Electrical Troubleshooting

hiiii
Sorry this is not PLC related question


I work as Electrician in a compnay that is like 100 yrs old.
There are no prints for most of the machine.
It is very hard to trace wiring inside the cabinet by pulling wire because that mess up the look of whole cabinet/panel. Also, wire are short in length to pull.

HOW DO I TROUBLESHOOT WITHOUT PULLING WIRE AND WITHOUT PRINTS?

Join the elevator trade...thats our specalty. Everybody seems to swipe prints...

Anyway. About the only thing you can do is get a bellset, and legal size pad and start ring-en them wires, and devices.

Draw a layout first and check off the contacts and terminals as you go thorugh it. After a few hours you'll start to see what will look like a ladder diagram.. then peice it togeather..

Long haul..but it might be worth it in the long run.

That sounds like a pretty badly done panel.
Use a multimeter where needed, a stack of rough paper (always recycle paper), and some pens and you can spend a whole day tracing the wiring layouts.
Good luck on that!

regards
Sherine T.

HEMANG,

In reply to your PM...

This isnt easy. The place to start is to ring out the field devices (limits buttons lights motors etc) first. and mark them on a drawing to the controller terminals.

Panel drawings are always shown with the power off. So disconect the main power and ring it will a bellset. I have all kinds of fancy equipment but my 6 volt battery and bell work best for this.

I'm presuming that each device (relay, timer etc) has a name associated with it. If not then lable them R1, R2, T1 etc.. Same goes for the terminals. Each relay should have a contact or terminal point that will be connect to the contact by a shunt, and coil leads. Newer relays have pins that are marked 1,2,3 and so on. The relay sockets should also have the same markings.

for example a typ KH relay (4 pole form C) will have three terminal for each pole pole 1: 9=common, 5= N/0, 1=N/C. and so on. 13 & 14 are for the coil. Mark them on your drawing like so:

    R5        R5        R10 

*---] [---+---]/[-------(  )----*??

   5   9  |  9   1     13  14

          |

          |   R10        R20  

          +---] [-------(  )----*?? 

             9   5     13   14 

You have to place a lead on the bellset on one terminal on the strip and start ringing all the other devices. when you get a ring, check off the terminal on that device and draw a circuit from the terminal to it. Then go to the other side of the device and start ringing untill you get another hit..and so on. As you go along there will be fewer and fewer terminals and devices to check, so it will start to go faster.

You'll likely have to re-draw a rung a few times over and make changes so use a pencil and have an eraser at the ready.

I dont know how big your panel is but some elevators have hundreds of relays.. I've seen this process take up to a week. On a small panel you may get it in a day or so.

There's no easy answer. But once your able to create a workable drawing, it'll pay for it'self 10 fold over time.

Good luck with it.

Just in case

Not all electricians are familiar with using wire tracers, what Mike called a bellset has been around along time. You see phone linemen use them all the time.

Nowadays they make a variety of tone/digital tracers.
We are all familiar with the Amprobe brand: http://www.amprobe.com/cgi-bin/pdc/searchprod.cgi?category=66&type=elec&tid=1&action=search

http://www.extech.com/instrument/categories/cable/cable.html

In this case the idea would be to goto say a terminal and connect the tone generator to a wire/terminal then you could trace to the device....or vice versa.

IF the wires are not numbered then use numbers to mark them AND WRITE WHAT NUMBER goes to what device...if necessary mark the wire to match a device...LS1=Limit switch 1, PE1=Photoeye 1.

If possible obtain one of those cheap label printers from OfficeMax or Staples and apply labels on or at devices...ie LS1 at or near Limit Switch 1.
http://www.officemax.com/max/soluti...sp?BV_UseBVCookie=yes&expansionOID=-536879710

Even if you dont develop a drawing of the machine/system if you KNOW which wires goto what component the troubleshooting will be easier. Its even better if you can develop a drawing.

Another suggestion is to have your "NOTES" or drawings laminated and affix them to inside of panel plus keep copies in a file cabinet.

Personally, I like using the bell set because it typically wont ring, or will ring very week through a relay coil. Some of the tracers will, and might send you off in the wrong direction. The other issue is that the bellset (used 4 inch edwards bell) is LOUD and un mistakeable. That will come in handy when working on a plant floor full of ambeint noise and all sorts of other electronic beepers and buzzers etc going off..

It's just a preference..

My guess is that if you dont know the machine well and have no documentation, your someday gonna have to do this. If you dont have the time right now, all you can do is to take a close look at all the devices with a flashlight and magnifier (relays, switches etc.) and see if you can see someting amiss like a burnt contact, broken shunt etc..You might get lucky.

I wasnt stating a preference on any type of wire tracer. I was providing information "in case" the person wasnt familiar with what you meant by bellset...not many electricians use bellsets. I know many wouldnt know what you mean.

Many new model tracers also incoporate leds to display signal strength so issues like feed thru a coil would be detected by a low signal.

Some models allow connection to "live" circuits.

I have used a variety of different brands/type tracers without major problems but like any "tool" you have to get familiar with it.

No argument from me Ron. I've been using a bellset for so long..and every body around me..that it wouldnt naturally occur to me that some wouldnt know what I was talking about...

I'm kinda stuck in a groove, have a few of them neat tracers your talking about but always seem to grab the bellset.

LOL I always wondered what the old timers meant by "ringing out the circuit". I thought it meant creating a wire ring (closed circuit) back to the ohm meter.

Thanks guys! That one goes in the toolbox AND the trivia book!

TM

start NOW

HOW DO I TROUBLESHOOT WITHOUT PULLING WIRE AND WITHOUT PRINTS?

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HEMANG use the tools Ron and Mike are talking about and every time you trace out a circuit make your on print. Before long you will have better prints than what you`ve got now.
As for YOU Timothy

LOL I always wondered what the old timers meant by "ringing out the circuit"

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I`ll have you know some off us on this site are not OLD TIMERS WE`RE YOUNG MEN TRAPPED IN AN OLD MANS BODY

HEMANG,

I have done some troubleshooting without having drawings. It all depends on what the problem is. If it happens to be a tripped breaker or a blown fuse, then it is easier to find a shorted or grounded circuit than to make new drawings. To find a shorted circuit, with the power disconnected or turned off, put an ohmmeter across the control power supply leads and measure the resistance. If it is 0 or approximately 0, then you probably have a short. You can find where this short is by systematically isolating each section of the cabinet. For example if there are several branch fuses, then open each one and re-check the resistance across the control power leads. When the resistance climbs to some value above 0 (usually 25 to 500 ohmns) then you have found the short and can make repairs. If there are no fuses you will need to disconnect the "hot" leads one at a time, rechecking with the meter after each disconnection.

Greetings!
I too am a plant maintenance electrician, and the majority of the equipment I service is built out of this country and is "dated". But one thing you might try first is aquiring the original schematics from the manufacturer. I have had suprising success at locating original documentation over the web. Admittedly most of the time controls have had modifications made over the years but it is a very good place to start. It is interesting to see the original intent vs the current operation of manufactured controls.
Also, There is also the option (if you have the intestional fortitude )to update the existing controls. This is my personal favorite method. It really makes the installation more efficient in terms of trouble shooting and downtime. It also tends to make the pencil pushers squirm when you have a system cut to shreads in the floor. BUT!!! I do not recommend this for the inexperienced or weak of heart!
horned toad

THANKS TO ALL OF U FOR YOOUR TIME AND EFFORT

I WILL TRY TO WORK ON UR ADVISE WHEN APPROPRIATE AND ALLOWED TO DO SO.

I GOT MYESLF A BOOK 'ELECTRONIC TROUBLESHOOTING ' FROM LIBRARY
IT MIGHT HELP U TOO
BOOK COVERS:
1) PRINCIPLE OF TROUBLESHOOTING
2) TROUBLESHOOTING GUIDE FOR MOTORS GENERATORS, ELECTRICAL/INDUSTRIAL CONTROLS,DIGITAL CIRCUITS,BIOMEDICAL,MICRPPROCESSOR, RADIO& TV


I AM ENGINEER WORKING AS ELECTRICIAN .

BOOK COVERS:
1) PRINCIPLE OF TROUBLESHOOTING
2) TROUBLESHOOTING GUIDE FOR MOTORS GENERATORS, ELECTRICAL/INDUSTRIAL CONTROLS,DIGITAL CIRCUITS,BIOMEDICAL,MICRPPROCESSOR, RADIO& TV


I AM ENGINEER WORKING AS ELECTRICIAN .

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Hmm...a book of such values. Maybe I should try heading back to my old school and search for it instead of the public library. The reference section covers more of business stuff then electrical books.
In many cases from where I'm located, engineer and electrician/technician have not much of the difference. Everyone gets their hands down and dirty, making machines come to life.

regards
Sherine T.