"I CAN SMELL THE BURNING!!!" | Extended Fault Finding Vlog | Electrician In London
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- čas přidán 24. 02. 2021
- In this video, I'm called out to an industrial site to do fault finding.
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I like your videos, no drama, no waffle, just straight to the point.
You are good Delroy. It is great to see you work through all these issues and get a result. The client was very happy with you.
Great vid Del.. was nice to see the updates from problem solving to the solution, top stuff 👍
D.O.L These units are called direct online starters and have a adjustable overload.
Great video Dellroy 😀🙂
Love your honesty in your vids Delroy, I'm retired now but still in the game watching you, so thanks for that😀
Electricians should come with Sherlock Holmes hats and pipes to each job. Seems to me they are always having to solve mysteries.
Yep, fault finding is a lot of sleuthing and deducting! Or diagnosing maybe. "What causes can lead to these specific symptoms?" and then checking possible causes one by one. I see that a lot on the internet, where someone posts a fault description and people randomly shoot suggestions without even bothering to read properly.
"My RCD keeps tripping whenever I plug in something big!"
"Well, have you checked that everything's earthed correctly?"
Dude, tripping on random loads is a textbook symptom of a N-E fault! Grab your megger and start disconnecting neutrals!
Ages to find a fault and 10 minutes to fix it😂👍🏻
@@markgilder9990 Car mechanics are the same. Took half a year and at least five garages to find an intermittent fault on my parents' van and ten minutes to fix it temporarily. The permanent fix was a little more involved because a wiring loom had to be replaced but it was free because their local garage was embarassed they hadn't found the fault before. A connector between two wiring looms had gone intermittent, probably due to corrosion, cutting power to the fuel shutoff valve, causing the engine to cut out.
Good work Delroy, nice to see when you get things working again.👍🏼
Nice job at problem solving Delroy. I'm sure the client is thrilled to be back in production.
Love the videos Delroy, great work....👍
Love it when a plan comes together.😎
Thanks, Delroy I'm on a problem a bit like this one - you've given me a good idea on how to fix it. Cheers and Happy New Year.
nice one. learnt lots there about the reality of fault finding and the different types of mcbs!
Good video again .You want to get the starter back on soon though.For overload protection and correct motor connection etc
The motor and control is a standard industrial installation, the motor runs a vacuum pump that has sliding vain's in it and inlet and outlet valves, the noise of the motor is perfectly normal and sound ok, it is a standard three phase induction motor that only runs on star has it only has three conductor's, there would be six conductors if it was wired in star/delta, being a three phase motor it don't require a capacitor to run or start - that is only required for certain types of single phase 230v motors. The control unit has a contactor/overload unit which is set to the motor full load running current, the inrush current is limited by the electronics on the LHS of the controller using soft start technology. I notice Del was testing for voltage not only between the earth and phase conductors, but also on the outgoing side of the mains isolator with the isolator in the off position, it is normal for the mains supply to feed in from the top but on some controllers like that they can feed in from the bottom due to the other components within in it - best practise is to test both side of an isolator to make sure of the incoming mains voltage. With that type of controller the manufacturer will not do a repair they will only supply you with a suitable replacement. I am a maintenance manager at a large wood furniture manufacture with several type of large machines including motor/vacuum pump like in this video. I hope this helps for people to understand better.
Thanks Mark.
Thats correct mark , you have lost the overcurrent protection by removing the old starter . If there was an overload situation the motor would burn out before the mcb tripped , so needs changing soon as possible . The isolator del fitted doesn't like making or breaking the starting current which direct on line is roughly 6 times the rated motor current .
Excellent explination on c type and dtype mcb for motor, thanks del...
Hi delroy great content as usual as an appliance engineer I still learnt some thing 👍🏿
Red is On, Green is Off in New Zealand. Although I have seen European equipment with the exact opposite colouring. Green On, Red Off. That unit looks like an electronic version of a star delta switch. Job sorted. Good work Delroy.
Top man, great work
D type is 20 x MCB rating. If you fit 32A it is 640A. You have to check eartch loop impedance. If it is lower than 640A it is dangerous situation. You shouldn't just fit D and hope it works.
Also considering it's changing the designers OCPD for Type D; I'd disregard the BS7671 table and go with the manufacturers datasheet Zs and mark it on the paper work.
As an adult learner is this correct then. The Cmin factor is 230 x 0.95 = 218.5 volts, therefore to calculate Zs: 218.5 / 640 (Ia) = Zs.=0.34 Ohms?
@@no_short_circuit i think one way to do it would be to find the impedance of 1 phase and multiply by the square root of 3? Then use ohms law to find the prospective fault current? I might be completely wrong as it has been awhile, but if the run was roughly 20meters of 6mm then a fault current would atleast be potentially over a thousand amps. Again, i might be completely way off and maybe an engineer could correct me.
You can get dedicated inrush current limiters for motors!
You have to get the right one for the wattage the motor has and some even can be adjusted for the current range and ramp up time!
They come as din-rail mountable devices and are also called softstarters.
glad you saw it through and took us with :)
to me Del its looks like its a VSD starter and the wire burnt is going through the overload... very interesting video Del and a good job by you in sorting it out... defo a loose connection the cause of it...
Just brilliant the care and thought taken Del, and the way you put this together was superb . Large motors like that need a soft start (Vfds or Vsd) to smooth the current/frequency or voltage draw (their can be several types including combination one) and ensure the motor gets up to optimal speed. It will need replacing sooner rather than later - otherwise the danger is it could result in permanent damage to the motor. I would check the motor plate ratings as well to give you more information. Hope you and the family are well.
They don't do any smoothing, it's just current and torque limiting
@@sdgelectronics thanks wrong choice of words not a power-quality clean-up but a limited draw.
You can also use the old way of starting using the Star/Delta way, i.e. start in Delta - run in Star, this would limit the inrush starting current, all you would need is 3 contactors and a timer.
"the current situation" ⚡ 👍
Great explanation Del, thanks for sharing. It's really fantastic that you being a time served electrician can share your knowledge and in the process educate us. 👍🏽
Zs could be an issue with the d type mcb. Deffo worth checking the R1+R2 values and taking approiate steps to achieve the required disconnection times. Great video though.
one thing to look out for when fitting a D type is that the earth loop impedence reading needs to be very low to pass
Hi I'm a student. Why is this? I love learning about everything so more information on this would be wicked or even a website or something in the regs or osg
@@JaysScript check osg for max zs values between different mcbs’s. Basically a type D needs around 20 times the rated current to trip against the 10 times for the original type C. This means a greater current is required to meet the disconnection times which is achieved by a lower zs value. ( I=V/R) current being inversely proportional to the resistance. I might be quoting the wrong figures off the top of my head but I think I’ve got the theory right !! 😂👍 If you’re an electrical student wanting to learn I’d research the other safety aspects of replacing a DOL starter with a switch that contains no overload or a no voltage regulator for the motor, and possibly the absence of a contactor for switching heavier loads too 👍
@@lammy2304 Thanks Lammy! Cleared it all up for me there bud. It now makes sense to me so appreciate that.
Could this possibly mean that Delboy should've been a bit more careful when going for a type d. There could be loose connection etc somewhere that could cause a high Zs value hence why it tripped the type c but surely that doesn't mean going straight for a type d is the best option.
@@JaysScript Delboy !!! Seems fitting doesn’t it 😂 To be fair lots of factors could of been at play and in real life scenarios like this where supplies are limited but the customers demands are high, it’s up to the skilled individual to decide what’s right there and then and to what standard knowing how temporary the fix is. It’s easy to sit and watch and judge from a sofa with high ethics until it’s you with the issue to solve ! As you said loose connection could be one but the high resistance would be at the termination causing the overheated cable. The zs you referred to technically no as this is a fault path. Ideally a few things could of been checked that a type D would either ignore or let worsen to the point of putting persons or property in danger. But as I said before, in a real life scenario an educated temp fix should be ok. Think of it as a spare wheel on a car - you wouldn’t normally drive around with a smaller tyre that doesn’t match the others or suited for the speed of the vehicle, but as a temporary fix to get you where you need to be it’s fine ! 👍
The only other way out of that one would be a very large start/run capacitor to deal with the surge of current
Isn't this a classic example of a star-delta arrangement? The star stage approx one third of current to start the motor to reduce in-rush then switching over to delta to allow operating current once momentum is overcome?
Nice video 👌
Well done Del . Honest, on the job sparkying. Fault finding is a challenge .
@Eastway Electrical I have a question you do not have to answer if you do not want too should a shaver socket be wired into a fused spur with a 3amp fuse. I have 2.5mm twin and earth running from a double socket into a junction box. Then one 2.5mm twin and earth going from the junction box going into a 3amp fused spur for a bathroom heater. And another one from the junction box into a fused spur again 3amp out to a bathroom extractor fan. And a shaver socket from the junction box directly is this overloading at all the three rooms upstairs have 2 double sockets in each room.
thanks
15:24 Inlet current -- I've heard it referred to as in-rush current.
When a motor is stopped the amount of current needed to start it rotating is so high that it basically appears (to the breaker) as a short.
I think it very similar to an A/C Fan where you need to a start capacitor to get the rotor spinning and then disconnect the capacitor (like with a centrifugal switch).
Washing machine motors often use a centrifugal switch to disconnect the capacitor once the motor comes up to speed (the centrifugal force breaks the connection).
Why do motors draw so much extra current on start-up? I mean 640 amps is nuts. I have to have a 6 kw generator to run my 1 kw solar water pump when the sun doesn't shine even though the 1 kw of solar panels can start the pump at about 200 watts. Colour me confused.
The mcb should be rated appropriate to the supply cabling, 6mm, 32amp breaker(assuming a short run. That vac pump should then have an appropriate motor protective device local something like an Eaton pkzmo, near to the , soft starter or star delta starter. Once you go over 7.5kw dol starting is not a good idea
That looks like a recirculation oil vac pump too, it's going to have a fairly high inertia which will increase the starting current, in comparison to something like a big fan where the mechanical load (torque) increases as the motor approaches full speed
They do teach this in college but of course a lot of this applies to new installs. In that scenario you get a lot of the technical information up front. It is much harder doing maintenance and repair work where you are going in blind. I would be very wary of changing a C Type for a D though without confirming the design parameters. Your assessment was correct but you needed to refer to a design Engineer for ratification. Since this is a commercial building and the installation looks like it was done professionally there should have been design documentation and hopefully the company who did the design might still be available for comment.
You could get one from R/S components online worth a look at
63amp isolator has more room . No point struggling del!
We cannot see the proper torque srewdriver set to the proper Nm as indicated on the conductor (i.e. 3.2Nm), and also a proper crimper was not presented. Conductor didn't get replaced and not even contacts cleaned. No tests done.
A bit dodgey if you ask me.
Soft start is there to bring the high load up to speed without stressing motor and vacuum pump, while limiting in rush current. Could of at least had a star/delta starter.
I've always been told you should never switch loads with an isolator, next thing it'll be welded. Leave it to the control gear.
I would of checked the resistance between the windings of the motor. The starter is not a VSD or SOFT START. It is a simple direct online starter. I would expect that the motor starter also was connected to an emergency stop button that dropped out the contactor if operated. At a simple glance / the motor looks about 7.5kw - Need to check on the motor data plate. Also once he had the motor running, you should check that each of the windings L1,L2 and L3 are pretty much the same current draw.
If it is 7.5kw then * 1000 = 7500 / 400 (Nominal voltage) then divide by 3 = If wired in delta about 8 amps per phase. If wired in star then 7500/230 volts / 3 windings = 10 amps per phase - A 32 C rated MCB would be perfect. I suspect the windings on the motor are out of balance of the fan was clogged up. Need to get the DOL starter fitted or you could end up with a lump of goo
@@robertwheeler8476 Hi Robert, i would check your voltages on three phase wiring, if its DELTA the voltage is around 440 volts and no neutral, if its STAR which is normally feed to buildings its is around 415 volts with a neutral, between 2 phases it will be 415 volts, and between 1 phase and the neutral it will be 240 volts. With the correct voltage the current calculation will be different.
@@markdawson4305 Hi Mark, In the UK DELTA is 400v and Star 230v.... I.E 400*square root of 3
400V on delta and 400*square root of 3 =230v on star
meant divide 400 by square root of 3=230v
Good video. Remember B type is rated to 5x MCB rating, C 10x, D 20x. So D32 is rated to 640A startup load
Not all heroes wear capes
I thought green meant off and safe to work on. Red meant on and not safe?
That was a tough gig Delroy. Your experience and knowledge saved the day.
probably the motor controller burnt out,looks like it could be on the pcb
Probably tripping because of current inrush, looking at the original switch wired through a contactor it wired to start in star configeration then switch to delta, this allows a lower current inrush and lower voltage once the machines running . Give away is the start time and initial torque and stop time labeling
if it was a star delta contactor youd have 6 cables leaving the box,not 3
@@jan-dr1xl Old style contactors yes some of the newer ones though so all the switching internally electronically
regardless of the switching method you still require both ends of each winding at the switching device if you want star delta opertation. The box on the wall looks more like "soft start" unit.
Star delta requires the six winding ends back at the starter , you are right it must be a soft start .
Yer in the end it sounds like you're doing what you should have done and just replace the motor stating contacts, as that's where the current switching is going on. I only know as they rammed this home at technical college, (Never switch a motor direct that has a high in-rush current, unless you want bacon and eggs)
🧡🧡🧡🧡🧡🧡
Bro you don't sound sure while doing you troubleshooting,you have to test your contractor but testing it cool then energise it manually.
lots of current with loose connection's
Is spark a common label in the uk?
Yes and Australia. Spark/Sparky
@@vivalasexy thank you. In the US sparky is mostly used as a slur
Green is safe
Are you guys allowed to size OCP for motor with breaker at 250%?
I'm no expert but that motor sounds like it's caked in dust internally probably needs a good service. The bearings are probably worn and the friction is causing excess current to get it started. It probably wouldn't have tripped C type breaker when it was first installed new.
state of that hoya 😐
That company should have sent out a new unit in exchange for the old one. Typical poor customer service!!!!!!!
Industrial control panels are often built to order. Changing the contactor would have been practical on a quick turnaround basis but there could be triac control in the panel and possibly damage to one or more of those too. Clearly there are semiconductors on the circuit of some sort, you can see the heatsinks.
This shows an experienced electrician who knows his stuff for sure!! The whole place could have gone up in flames if they hadn't called when they did
Not really Mike, he clearly did no understand the equipment he was working on - and no electrician should be working on anything they don't understand. He would of been better leaving it well alone and making sure the Protective device was turned off and locked off until a suitable replacement could be find. It was clearly not running when he got there, if it was it most likely would of tripped out due to an imbalance of load.
@@markdawson4305 there's always one know-it-all troll😅
@@mikeypc3592 Please don't be ashamed I work on these things all the time, I like watching your vid's was just pointing out things from my experience.