3-cylinders.



                        As you can see, you get 3 peak to peak pulses, but more imporntatly, you get a much higher duty cycle which is where the real power of 3 phase comes in.

                        -Adrian

                        Comment


                        • #13
                          For the sake of discussion consider L1 and L2 to be the ends of a conductor (wire) that is in an alternating magnetic field. Let us also have a conductor connected to the center of this wire at a point we will call neutral. It is neutral because it is grounded. (Any one of our three terminals could be grounded and therefore neutral.) So as to be able to see what is happening a voltmeter is connected to L1 and neutral and likewise to L2 and neutral.
                          Since the sine wave diagram shows time on the X axis, and potential on the Y axis, let us consider a time between 0 and 90 degrees. There will be a potential induced in the L1, L2 wire. Each voltmeter will show آ½ the total potential. Since it may only be at one point on the wave at any given time there is no phase shift.
                          If it was possible to shift, or create, a phase by tapping a transformer winding we might tap it in three points and enjoy three-phase power in our shops!
                          Jim

                          Comment


                          • #14
                            Jim:

                            You are short the "triggering" 120 degree cycles they use to "time" the generators in a power plant. They synchronize the phase waveform to the transmission line via a exciter running into the generators.

                            Utilizing a 180 degree waveform (singlephase) it is very difficult to create three degree 120 waveforms. A 180 degree is actually "one" leg of the transmission lines running two transformer coils with alternate ends coming out and the center tap tied to neutral-ground.

                            What is pretty wild, using two legs of transmission lines and two transformers getting three legs out. This induces a high voltage unbalanced leg that varies on the secondary from 90 volts to 180. It is commonly called the "stinger" leg.
                            This commonly creates electrical noise that is radio frequency transmitted to affect everything around it. Dupont had a center leg like this that was grounded. To get all three phases you wired to all three legs, but seeing the center tap with a pipe plug in the fuse holder gave me the willies.

                            OUR way of generating 3 phase power in our home shops five years ago I would have said would not work. It is a wierd method altering the 180 degree waveform into longer pulses using a motor and a capacitor/resistor to lengthen the waveform pulses. It is still a strange method that goes against what I was taught at a early age. It works.

                            I have a 10hp motor tied to a 3 pole dissconnect. A 120 volt motor spins it up to speed then the power is removed from it and the single phase power slammed to it. The extra leg with the rotating fields inside the motor generates another pulse on the third leg. So for simple applications all you really need to generate 3ph power is a large 3ph motor and some way to spin it up. Once it is rolling the single phase input to it keeps it rolling. Not a true 3ph, but it starts 3ph motors and powers them. I'd like to see the output of it on a scope. A 3rd wobbly weak power pulse I am sure.

                            [This message has been edited by ibewgypsie (edited 05-10-2005).]

                            Comment


                            • #15
                              <font face="Verdana, Arial" size="2">I'd like to see the output of it on a scope. A 3rd wobbly weak power pulse I am sure.</font>
                              On my phase converter, a DMM doesn even BEGIN to describe how wild the generated leg really is. The dmm indicates an RMS voltage imbalance (line-to-line, no load) of about 10V after I got all my capacitors set up. I couldn't hook my scope line-to-line for fear of damaging it, so I had to hook it line-to-neutral, which should theoretically produce a waveform with an amplitude of +/- ~170V (120V RMS). Even with my scope probe set to 10x, I still couldn't effectively measure the entire waveform, but it looked ugly. I think I could've made a voltage divider circuit to measure it, but didn't spend the time. Idler motor sounds good though :-)

                              Chad

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