Transcription
Electrical Maintenanceby Dave Sayward
How to prevent that dreaded fireball in your control panel. It is simple perform routine electrical maintenance on yourequipment and catch the little problems before they turn into catastrophic disasters. You don’t have to spend big bucks forthose super expensive meters and FLIR camera’s to do this. Even pretty panels can catch on fire too.
That’s just networking equipment its just 24 VDC. Sure it’s a mess but it works for now. I wonder how these people cantry to explain what happened here. They destroyed the entire room. Maybe a little preventive work could have savethem thousands of dollars of downtime and damage. Electrical/electronic maintenance does save a lot of excuses aswell. ( Boss I do not know how it just blew up) B.S. no it did not it had all the warnings and they were ignored. That’show.
Ok I don’t have a 10,000 dollar budget for all these tools how do I do this ?1) You must have someone who is qualified to do electrical testing.2) The person must have a simple digital Multimeter (fusible type).The Digital Multimeter should have a fuse in it to stop the meter from becoming a bomb. If it does not have one I wouldn’tuse it.
Now you have fused meter and you might have to test actual live voltage you will need these as well.I know they can be a pain to use. Your dexterity drops by 50% or more, but its safety and fastly becoming the law.They saved my hands from a Arc flash incident that happened to me. My hands would have been burnt severely. Theyaren’t that expensive and you should use them every time you test over 24 volts. Betcha this guys wished he used them!
Now that I have scared the poop out of you. Know this I have been doing this for over 25 years and I am a little uneasyeverytime I test something hot or energized. So its good that you are uneasy. Pay extreme attention to what you are doing.Your testing can and will make a difference! Do it right the first time, everytime you test. Know to check a fuse? Howabout a breaker? How do you tell if something electrical is about to blow up? It usually will give you a clue. Mostelectrical Arcflash Blast’s have something in common. They are usually temperature related the hotter they get the closeryou are to an Arcflash incident. If a wire gets to hot it will turn colors first then start to bubble the insulation then reachcritical temp and boom. Here are some pictures of over heated wire.
This is a neutral wire that is loose. Notice the screw is discoloredas well. The corrective measure is cut off bad wire re strip wire reterminate make sure it is tight. That’s electrical maintenance itsnot rocket science its common sense. If you don’t correct thisnow it could get much worse. See below keep ignoring this and
This is a big problem waiting to happen. You have burnt service wires (probably loose ) if you ignore this.The 2nd pic is a total loss of the service which was 100% preventable. The little clues were there to let someone know thatyou had a big problem ready to happen. This could have been avoided !
Here is another picture of overheating of conductors on breakers. Look atthe discolored wires and the bare ground wire that has changed colors.If you don’t fix this it will fail and it might have an Arcflash along with itand burn all effected parts. It does not take a rocket scientist to figure thisout a little prevention goes a long way. A little Electrical maintenance cansave this whole situation. Notice the wires are turning black at the heatsource. (probably loose wires)Notice the neutral wire and the screw are discoloredprobably loose wire.
Here is a pic of another electrical problem. As you can tell thebreaker has been damaged by the electrical arcing. It will haveto be replaced along with correcting the burnt wire.Notice the breaker screw is missing. This should have beencorrected by the installer but now you get to fix this right this time.
Obviously both of this pics are to late to prevent catastrophic results.But as you can see these both started with small problems that grew tobig ones.
Electrical maintenance can prevent problems as you have seen. What are the 3 main reasons for VFD failures?1) Voltage Spikes (includes lightning strikes)2) Heat related Issues ( includes debris infiltration, Bug infiltrations)3) Incorrect installation.What can you do to perform electrical maintenance on a VFD?1) Visually look at it check for:A) Any discoloration of the face of the VFDB) Any unusual noisesC) Any unusual smellsD) Ensure the cooling fans are runningE) Clean the air inlet of debris and dirt.(replace or clean the filters regularly)F) Is the H.M.I. (display) working correctly?G) Is the VFD hot to the touch?H) Is the VFD enclosed?I) How is the enclosure any problems (rust, debris build up, holes, critters, insects etc )
After the visual checks on the exterior of the VFD. Now look at the wiring terminals ( this may require some PPE to protectyourself if its running.)A) look for discolored wires at the terminalsB) look for discolored screws or any evidence of overheating.C)Check cooling fans make sure they are running at their speed.D)look for any evidence of over heating or burning on electronic boards.E) If resistors are used on top or bottom get a flash light and visually inspect them.This is way to late. This VFD blew up. Wonder if preventive measures could have saved this drive?
The manufactures of fuses are making blown fuse indicators in them to help you find one that is bad. It will help someBut you need to know how to test a fuse to determine if its good or bad. Again its not rocket science just follow somesimple procedures and you can find out for sure if its good or bad.
1) Test a fuse:A) Get a digital multimeter turn it on to ohmsB) Plug your test leads into the appropriate connector’s (red one plugs into the red one V,ohms,ma. Black into the blackor common) see picture.C) You should have O.L. on the display (open Line)D) Touch the red and black lead together you should see .03 or lower ohms.E) Separate the leads the display should go back to O.L.F) If you see anything else displayed or you have to wiggle one of the leads to get it to work then you need to find adifferent digital multimeter and perform the same test on it. This not only test’s the meters leads it also performs afunction test on the meter itself. If your meter leads are not good you don’t use them. If you do Arc and Spark willbecome part of your life and they hurt a lot when you meet them.
A better meter has an auto scaling ohm function. That auto selects the range for you. These are easier. This one is aFLUKE The only meter I will endorse period. I have been shocked by cheap meters, I have had one blow up too.
Next you are going to turn the power off and test it to make sure its off. (why?) How many of you have heard of a badcircuit breaker? Lots Need I say more do not bet your life that the power is off by the position of the circuit breakershandle.3) Remove the fuse from its holder4) Put the test leads on each side of the fuse.Size of the fuse doesn’t matter. If its larger or smaller to test the fuse follow the picture. Put one lead on each side of thefuse.
Now look at the display of the meter. Slight differences can happen but this is a good illustration
Now how about testing a breaker ? Problem is that you cant just take it out easily and static test it like the fuse. NormallyYou will have to test it dynamically ( with the power on) This has some questions to ask about if you are qualified to testthis? Most employers rely on their State to determine this for them. Class 2 24 volts or less does not require a licensedperson (Electrician) to work /test these systems. If over 24 volts then The NEC code requires a trained and licensedElectrician perform the work. You should be trained on how to test an breaker by a licensed Electrician. Breakers come indifferent sizes and shape but pretty much boil into 3 different category’s 1) residential/commercial 2) Industrial/Panelmount 3) MCC type of breakers. Different voltages require different breakers. It gets complicated. From 1 phase or 2 phaseor 3 phase types of electrical systems require 1 phase or 2 phase or 3 phase breakers. Remember Breakers have mechanicalcomponents in them and can fail. There sizes range from 10,000 amps to 1 amp.Residential typeIndustrial / Panel mountMCC type
Lets face it Circuit breaker testing requires someone who is qualified to teach you. Problem is it takes time to train you totest an electrical breaker. So if your not allowed to test them you can still visually inspect them. You can look at the wiresgoing into and out of the circuit breaker and look for heat damage. If you find something not quite right notify yourelectrician that you think there might be a problem. This is a great example ! The breaker should be replaced and the wirereterminated.
Electrical maintenance will help all of your electrical devices keep running. You can even electrically tell if a motor startercontacts are bad with a meter. Same goes for PLC computers Heat is there enemy as well. If you smell something burning orsee something really hot Let somebody know asap!I here all the time ( Its not my Job!) I say yes it is ! Let someone know if you see a problem in a electrical panel, Controlpanel, VFD cabinet, PLC cabinet, Networking cabinet. ( They can catch on fire to). Remember Its up to us if we see, smell,something let some affected person know (NOW).Its not rocket science Its about dealing with a thermal run away situation. That means that the hotter it gets the conductorand the more heat happens as the resistance of the conductor goes higher. The higher the resistance the more heat isproduced. @ voltages of 120,240, or 480 it doesn’t take to much resistance to make a 480 volt uncontrolled heater.Here is an example of thermal runaway. You have a switch @ 120 vac 20 amp rated. While its on the Ohm reading of theswitch is .6 ohms which is good. After awhile the ohm reading of the switch closed goes to 10 ohms.Now ohms law helps us figure out how big of a heater this creates. 120 vac at 10 ohms 120 volts divided into 10 ohms .083 amps X 120 vac 10 watt heater. In the space of a switch box a 10 watt heater will get this warm pretty quick now themore hot it gets the more the resistance of the device gets say it jumps in resistance to 25 ohms. 120 divides into 25 .208amps x 120 volts 25 watt heater and the hotter it gets. See thermal runaway means the hotter it gets it will produce moreheat and more heat worse connection until it fails violently sometimes. The higher the voltage the faster the thermalrunway produces a uncontrolled heater. Until (BOOOMMMM).
This problem has been with us since the use of electricity. Thermal runaway is major problem with all electrical / electronicdevices. Heat related issues cause a lot of the electrical explosions and arc flash incidents. Any electrical device issusceptible to heat damage As I have said there are clues to heat damage and Thermal runaway but one must be paying alot of attention to find these clues.This can happen on fuse blocks, and even fuses themselves. Look for the evidence (heat damage) Now FLIR camera’s canhelp also The handheld digital temperature gun can do the job most of them are laser guided. Remember your looking forsomething significantly hotter then a normal one. In most cases the thermometer does a good job for about 30.00This one sells for 34.95 they actually work you have to use common sense when using them. But they work.
Now FLIR cameras are starting to come down in price they can really help you find heat related issues.Notice that it takes a FLIR picture and a normal picture of the same spot. Saving you time also if you really look the breakerAnd wire looks normal but if you put your finger on the top of the breaker it was very warm to the touch. The correctionfor this was to replace the breaker.
This customer chose not to replace this breaker it failed violently 2 weeks after this was shown to them. When it failed itdamaged the service buss bar behind the breaker the entire service had to be replaced. It cost them 2x times the itshould have if they would have taken this seriously and replaced the breaker in a timely fashion. Sometimes the customerhas to learn that this was preventable.
This wire was really loose and corrected before the heat could destroy anything. It was installed by others 2 weeks priorTo the FLIR inspection. TheCustomer couldn’t believe all of the hotspots that we uncovered he was shocked that all of the problems were caughtwhen they were small. The Plant MGR looked at the history of electrical failures in the plant. To his amazement he found 1year they had 30 k in catastrophic electrical failures. He found that what I am trying to show you that a little Electricalmaintenance goes a long ways. We had a large Muncipality contracted us to do FLIR and electrical testing for each of their22 lift stations. They have had a couple of floods at lift stations that had catastrophic failure of equipment. Since then theyhave had 0 floods in the last 5 years that we did the electrical maintenance on their stations. Electrical maintenancecatches the problems while they are easily fixed and it cost’s them a lot less than waiting for the dreaded FLOOD.
I wonder what the real cause for this failure was ? What ever it was it was it will be really expensive to repair or replace .
That’s going to be ugly! If there is any electrical down in the hole it will have to be replaced. Also make sure all electrical isturned off before you go near the water/ sewage That’s what Lockout tag out is for.
This catastrophic electrical fire was 100% preventable! Electrical maintenance could have prevented this !!!!!!!!
So a little prevention goes a long way ! Yes just like changing your oil in your car pay a little now or pay a lot latter. Most ofthe electrical catastrophic failures can be prevented and if you do a little maintenance you can correct lots of little problemsbefore they become big. I have a challenge for you. How many lift stations do you take care of 5, 10, or more? Ok no liftstations how about a MCC (motor control center) or some large electrical installation.Have someone who is qualified to perform FLIR and electrical testing on your stations. I will say that there will be at least1 small electrical problem you will find. And if you ignore it later it could become catastrophic failure that would cost atleast 10 times the cost to have someone qualified come and check your electrical system out. Just like changing your oil atregular intervals if you don’t it will cost you a lot more later.There are a lot of people that just do the FLIR inspections. However they are not qualified to do the electrical inspection.Find someone who can do both. Or Look into buying your own FLIR camera with the software. You can do your own. If youcan not afford it buy a laser guided thermometer and use it and perform your own temp scans of your control panels.I found this type of FLIR camera reconditioned for sale @ 915.00 They arecoming down in prices. They are worth every penny if you use them. They comewith software to generate reports to show your customers or yourself thatElectrical maintenance works and can save you a lot of money and time thinkingup excuses for the big boss. ( I don’t know why this happened It just blew up )I wonder how many times that one has been used. ( I’ll betcha a whole lot)Electrical maintenance works if you don’t use it just try it you will be surprised onhow much you will save by employing it.
Thank you for your time to watch this presentation.Dave Sayward
person (Electrician) to work /test these systems. If over 24 volts then The NEC code requires a trained and licensed Electrician perform the work. You should be trained on how to test an breaker by
