Very noticeable over the last few decades that the basic quality of accessories, basic terminals, connectors in many cases has trended towards junk. Manufacturing standards / BS ratings / certifications as this point are almost meaningless. The certifying agencies are silent and just make excuses for the manufacturers that have shipped production to the cheapest Chinese production shop they can find.
When I worked at Motorola, we used to get field returns with the fault "Not working" on the label. I started sending every unit ( STILL not working) back out into the field with "CORRECT" written on the other side of the label. When they found they were chronically short of working replacements, the labels mysteriously started having accurate fault symptoms written on them. I got a raise for reducing the time it took to diagnose returns!
Well if one of the phases is half the voltage it could also be that it really was completely open circuit and coupled to the other two phases through whatever load was still on there (maybe even stray capacitance) and floating between the two. The resulting signal should be offset from the neutral line by roughly half the voltage because the two phases are 120 degrees apart, yeah, so the one in between differs by 60 degrees from both of those, and the cosine of 60 degrees is 1/2. I don't think high resistance could cause the voltage to dip that low on its own and keep it there without causing a fire in a couple of seconds. I once ran into something similar with some house wiring that we couldn't figure out what it did because one of the conductors had like 120V on it. Turns out it was stray capacitance from the length of cable between a couple of 2-way switches that was floating somewhere between live and neutral.
I invested in a rugged phone that has a thermal camera built in and it's great for faults like this. Also it's a sign of a good engineer to be willing to hold your hands up and say this is out of my remit and get some help. The guys that are cocky and pretend they know it all will eventually get unlucky one day and have a major accident. I've seen a 132kv breaker blow up, a 275kv CT blow up and i still get nervous about walking around HV compounds even after 18 years but that's what makes me behave safely. The day you relax is the day you should change trades.
The heat generated at the poor contact is P=I²R, so you don't need much resistance to generate a kW of heat if you've got a good flow of current. All that heat is generated right at the point of resistance, so it gets extremely toasty in a hurry.
my thought are: change and remake all four on the suspicion that the remaining three were installed with the same flaws...(i.e0 only a matter of time before one or more of the remaining three will suffer the same failure over time)? NICE VID! thanks :-)
Very noticeable over the last few decades that the basic quality of accessories, basic terminals, connectors in many cases has trended towards junk. Manufacturing standards / BS ratings / certifications as this point are almost meaningless. The certifying agencies are silent and just make excuses for the manufacturers that have shipped production to the cheapest Chinese production shop they can find.
Wago disagrees
When I worked at Motorola, we used to get field returns with the fault "Not working" on the label. I started sending every unit ( STILL not working) back out into the field with "CORRECT" written on the other side of the label. When they found they were chronically short of working replacements, the labels mysteriously started having accurate fault symptoms written on them. I got a raise for reducing the time it took to diagnose returns!
I totally get this , I can’t fix stuff if people don’t tell me the symptoms I am not a mind reader or machine operator
Well if one of the phases is half the voltage it could also be that it really was completely open circuit and coupled to the other two phases through whatever load was still on there (maybe even stray capacitance) and floating between the two. The resulting signal should be offset from the neutral line by roughly half the voltage because the two phases are 120 degrees apart, yeah, so the one in between differs by 60 degrees from both of those, and the cosine of 60 degrees is 1/2. I don't think high resistance could cause the voltage to dip that low on its own and keep it there without causing a fire in a couple of seconds. I once ran into something similar with some house wiring that we couldn't figure out what it did because one of the conductors had like 120V on it. Turns out it was stray capacitance from the length of cable between a couple of 2-way switches that was floating somewhere between live and neutral.
yeah probably just induced voltage
I invested in a rugged phone that has a thermal camera built in and it's great for faults like this. Also it's a sign of a good engineer to be willing to hold your hands up and say this is out of my remit and get some help. The guys that are cocky and pretend they know it all will eventually get unlucky one day and have a major accident. I've seen a 132kv breaker blow up, a 275kv CT blow up and i still get nervous about walking around HV compounds even after 18 years but that's what makes me behave safely. The day you relax is the day you should change trades.
Yea that’s true , was not showing g on the thermal imaging at first as when o arrived there was no load and it had all cooled down
nice vid mate. always learning new stuff on your videos.
Great explanation on your thought processes.....!!
Glad you liked it!
The heat generated at the poor contact is P=I²R, so you don't need much resistance to generate a kW of heat if you've got a good flow of current. All that heat is generated right at the point of resistance, so it gets extremely toasty in a hurry.
Thanks I never knew that maths , gonna do some messing around with that
Why won’t it zoom in?… OH FFS! 😂had me
my thought are: change and remake all four on the suspicion that the remaining three were installed with the same flaws...(i.e0 only a matter of time before one or more of the remaining three will suffer the same failure over time)?
NICE VID! thanks :-)
Excellent 👍
Thermal imaging initially may have put you in the area of the fault without accessing anything.
Did it there was no load and very little additional heat through the plastic
Excellent video Jamie
oh, what a right keruffle!
I put your videos as CPD. Much better than the boring crap the niceic put out