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 Post subject: How does110.1(I) Relate to Troubleshooting
PostPosted: Thu Jul 16, 2020 7:27 pm 
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Joined: Fri Oct 03, 2014 7:11 pm
Posts: 20
Location: Illinois
Article 110.1(I) addresses Job Safety Planning and Job Briefing. It does not differentiate between Maintenance and Repair versus routine Troubleshooting. What would a Maintenace Supervisor responsibility be as relates to a maintenace worker assigned the task of determining why a conveyor isn't running? Is a documented Job Safety Plan and Job Briefing required? 110.1(I) appears to be prescriptive. For example 110.1(I)(3)a states "A description of the job and the individual tasks". My experience is troubleshooting is more of an art form that can take different directions based on readings taken. Any thoughts on the matter would be greatly appreciated.
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 Post subject: Re: How does110.1(I) Relate to Troubleshooting
PostPosted: Mon Jul 20, 2020 1:46 pm 
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Joined: Tue Jan 19, 2010 2:35 pm
Posts: 144
I agree with you. Trouble shooting is more of an art. And thinking you can somehow do a job brief on a breakdown isn't reasonable. A machine fails for some reason and it's your job to find the reason and fix it. How can you do a job brief that? That is unless the job brief is very general in nature; you can't know what the trouble shooting person will find unless it's something that's happened before and is expected. If that's the case, then I can see a job briefing might make sense. For example, if the machine is down because it's blown a fuse (again), "here is what we need to do". However, if it's something like a burned out control transformer - a transformer that's not failed before, how do you job brief that?

Trouble shooting is by nature, a reaction to an unexpected problem. Having a perfectly good tire blowout is not something that we expect. But it does happen. If I was doing a job briefing on trouble shooting it would be jut to state that you will wear PPE, you will establish the proper boundaries and if necessary, barricade the area. And do not be afraid to ask for help. Do not venture in areas where you are not qualified. Further, to insist that no one be allowed to bother the person doing the work.

That restates to follow best practices and if he needs help, it's our expectation and is reasonable that the worker will ask for assistance.


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 Post subject: Re: How does110.1(I) Relate to Troubleshooting
PostPosted: Mon Jul 27, 2020 7:51 am 

Joined: Sun Sep 21, 2008 8:24 pm
Posts: 7
I am sorry to disagree with you but troubleshooting is definitely Not an art.

Canada Training Group has extensive experience in this as we have been teaching deductive reasoning to troubleshooters since 1981.

We drill into our students, through over a hundred troubleshooting projects on multiple realistic simulators, that deductive reasoning is definitely and absolutely a science.

Our students are unanimous that by following our protocols they will be exponentially safer.

Respectfully
Dave Smith
President
Canada Training Group


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 Post subject: Re: How does110.1(I) Relate to Troubleshooting
PostPosted: Mon Jul 27, 2020 9:53 am 
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Joined: Tue Oct 26, 2010 5:00 pm
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Location: Maple Valley, WA.
You stated, "Is a documented Job Safety Plan and Job Briefing required?". I would say that you do not need a Job Safety Plan and Job Briefing to perform basic Trouble Shooting. The more complex and higher the AF and Shock hazards may require a Job Safety Plan and Job Briefing.

However, once you find the cause of the problem, then you may need a Safety Plan and Job Briefing to repair or replace the equipment.

_________________
Robert Fuhr, P.E.; P.Eng.
PowerStudies


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 Post subject: Re: How does110.1(I) Relate to Troubleshooting
PostPosted: Mon Aug 10, 2020 6:48 am 
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Joined: Tue Jan 19, 2010 2:35 pm
Posts: 144
Perhaps the Canadian training group president is right. Providing the electrical problem follows a certain pattern or a logical path. However, sometimes the issues don't present themselves in ways that are logical.

For example, one of our team was trouble shooting a simple 120 volt fan motor. The fan had stopped and so he checked for voltage at the wiring to the motor. He measured between hot and neutral - many people mistakenly check from hot to ground. Even though he had the proper voltage, the fan did not run. He determined that he needed to check that the fan was the issue so he ran an extension cord to the fan. The fan ran fine. Using the normal source, the fan would not run (remember he had 120 volts on the circuit). What would you do with this issue?

On another trouble call, we a large generator operating a hospital. The transfer switch was in emergency and would not transfer back to normal. The normal source had the correct phasing, voltage and frequency and the time delay had timed out. The ATS was in perfect operating condition. The ATS also had an in-phase monitor which was also operating perfectly. What was the problem?


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 Post subject: Re: How does110.1(I) Relate to Troubleshooting
PostPosted: Mon Aug 10, 2020 10:12 pm 

Joined: Sun Sep 21, 2008 8:24 pm
Posts: 7
Dear Wil,

Thanks for the opportunity to explain. Before we start though, our correct name is CANADA Training Group.

Your first example, that is not a complex problem but it can appear to be. There are two problems with measuring voltage, first is do you have 120V or 120mV?

With poor lighting many techs have mistaken ghost, or phantom, voltages for real voltage. If it was a ghost voltage then that would be an open circuit on the hot.

Second, measuring between hot and neutral is valid but only if you have the load connected. Many techs forget the voltage drop formula, V=IR. If you have a high resistance connection and try to draw current through it, you will collapse the voltage at the connection and not have enough voltage at your load to make it operate.

A digital multimeter does not draw enough current to load the circuit so with a bad connection and no load, you could have full voltage until you apply the load. This is why it is important not to depend upon an open circuit voltage reading. It is why so many table saw motors get destroyed with long extension cords. No load or a light load shows full voltage; put on a big motor running through tough wood and you better hope you have thermal protection.

You also have a safety issue. If the neutral was open somewhere in the circuit, a measurement between hot and neutral would give you zero voltage even if the hot wire is energized. The danger here is your tech might touch the hot wire while they were grounded and get electrocuted. So it is important not only to test the hot to the neutral but also test hot to ground as well. It is essential your techs are doing live-dead-live tests with their meters to ensure the meter is working and the leads are good. I started my electrical training in 1975 and learned long ago to follow up the contact meter test with a tic tester. Just in case.

You did not have an open circuit on your hot or neutral as you read voltage. You did not have a short circuit as you had voltage therefore no fuse or contactor was open, or breakers tripped. You did not have an overload as your overload protection was not tripped as you had voltage at the motor. It was not an intermittent open because the fan would’ve run some of the time and certainly when he measured voltage at the motor.

I would surmise that you did not have a ghost voltage but you had a high resistance connection either on your hot or your neutral.

Taking the extension cord was a waste of time because the tech should have been able to determine that it was a high resistance fault merely by testing the voltage under load. Getting the extension cord, laying it out, connecting and disconnecting it, pulling it up and returning it to its place could easily have been 30 to 45 minutes of unnecessary downtime.

The most unreliable part of the system would be any connections, especially those right at the motor with the flexible leads, and any connection or terminal between there and the contactor supplying the motor. All it would take is one strand of wire to have voltage show up at the motor yet collapse the voltage under load.

Your tech should have interviewed the operators to see if it stopped when running or if it would not start on command? If it stopped when running, what was happening in the area when this occurred? If it would not start on command, when was the last time it started and if anything happened in the area in the meantime? They should also ask how the motor was running and if there was any odd behaviour especially smells.

Then it would be a matter of creating an ESWC. Before I do anything I recheck the voltage with my meter, then double check with my tic tester and as a triple check, with my PPE on, I short all wires, hot and neutral, to the grounded connection box. These safe work practices saved my bacon several times. After this it is a matter of checking the flex points before anything else as it is quick and easy to do.

There could be a chance that there was physical damage to the supply conductors and this should be checked after the flex points but before opening up any terminal boxes or cabinets. Damage is found by careful observation and hand checking with proper hand protection. If any of the conductor was close to something moving or a pinch point that would be suspect.

After this, it is a matter of isolating the fault, step-by-step using deductive reasoning. If the fault was at the motor it would be a 15 minute repair. Depending upon the length of the cable and the number of terminal and connection boxes it could be 30 to 60 minutes, perhaps longer if it is fed from overhead.

I have no personal experience with an ATS but if you have all of your inputs then you must have an output. Since you were on a trouble call at a hospital then the transfer switch operated to bring on the generator. Therefore, you do not have a commissioning problem, you have a maintenance problem. As the generator should have been test run once a month this would have proven that there were no commissioning problems.

When people run into problems like this careful analysis of all of your inputs usually determines that one is incorrect. If your ATS was in perfect condition then it is external to the ATS. If all of your field inputs are correct then your ATS is not in perfect condition. There is no art to this, it is sequential testing of all inputs, field wiring, and internal connections.

Your problem is in the control circuit as the power circuit has not been engaged. Again, you have no short circuit as no fuses or breakers operated so therefore an open control circuit but on the actuating side of the timer.

The first step in something like this is to get the manual and look at the schematic diagram. You want to see the control circuit scheme and isolate the problem area from the diagram. Once you have done this look at the wiring diagram to determine where everything is connected and identify the isolated problem area. Only then do you go to the machine to evaluate the isolated area and find out where your problem is.

You probably have a printed circuit board and this should be inspected for bulged capacitors, lifted traces, heating (especially around resistors), cracked components, open fuses, etc. You do not mention if a PLC is involved but if the timer has closed its contacts and nothing is happening then you have a problem on that side of the timer. Depending on the type of timer it could be internal to the timer. The schematic diagram would give you all of the conditions required to energize the coil/s that operate/s the contactor/s. It could be something as simple as a control wire pulled off when the mechanism went into emergency mode.

Electrical systems, whether power or control, are just wires running from A to Z with other inputs impacting them. There can be some extremely abstract causes of problems but in all cases deductive reasoning will find everyone of them and reasoning is a science, not art.

Thanks again, Wil, I hope you and all your kin are healthy and safe during this mess.

Respectfully
Dave Smith
President
CANADA Training Group
http://www.canada-training-group.ca


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