Lincoln welder 3R3-500, Shifted output...

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TripppleP Commentator Join Date: Dec 2010 Location: Montreal Posts: 75	Lincoln welder 3R3-500, Shifted output... 08/12/2011 9:42 PM
	Hello you all. I am facing a new problem today, one of our welding machine has it output shifted to the "ground". I explain, using a multimiter with the black lead to the ground or more specifictly the 'rig body', i measured ~ 0Vdc on the + post and -55Vdc on the negative post. At first i tought that someone attached a ground lead on the positive side of the welding machine. (The machines are hard wired to a distribution network permanently install all over the rig). After looking all around the place i decided to use my head and start at the machine... And then i disconnect the positive lead from the machine and i still have the same reading... Positive lead approx. 0 Vdc to ground and minus 55 or so Vdc on the negative lead. I made sure that the supply is fine in regard to ground fault, all three phases read approx. 275Vac to groung which is OK as you know. I just decide to drop a line to you i can to the office to get the oscilloscope to see if there is something to see... One more thing who is strange is that the machine works fine if the work is not touching the body, let say on wood, so that tell me than the bridge itself is ok.. Thank you in advance. __________________ Just for fun!
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Carl Pugh Power-User Join Date: Jun 2009 Posts: 134 Good Answers: 11	#1 Re: Lincoln welder 3R3-500, Shifted output... 08/13/2011 11:23 AM
	Does this welder have a switch for negative or positive output? Is switch in the negative output position?
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JRaef Guru Join Date: Sep 2006 Location: California, USA, where the Godless live next door to God. Posts: 4665 Good Answers: 804	#2 In reply to #1 Re: Lincoln welder 3R3-500, Shifted output... 08/13/2011 1:34 PM
	Most have that switch, it represents two different methods of welding. In fact I believe Miller even has a nice white paper on their website describing when and why you use one over the other. __________________ All I every really wanted to be, was... A LUMBERJACK!.
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bubbapebi Power-User Join Date: Apr 2007 Posts: 414 Good Answers: 19	#3 In reply to #2 Re: Lincoln welder 3R3-500, Shifted output... 08/13/2011 10:57 PM
	You are correct. Here's text copied from this PDF: http://www.lincolnelectric.com/assets/en_US/Products/K1286-16/e2100.pdf Advantage Lincoln • The R3R-400 and R3R-500 produce quality, low spatter, smooth arcs without pop-outs. Line voltage fluctuations of up to ±10% are handled by the R3R compensation function to keep the output constant. • Easy to operate. Calibrated current control knob makes procedure setting simple and easy. Polarity switch, voltmeter and ammeter are standard.
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34point5 Guru Join Date: May 2010 Location: in optimism Posts: 4050 Good Answers: 130	#4 In reply to #2 Re: Lincoln welder 3R3-500, Shifted output... 08/14/2011 12:42 AM
	if all else fails ........... GA __________________ There is no sin except stupidity. (Oscar Wilde, Irish dramatist, novelist, & poet (1854 - 1900))
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garth Guru Join Date: Sep 2006 Location: NSW Australia Posts: 1101 Good Answers: 23	#5 Re: Lincoln welder 3R3-500, Shifted output... 08/14/2011 1:07 AM
	You will probably find that the positive output of the welder has faulted to ground. Usual culprit is the positive output terminal has become loose and burnt the insulation out causing a short or the terminal has twisted dragging a power bus to make contact with the casing. __________________ Dont get on to the roundabout if you dont know how to get off
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nick m Participant Join Date: May 2011 Posts: 3	#6 Re: Lincoln welder 3R3-500, Shifted output... 08/14/2011 10:23 PM
	check the revers switch maybe welded contacts with knob showing wrong position have not repaired welding units in long long time but have seen this problem once
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garth Guru Join Date: Sep 2006 Location: NSW Australia Posts: 1101 Good Answers: 23	#7 In reply to #6 Re: Lincoln welder 3R3-500, Shifted output... 08/14/2011 10:45 PM
	The switch has nothing to do with the fault. If the polarity is switched over the fault will appear on the negative connection, if care is not taken he could burn out the supply wiring. __________________ Dont get on to the roundabout if you dont know how to get off
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TripppleP Commentator Join Date: Dec 2010 Location: Montreal Posts: 75	#8 Re: Lincoln welder 3R3-500, Shifted output... 08/16/2011 1:00 AM
	Hi! I'm back sorry for the delay. No, there is no polarity reverse switch on our machines, I found that by unplugging the remote control and selecting control at 3R3, the polarity is coming back to 'normal', for now the welder( the man) can weld and the boss is happy. I will have to checked that eventually but for now i have some bigger fire to take care of... What is bugging me now, is that i can not see or understand, is what or how the reference is made to the ground. The transformer secondary is completly floating? I do not get that... __________________ Just for fun!
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34point5 (1); bubbapebi (1); Carl Pugh (1); garth (2); JRaef (1); nick m (1); TripppleP (1)

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