NanQue DZ47Z Non-Polarized DC-Breaker: Let's look into a Failed Device
Вставка
- Опубліковано 22 чер 2024
- Hi, in this video we are going to look into the NanQue DZ47Z Non-polarized DC-Breaker which failed on me last time!
On our property, all energy systems (PV, Powerwalls, etc.) are DIY. Please check my Playlists for other content. Thanks
Please consider donating to the channel if my videos helped you out in any way. We are in especially tough times and it takes a lot effort to create the content. Thank you for your kindness!
PayPal address: office@thehillside.net
YT Super Thanks: just click the heart below the video - Наука та технологія
Roland, I am going to buy a NOARK non-polarized breaker and open it up. I will take photos and video and send to you. There will be a big difference in size with the arc extinguishing chamber and metal material used at the very least. It will take me about a week or so to get a new DC breaker in, then do a tear down. The NOARK and ZJ Beny DC breaker appear to have an arc extinguishing chamber that takes up approx 1/3 of the internal volume.
Roland you asked what the material of the fixed contact could be and yes it is graphite like the carbon brushes of a universal motor. Since the contact arm has to travel further, the force of the tensioned spring is now lower, which poses the risk that a stuck contact cannot be released. That's why graphite was used instead of metal because it doesn't stick together. However, Graphite has a much higher resistance and heats up accordingly... so once again, the emergency solution could be a copper cooling strip clamped together with the incoming wire into the terminal which dissipates the heat to the outside.
Roland, the DC breaker you have uses an actual solenoid electromagnet. Electromagnets is the standard for most MCB (both AC and DC non-polarized). It can be visibly seen. It is the component that has a cylinder shape with copper winding and a little piston. This is only generating a magnetic field when an actual current is passing through. If there is no current, the electromagnet will not have a magnetic field (other than very small trace of residual magnetism on nearby nickle components).
Yeah. There was really not much visible different between this breaker and other Chines variants, either AC or DC, other then the contacts opening doble as far as what I have seen till now. I am thinking that maybe that need of more contact travel is decreasing the pressure on the contact arm when closed.
Roland, my first suspicion was right; at timestamp 3:08 there is a very small arch extinguishing chamber that is not adequete. The actual heat spots can be visibly seen starting from the arc extinguishing chamber rising up to the top orientated input terminal. Look again. The two versions of non-polarized DC breakers I use from NOARK and J Beny have much larger copper arc extinguishing chambers that extends all the way to the actual top orientated input terminal. WHat is happening in your cheap non-polarized DC breaker is consequence of overheating, where the DC arc is not efficiently being extinguished within the small (what looks like aluminium) arc chamber. This heat and plasma will deteriorate and breakdown the plastic components within the breaker, such as warping the plastic tabs and mounts for all of the components (like the contact points and bimetal strip).
Yes. You can see that heat, plasma, arc was moving on that more or less steel guiding strip on the backside to the chamber, which is really just tiny. And the material choice inside seems to be very questionable.
Roland, I now agree with topeye4202. After reviewing the video many times, the evidence supports the heat originates from being high resistance for the input terminal. Either it is wire related or actual metal terminal. Since the metal input terminal appears clean, this implicates the wire ends itself as likely culprit of high resistance. There is no evidence to indicate the arc was not being extinguished, as there is no burnt plastic internally (especially there not being any signs of overheating near the actual arc chamber itself). The only melted and damaged plastic appears to be on the external part of the top input wire terminal. So, maybe the outdoor Thai humidity moisture is wrecking havoc on your input wire terminals. I recommend you check every single external breaker that is not inside of a true weatherproof enclosure. Check the ends of wire for any evidence of water/moisture, such as bluish greenish tint for the copper wire ends. Any discoloration is going to increase the resistance of the wire which you know will increase heat.
I have something called a thermal grease which can be put on terminals to prevent corrosion and improve transition resistance. Do you think it is a good idea to use something like that on breaker terminals? I bought it for my transformer fuses to stop them from arcing there.
@@RolandW_DIYEnergyandMore Here is my understanding. The minimal tiniest amount of dielectric grease for breakers (and only the slightest amount on the wire). No other type of grease should be used. As the high temps (from resistance and electrical arc) will likely result in low viscosity of the grease that can create an internal short. Avoid using ferrule crimps for the wires going into a CLAMP terminal. Dielectric grease is not suitable for dusty environments, but is recommended to be used in corrosive (humid) environments. Ideally, dielectric grease and wire ferrule crimps should be avoided as they normally do more damage, BUT if the environment is humid or corrosive then dielectric grease will do more good. Hence why it is preferred to install the breakers inside of an actual weatherproof enclosure to avoid using dielectric grease. I stress again, do not use any other type of grease other than rated dielectric grease, and do not use the dielectric grease if in a dusty environment. Any connections that does have dielectric grease should be periodically checked every change of season (Winter/Summer) to inspect degradation, hot spots, dryness and cracking (of the grease itself). The dielectric grease will dry out and start to crack. Soon as the dielectric grease starts to dry out, it needs to be removed and then reapply the wire ends with fresh dielectric grease (the minimal amount possible).
@@Matthew_Australia Actually ferrules are just fine for clamp style terminals. Where they shouldn't be used are with screw terminals (such as electrical plugs) where you hook the wire around something.
In fact, use of ferrules in clamp terminals avoids the single most common mistake with that type of terminal that causes overheating... pushing the wire into the terminal past its insulation and clamping onto insulation in addition to the copper wire.
Ferrules are light-weight, they just corral the copper, so they are easily crushed by clamps and will generally hold better contact and reduce wire stress since stranded wire is universally used with this type of topology.
Thanks for the follow up! I'm curious: it's rated for 40A, do you know what the routine max current it would see was? The only thing I can think is "that seems like a small contact patch for high current"- maybe the contact would heat up but the base metal (... steel?) couldn't move the heat away fast enough. But I have to admit I haven't looked inside breakers too often.
Different question, what do you look for in fuses / fuse holders? I've found a few, but in general searching for DC fuses has been giving me nothing but automotive fuses, and I think asking those to break 4x their rated voltage is a bit much.
Hi. The max. current that 40A breaker saw was 25A continuous over periods of 6hrs on a nice day. Usually I do over-rate breakers by 50%. But still. With continuous currents such devices will heat up during operation.
If you are looking for DC fuses with holders, look for Solar PV fuses. Those are the DC rated ones. I will link you the fuse holder/fuses which I have ordered. Unfortunately I will only be able to install them in November, then there will be a follow up.
Holder:
th.aliexpress.com/item/1005006503836286.html?spm=a2g0o.order_list.order_list_main.4.284e52ce4Cu8lb&gatewayAdapt=glo2tha
Fuses:
th.aliexpress.com/item/1005001451833138.html?spm=a2g0o.order_list.order_list_main.6.284e52ce4Cu8lb&gatewayAdapt=glo2tha
DC fuses are Type gPV while Type gG are usually AC rated general purpose fuses. A much cheaper gG fuse can as well break DC but the voltage must be well below the rated AC voltage (1/3).
Beyond 63A you would then have to use this:
th.aliexpress.com/item/1005005032002472.html?gatewayAdapt=glo2tha
@@RolandW_DIYEnergyandMore Class T fuses for high current applications, or DC MCCB. In Australia, these two components are recommended due to high interrupting capacity (which is what is needed for large battery banks and parallel solar strings).
The contact plate where the incoming wire is clamped on caused on the outer side almost same burning marks to the white plastic of the housing as inside. That means to me the heat came mainly from screwclamp contact it self, not from the internal switching contact. Maybe the incoming wire is corroded. The wires should not be tinned or aluminum, but i guess you already know that. There are good massive copper crimps on market with a flat side which goes into the screw terminal and into the hole on the other side the stranded wire will be crimped in.....i always asked my self, are they really needed, cause directly clamp in wires make just one transition zone, with crimp there are two, but maybe failures like this and the experiences of many electricians gave this kind of crimps a right to exist....
As a alternative adding a long rectangular copper stripe between the incoming wire and the clamping surface of the terminal will act as heatsink...
It's just that 3 of 5 breakers failed within the last 3 months. On the others, I didn't see burn marks on the outside. Of course, I could be the worst talented guy who is not able to screw in a wire :)
I will use lugs before I leave now. Let's just hope the other breakers survive my absence.
@@RolandW_DIYEnergyandMore Then it must have something to do with the way they "solved" the thermal trigger, cause the room for a propper solution don't exist anymore cause of the wide contact opening. Same as I mentioned before will solve this problem: a copper stripe which acts as a heatsink ; ) ...or installing a fan (as I do) which brings fresh air and air 'circoolation' into your cabinet, cause the rated ambient temperature for this brakers is with 40 degree quite low, especially for a between others sandwiched breaker as the one who failed.
@@RolandW_DIYEnergyandMore As I mentioned somewhere, without magnets only crappy DC breakers can be constructed in this size (within reasonable price range). For bidirectional uses only fuses or bigger constructions can be reliable.
@@RolandW_DIYEnergyandMore By the way, the incoming wire acts as a heat sink too, but due to the fact here in Thailand 6 square millimeter rated wires has actually only 4 sqm and instead a thickened (thermal) insulation, this can lead to problems as you have.
@@topeye4202 yeah
I am going to delete some of my comments on this video, as I do not want to spread false or incorrct information. I was wrong about the root cause of failure related to the arc extinguishing chamber. I was also wrong to believe the solenoid electromagnet is directing the electrical arc into the arc extinguishing chamber. The electrical arc has its own magnetic field, and this magnetic field is attracted to Ferrous metals. The electrical arc is directed towards the arc extinguishing chamber due to being attracted to the Ferrous metal strips that run down towards the arc extinguishing chamber. When the air gap between the contactor pads increase the electrical arc bends/bows towards the arc extinguishing chamber, then snuffed out due to air gap, while the high temp heat and energy is dissipated across the surface area of the arc extinguishing chamber. Apologies to anyone that was misled by my misconception.
Mate. You see this to serious. In my opinion the truth is somewhere in the middle off all the debate. I only saw discoloration in the terminal area but I saw carbonated deposits only around the contact pin next to the terminal inside the device.
True, there was no arc extinguishing problem. There had been 2 disconnects but non of it caused significant thermal issues as you also have noticed.
And then there had still been the other 2 devices which failed months before this one. There was nothing to see on the outside and they went straight into the bin as I was pissed so much. So there is still a quality issue.
I think that the problem comes from humidity and corrosion, but there is no way that water can be inside the terminal. And usually the warming up of the breakers in normal operation the humidity is removed anyways.
As well i think that because according of the law of leverage, when you make two arms of a lever move twice the distance, the force on that lever is half. So the preassur on the contact will be weaker then on similarly constructed AC breaker.
Every comment is a good comment and a new clue. 😉
@@RolandW_DIYEnergyandMore Okay. I will keep the comments on the video. I forgot about your prior breakers failing. It may very well be a combination of humidity moisture and poor quality design of breaker why the high failure rate. I look forward to comparing to the inside of the NOARK DC non-polarized breaker that is still on its way to me to do a tear down. I know at least one big difference that the NOARK breakers has, and that is a larger copper arc extinguishing chamber. It wIll be interesting to see what else is different inside of a NOARK.
@@Matthew_Australia if we knew exactly what is going one within such devices, companies would stand in line and pay as big money as quality ensurance or forensic experts 😂
Roland, I have just purchased the NOARK 16A non-polarized double pole DC MCB now from ebay Australia ($44 AUD). Should I send the photos and videos of tear-down to your resort business email address?
Yes sure, thanks. Please make photos and videos from before and after disassemble, from as many sides and details you can. I will then edit it to a masterpiece :))
Carefully only open one half. The two poles might be completely independent. So you can at least keep a 1-pole afterwards. You will just have to adjust the rivets and then you can use a strong glue to hold it together.
@@RolandW_DIYEnergyandMore My video camera is capable of 4K and raw photos. I have a strong and stable tripod too. You can do what you want with the data and info. Though, I don't want my voice in the video you upload. You can mute my voice and add your own narration. I will not be talking much anyway, other than directly to you. I will try and conduct some basic tests with the MCB casing off one side to demonstrate tripping under load. I also have a thermal camera with 384x288 @ 12μm thermal sensor resolution and NETD 35mK that is rendered to a 1024×768 resolution. So, even if the optical video camera can not detect the arc clearly, the thermal video camera will be able to detect. I don't want credit or payment. I do this for you to share with others. You helped me many times, I return favour with a tear down for you.