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  • TROUBLESHOOTING

    TROUBLESHOOTING 1 fixbear updated 2 years, 1 month ago 1 Member · 5 Posts
  • TROUBLESHOOTING 2

    guest

    Member
    December 22, 2017 at 12:00 am

    I was just thinking of some of the scenarios which I’ve been in while troubleshooting electrical equipment.

     

    More often than not, my need for access to TWO test points in a circuit is restricted in some way. 

    • Whether it’s because of being somehow blocked by the unit’s enclosure,
    • whether it’s because my test leads simply won’t reach the test points,
    • whether it’s due to the type of connections that are used in the circuit…
    • or whether it’s because I’m NOT really good at standing on ONLY my head while using my hands to maneuver the test leads…with the meter awkwardly sitting sideways in the only possible place I could put it…while trying to avoid knocking it off…and while trying to see it.

     

    Of course, in the last scenario, THAT would generally ALSO include the exact moment when some duffus in the kitchen decides to drop a pan on the floor – at THE VERY MOMENT that I’m making contact with my circuit’s test points for a crucial voltage reading in a 480v circuit. TROUBLESHOOTING 3

     

    INDEED, some equipment is obviously designed by engineers who offered absolutely NO thought to the fact that their equipment WILL fail at some point. 

    I’ll spare you of the wretched thoughts I have towards engineers.

     

    Many technicians will find these austere situations as a discouragement and therefore take some alternate approach (or just make an assumption) that may lead to an improper diagnosis. I’ve seen this play out time and time again.  In those situations, ultimately some new part gets ordered, lengthy downtime ensues (while awaiting the part), the new part gets received & installed…and then the unit STILL doesn’t work.

     

    My point is that technicians must AVOID being deterred by obstacles which encumber you from performing a proper diagnosis, no matter what system or form of energy you’re working on.  Be it whether you’re dealing electricity, gas, steam, water, hydraulics, air, drainage…in a fryer, dish machine, combi-oven, HVAC unit…or a gas heater suspended fifteen feet above the floor.

     

    BY ALL MEANS, observe proper SAFETY procedure.  For instance – if another set of hands is needed to do it safely, then reschedule the service call for when you have that help.  

    For that heater, rent a lift.

     

    On the other hand, there are also many technicians out there that simply never learned (or choose not to use) proper troubleshooting practices.  He shows up on a job, get his hands in it, get only so far with it so as to reveal what’s not working.  THEN, points a crusty, grease-stained finger at it to pronounce that it needs THIS part replaced – without taking his troubleshooting endeavor to the next level. 

    AND, by the way – it so happens that he’s pressured to move on to move on to the next call because he’s booked up, so stops there because he’s seen this before and that’s what always causes it.

     

    ENTER:

    ME – to use him as an example…

     

    EXAMPLE:  He orders a gas valve for a Reznor heater (one hanging 15′ above the floor) because the he saw that the well-concealed and extremely difficult to access pilot burner was getting spark, but wouldn’t light.

     

    A heater like this:

    TROUBLESHOOTING 4

     

    More about that example in a moment.

     

    Ultimately, as a technician – YOUR intent and purpose is to troubleshoot so that you’re 100% sure that you’ve identified the exact problem so that you can fix the equipment. 

     

    NOW,   I’m not any smarter or better than anyone else. However, I’d learned years ago (and also used to teach) a six-step troubleshooting technique while in the military.  Along with that, my predecessors had pounded into my head some notion that I should VERIFY whatever diagnosis I make before replacing any parts.

    So, personally, I’m 100% sure…that I’m usually right in my diagnosis…about 100% of the time ( ±1%… TROUBLESHOOTING 5).  I DO take enough pride in my work that I’ll readily profess that my “signature of approval” is on  that equipment before I call it GOOD.

    That’s just a mindset I’ve learned.  I can’t do work which contradicts that.

    My “name” is on it.

     

    Through my forty years as being a technician in some capacity, I’ve never forgotten that ever-important step of VERIFICATION.

    I always verify – by whatever means that’s most suitable.

    • By using an ohmmeter after using a voltmeter to find that I should suspect it as faulty.
    • By temporarily jumpering it (ONLY while using proper judgment…and not leaving it that way).
    • By a visual inspection.
    • By sampling or checking the presence (or lack) of another form of energy.
    • Or other ways, based upon the situation.

     

    With that in mind, let’s go back to the tech in my example who worked on that heater.

     

    EXAMPLE:  He replaced the gas valve because the pilot wouldn’t light.  However, It STILL wouldn’t light after the valve was installed.  Further exploration proved that gas valve was INDEED supplying gas to the pilot burner, but found that it wouldn’t work because the pilot burner orifice was clogged -thereby COMPLETELY blocking gas flow for the burner.

     

    So as you can see, had this tech gone the extra step and VERIFIED his initial diagnosis by actually checking gas flow THROUGH the pilot burner, he would have discovered that his initial diagnosis (or assumption) was incorrect.  The gas valve was never at fault.

    Therefore, he would’ve simply cleaned up the pilot, reinstalled it – and the heater would have been up and running TODAY…rather that three weeks from today.

     

    One final point, which fixbear alluded to in a thread here at TechTOWN.  To quote what he said:

     

    The one thing I can say about this business,  is one must fully understand the manufacturers design, safeties,  and intended operation to be good at servicing them.  Basically,  “How does it work”.  If you can’t answer that before you start,  go back to the books. I have spent almost as much time doing research as actually being on site and repairing. 

     

    To troubleshoot properly, you’ve got to learn a unit’s system.  EVERY aspect of the equipment’s operation.  Every breath it takes.  Every moan it makes. 

    • Monitor every click… and know why it happened.
    • Listen with anticipation for an expected “click”…and explore the reason why it DIDN’T happen.
    • EVERYTHING it does from when you turn it on until you turn it off.
    • Know what it does after first turning it on…and what should happen even AFTER it’s turned off.
    • Run it through ALL modes of operation to test it, no matter how simple or mundane the problem was that you were called there to fix. 
    • LISTEN and WATCH for everything that should happen.
    • …and I could go on.

     

    – Troubleshooting isn’t simply seeing a component not working and ordering a replacement component.

    – Troubleshooting isn’t just going there and using a “shotgun” approach for identifying a problem. 

    – Troubleshooting isn’t just having experienced that problem before, so this is what the problem is.

    – Troubleshooting IS truly is a discipline which requires further study and its appropriate application in order to achieve a 100% success rate. 

     

    *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *

     

    FWIW, I went and found that six-step troubleshooting “procedure” that I learned in the military:

    Six-Step Troubleshooting Procedure

     

    You may have the job of maintaining or helping to maintain some electrical or electronic unit, subsystem, or system. Some of these jobs may be complex, but even a complex job can be broken down into simple steps. Basically, any repair of electric or electronic equipment should be done in the following order:

    1.    Symptom recognition. This is the action of recognizing some disorder or malfunction in electronic equipment.

    2.    Symptom elaboration. Obtaining a more detailed description of the trouble symptom is the purpose of this step.

    3.    Listing probable faulty functions. This step is applicable to equipment that contains more than one functional area or unit. From the information you have gathered, where could the trouble logically be located?

    4.    Localizing the faulty function. In this step you determine which of the functional units of the multiunit equipment is actually at fault.

    5.    Localizing trouble to the circuit. You will do extensive testing in this step to isolate the trouble to a specific circuit.

    6.    Failure analysis. This step is multipart. Here you determine which part is faulty, repair/replace the part, determine what caused the failure, return the equipment to its proper operating status, and record the necessary information in a recordkeeping book for other maintenance personnel in the future. While not a part of this step, the technician should reorder any parts used in repair of the faulty equipment.

     

    Sometimes you may run into difficulty in finding (or troubleshooting) the problem. Some hints that may help in your efforts are:

    Observe the equipment’s operation for any and all faults

    Check for any defective components with your eyes and nose

    Analyze the cause of the failure for a possible underlying problem

     

    Source:  Navy Electricity and Electronics Training Series (NEETS), Module 19 – The Technician’s Handbook, NETPDTC 1550/41 (Rev 4-00)

  • TROUBLESHOOTING 2

    fixbear

    Member
    December 23, 2017 at 8:57 am

    Makes me wonder how many of our brothers in this field know what safety equipment is required.

     

    Of course, in the last scenario, THAT would generally ALSO include the exact moment when some duffus in the kitchen decides to drop a pan on the floor – at THE VERY MOMENT that I’m making contact with my circuit’s test points for a crucial voltage reading in a 480v circuit

    480 and up is very dangerous.  To work on a live circuit requires a lot of planning and fore thought.  Equipment includes a insulated mat rated at 1000 volts, Face shield.  Insulated gloves rated at 1000 volts and tested monthly. Insulated tools and 4.5 ft of clearance in front of the cabinet. And sometimes a insulated arm sleeve.  Also one has to have a safety person trained in CPR and first aid watching. And you have to learn to work with one hand/arm.  I have seen 480 fireballs and what they can do. Usually happen in high humidity conditions with a dust/dirt build up in the panel.  Perfect for kitchen conditions. Makes a big hole in the panel. The explosion fireball is usually about 4 ft in diameter.  Not fun and it takes a day to com down.

     

    Many machines I’ve had to work on were placed to close to the wall to meet code. Less than 480 volts are 4 ft.  480 to 600 is 4.5 ft. When you can not even open the door panel but half way,  that’s a real problem.  24 volt control is no problem,  but when you have to work on the bottom where the high voltage is, it get’s hairy.

     

    As for gas valves;  They are built to a very high reliability standard. They have to meet AGA standards and test.  Most are  replaced mistakenly.  If it lost a diaphragm (leakage), or had a open coil,  or was out of pressure spec. Then yes, you have a bad valve. My lord, you can hear and feel it click on call. It should be a last resort item on your list.  Mostly fails are electrical control.  Plugged pilots are very common.  Following another agency that replaced a control valve makes me suspect that they did not know what they were doing.  One needs to check if the replacement is made to the same spec as the one taken out.  Found this more that once. Especially when the drop a natural gas valve in place of a propane.

  • TROUBLESHOOTING 7

    ectofix

    Member
    December 23, 2017 at 7:24 pm

    fixbear wrote:

     

    480 and up is very dangerous.  To work on a live circuit requires a lot of planning and fore thought.  Equipment includes a insulated mat rated at 1000 volts, Face shield.  Insulated gloves rated at 1000 volts and tested monthly. Insulated tools and 4.5 ft of clearance in front of the cabinet. And sometimes a insulated arm sleeve.  Also one has to have a safety person trained in CPR and first aid watching. And you have to learn to work with one hand/arm.  I have seen 480 fireballs and what they can do. Usually happen in high humidity conditions with a dust/dirt build up in the panel.  Perfect for kitchen conditions. Makes a big hole in the panel. The explosion fireball is usually about 4 ft in diameter.  Not fun and it takes a day to com down.

    Training on arc flash awareness and safety regulations stipulated by OSHA and delineated by NFPA-70E is like the elephant in the room which everyone chooses to ignore.

     

    I worked for a service company from 1998 to 2012. I worked on electrical generating equipment for twenty years prior.  THEN – along about 2010, I just happened to stumble upon the term “arc flash” while perusing the internet and said “What the @$%# is THIS!” 

    So at that point, I’ve been working on electrical equipment for over thirty years, had taught electrical theory along with the safety procedures for doing so – but I’d never heard of arc flash?  Where have I been?

     

    After some other on-line reading, I’d discovered that NFPA-70E had only just been published in 2000 (and has been revised since then).  YET, I also realized that its specified practices are difficult to enforce.  Only since I moved on to where I work now (in-house) was it brought to the forefront of my daily routine.  THERE, I’m required to wear a FRC (fire retardent clothing) uniform.

     

    YET, beyond THAT, there really isn’t emphasis on it…other that hanging some poster in the shop and making us take some short training course on it a few years ago.

    Do I have the specified safety equipment immediately available to me in the shop?

    NO.

    If it was RIGHT THERE for me to carry with me an wear, do I really want to wear that cumbersome safety equipment when I open a 480v Hobart FT900 control panel?

    NO.

    Should I?

    YES!

     

    For that matter…our large property happens to have numerous trunks of wires carrying THOUSANDS of volts into our buildings (so I’ve heard).  As such, we have a full staff of electricians (24/7) who deal with all THAT,  the power distribution panels…and many other electrical things.

    Do THEY don their prescribed safety equipment when entering a high voltage problem?

    To my knowledge…RARELY.

     

    One of my co-workers was once a practicing licensed electrician.  A smart guy, too.  A tremendous asset to our kitchen shop.  He has a story about when an apparent arc flash incident blew a metal disconnect box nearly clean of the wall, missed his head by mere inches…and his ears continued to ring until the next day.

    You’d figure that if there ever WAS a staunch proponent for observing/enforcing the procedures set forth by NFPA-70E, the HE would be the one.  RIGHT?

    NOPE.

     

    I personally realize that I’m taking a chance by NOT keeping aware of arc flash and taking appropriate precautions to avoid injury.  YET, I also am also privy to my odds on that not happening. 

    Being a victim of arc flash is like playing the lottery (like Poweball).  However, in this case – hitting the right numbers means that I’m a LOSER!

     

    Yup.  I’m guilty too.  I know better.  I open 480v-supplied control boxes very frequently.  The last one was just the day before yesterday.

    However, for the sake of expedience…and from my YEARS of practicing in a trade involving electrical equipment…it simply never occurs to me to think about the implications of arc flash.

     

    So what are the implications of encountering arc flash?

     

    The worst case scenario is…YOU DIE!

    The BEST case scenario…you live and suffer no ill affects.

    However, chances are that I will live, but incur some injury, seek medical attention and have to take some time off of work to recuperate.  From that, then I should be good because workman’s comp. and short term disability will cover for my injuries and loss of work.

     

    Well now…WAIT!

    Do I remember taking some on-line course regarding the safety procedures which I should observe per NFPA-70E?

    YES.

    Do I see a poster hanging in my shop to remind me DAILY of the safety procedures I which should observe per NFPA-70E?

    YES.

    Is the appropriate safety equipment available?

    Maybe it is, but I never asked where it is…

    Hmmm.

     

    Did my employer cover their @$$?

    Maybe so…

     

    Would workman’s comp. and short term disability still cover me?

    ???

  • TROUBLESHOOTING 7

    ectofix

    Member
    December 23, 2017 at 8:17 pm

    Although I started this thread focusing on troubleshooting, SAFETY is paramount.  Since there’s obviously more to say about arc flash, here’s some things to add to that.

     

    A video:

    Electrical Arc Flash Demonstration

    Something to read:

    OSHA regulations for arc flash safety—What does this mean for you?

  • TROUBLESHOOTING 2

    fixbear

    Member
    December 23, 2017 at 9:37 pm

    Thirty some years ago I worked for a stone quarry operation that our power came right off the transmission line (356,000 volts) unmetered to our own sub station and into the plant. Every morning the office would call the power company to tell them we were starting up.$19,000 flate rate for the day.  Inside the main building we had a 12 by 12 wireway down the main wall with dual 750 MCM feeds at 580 volts.  About 75 ft long and at least 50 fused disconnects and magnetic starters.  At the end we had a old GE multistep drum switch with auto transformers for a 500 HP motor that ran the cone crusher. It was 6 positions to start the motor in steps. Normally the operator would take about 10 to 12 min. to bring the motor up to speed.  The normal operator was out, so they put another man on it .  Well,  He grabbed the drum switch handle and flipped it all the way around to full power with no pauses.  The burn started at the drum switch and worked it’s way all the way down the wall and to the sub station.  4 men,18 hour days,  four weeks, and $400,000 in materials. Let alone the loss income and railroad contract. You would never believe what it could melt and destroy. 

     

    By the way, Quarrying falls under MSHA.. Not OHSA.  They have bigger teeth and fine workers as well as companies. Annual 8 hour safety training, issue and sign for safety gear.  And you better be wearing it when they stop in. I once got 24 tickets in one day on a machine I had just rented and set up. Competitor called the inspector when he saw me move the machine in.

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