Grounding Transformer Output

  • Thread starter Bob Dannenfelser
  • Start date
I would recommend that you ground your transformer. You may also be required to by your local electrical code. Now considering the interference question, your 75 VAC is actually grounded to an extent through the circuit distributed capacitance(all AC circuits are). But grounding by itself does not necessarily reduce interference. If you are using shielding against electrostatic interference(capacitive coupling), solid grounding should help as it will makes your interference signal solidly referenced to ground as is the shield thus providing better protection. If your interference is inductive(magnetic coupling), grounding will not help. Bill Mostia =========================================== William(Bill) L. Mostia, Jr. PE Independent I &E Consultant WLM Engineering Co. P.O. Box 1129 Kemah, TX 77565 [email protected] 281-334-3169 These opinions are my own and are offered on the basis of Caveat Emptor.
 
>By grounding the neutral you are lowering the impedance of the supply back to the power plant. < I would be interested in some further explanation of this statement. Bill Mostia =========================================== William(Bill) L. Mostia, Jr. PE Independent I &E Consultant WLM Engineering Co. P.O. Box 1129 Kemah, TX 77565 [email protected] 281-334-3169
 
Curt . . . What state do you work in? I dread starting stuff up in Chicago, the Union shop steward hands out lists of acceptable restaurants that we can patronize (one's that were not built with scab labor). The fact is that we run two union crews on every job - 2 shifts to get work done - a third shift of engineers and techs show up after the second shift of union electricians leave and we are gone an hour before the first shift shows back up. We review all the work and make corrections or outline changes that we want them to make (all black wires in an encoder cable are the same aren't they?). The two different shifts of union crews are always griping about each other getting too much work done! We call the workers on our third shift "the elves". Our goal isn't to take their jobs . . . it is to keep our start-up on schedule and on budget without any body getting hurt or blowing up any drives / motors / controllers. I run into a good union crew just often enough to keep me from losing my sanity when doing machine installations. We run a non-union panel shop and our systems are second to none. Our guys know how to deal with EMI issues, various fieldbus technologies, low voltage and high voltage power distribution systems, etc. We are inspected quarterly by UL and there are no restrictions on qualifications for our panelshop staff except those restrictions that we as the employer place on them. We have a vested interest in doing a good job - our reputation and future growth in this industry. Ken
 
R

Ralph Mackiewicz

Indeed. The license does not make someone qualified. I think that the important issue is personal knowledge and experience. You would not believe the shoddy work that a "licensed" electrician did in my basement that I must now fix with a "qualified" electrician. And this is simple stuff compared to an industrial control cabinet. That license was no more a guarantee of quality electrical work than the cosmetologist's license is that I'll get a decent hair cut at a local hair salon or that the licensed driver in the car next to me is a good driver. Quality of personal skill and capability cannot be effectively regulated or assured via licensing. Regards, Ralph Mackiewicz SISCO, Inc.
 
B

Blunier, Mark

I'm curious as to whether the poor job was to to the electrician being sloppy and not following the prints, not knowledgeable enough to follow the prints, or because the prints were wrong or non-existent. Was the "garage shop" supposed to wire it up, or do the engineers job of designing it too? Mark Any opinions expressed in this message are not necessarily those of the company.
 
C
> What state do you work in? I dread starting stuff up in Chicago, the Union > shop steward hands out lists of acceptable restaurants that we can patronize > (one's that were not built with scab labor). We work in MN mostly. > The fact is that we run two union crews on every job - 2 shifts to get work > done - a third shift of engineers and techs show up after the second shift > of union electricians leave and we are gone an hour before the first shift > shows back up. We review all the work and make corrections or outline > changes that we want them to make (all black wires in an encoder cable are > the same aren't they?). The two different shifts of union crews are always > griping about each other getting too much work done! We call the workers on > our third shift "the elves". Our goal isn't to take their jobs . . . it is > to keep our start-up on schedule and on budget without any body getting hurt > or blowing up any drives / motors / controllers. > > I run into a good union crew just often enough to keep me from losing my > sanity when doing machine installations. There's no way we could afford to run that way. I'm not even worried about whether they are unionized or not. The state laws should not unjustly favor any one business interest And laws that prevent correct installations are broken. The law is supposed to serve the people not hold them up. It is an intolerable situation. And I don't even know if the electricians are union, non-union, or it's just somebody's brother in law on the licensing board, the cozy relationship smells. Standards should be standards and any method that meets them should be legal. I don't think the present law is good for the public, but it's fantastic for the electricians. Regards cww
 
J

Joe Jansen/ENGR/HQ/KEMET/US

I once worked with a licensed plant electrician who made the most nightmarish wiring schemes imaginable. Usually he would use wire nuts in place of terminals, and if a wire needed to be moved, and wouldn't quite reach by stretching it across the front of everything, he would just wire nut an extra 6 inches or so of wire. Throughout the plant, they would average a panel fire once or twice a year, with a major one about every two years. (Major defines as needing to replace an entire 2+ door, 72" tall panel). Any time anyone would say anything to him, he would get belligerent and say things like "Well, I have the license, not you." or "I won't tell you how to do your job, and you don't tell me how to do mine" and the like, sprinkled with your favorite expletives. He basically had a license to be arrogant and blame anyone else for the electrical problems in the plant. Since he refused to document anything during the 15+ years at the plant, the owner was afraid to get rid of him because then nobody would know how the plant was wired. The local inspector was simply pushed around the plant through the 2 or 3 areas that were OK, and the rest was of the 'inspection' was conducted at the pub across the street. Note that the inspector was licensed as well. I do not know what anyone else's experience is, but from what I have seen with this and the 'licensed' union electrician in Illinois who was DIRECTLY responsible for nailing me with 480VAC because of his wiring practices (no discipline, because he was in the union and I was a contractor), I have found that 'licensed' does not automatically mean 'competent' by any means. --Joe Jansen
 
R

Robert WIlber [Licensed Philadelphia ele

True, "union" or licensed don't automatically mean competent or skilled, but 'unlicensed' absolutely means unable or unwilling to meet minimum criteria for recognition by some hopefully unbiased external authority.

--Robert Wilber [Licensed Philadelphia Electrician]
 
Top