Inside a 125A DC circuit breaker. Unexpected arc quenching feature.
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- Опубліковано 4 жов 2024
- Initially I thought this was going to be quite a complex breaker compared to a traditional AC circuit breaker, as it's a lot harder to break a DC arc.
After initial disappointment at what appeared to be a fairly standard breaker inside with the usual bimetallic strip for detecting low level overloads and a solenoid for instant trip on very high current faults, I spotted the secret feature....
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The permanent magnet creates a Lorentz force on the arc, pulling it into the quencher where it gets elongated and cooled down by the plates, thus increasing the arc voltage to the point of extinction. But the permanent magnets mean that this device has to be used in the right polarity, or the magnets will push the arc away from the quencher instead of pulling it in!
This also holds true for DC Contactors (high current relays) which will have magnetic blowouts to help extinguish the arc when the contacts are opened, though the contactor will generally have a much lower max interruption current compared to a breaker it has to deal with the same concerns of arc after opening the contact and as such they will have a directionally as well.
Edit: May 25th 2019 - spelling
@@cmlara5333 *contactors
(The text originally said "contractors" twice. That has since been edited out, but I can't accordingly delete this comment because no one will know what the following comments are talking about. But now I have to add
* directionality
Aargh! No rest for the spelling-sensitive weary!)
MottyGlix Thanks for the correction! Never trust spellcheck at 2am in the morning.
I agree with you, but why are there no polarity indicators on the thing then???
@@cmlara5333 I knew what you meant anyway. Spellchecker is worse when you also have a drink in!
Many years ago (1990s) I designed UPS. It was impossible to get decent DC rated breakers. We used 3 pole AC breakers. One pole switched the negative. The other two poles were wired in series on the positive feed. This increasd the gap and aided arc quenching. Worked well enough. One thing that did surprise me was that none of the manufacturers would guarantee the operation of ANY breaker if it had tripped a fault. They recommended that any breaker that had tripped due to an overload was replaced. This made them no better than a fuse!
I was investigating DC contactors for a 240v ship-mounted crane. The ones I found were massively expensive, but one supplier rated their more common three phase units for use with DC when the load went through all three poles in series similar to your solution.
Magnetic quenching is VERY common on DC breakers when they need to fit into confined spaces like a din rail package. The caveat is that, unlike an AC breaker which in most situations may be top or bottom fed (back-fed in north american parlance); A DC breaker using magnetic quenching, must be fed power from a designated input terminal to ensure the arc will be shaped and drawn into the arc chute by the magnets. Thanks to Big Clive for this video!! ...even when you know how it works, it's still fascinating to see all the manufacturing variations inside these devices.
If I'm not mistaken, it is called a blowout magnet. Many DC relays use this feature to keep them small.
@Elektronik mal einfach True, but like he pointed out AC does crossover the 0 point at one time :) At our uni the professor demonstrated this issue with a 2kW DC loaded motor and pulled the blade switch with an arc about 15cm long - motor still running and lighting a piece of paper in it :)
Great vid! In the USA, larger MCB's are indeed tested under-load (called a Primary Injection test). These DC breakers are used in industrial welders, power-plants or AC to DC motor-generators. A machine called a Breaker Test Set (BTS) is used. The massive DC BTS's are powered via 3-phase 480V and weigh about a ton. It delivers adjustable power to a 3-phase selenium rectifier assembly. The output of which is injected into the breaker-under-test. The machine times how long it takes for the breaker to trip at a certain amperage. These results are compared to the manufacture's operational-curve to qualify the breaker.
Thanks, great video don't forget that your talking about Chinese Amps which are very special and of course different from our UK proper Amps;)
This is why polarity is very important with DC breakers.
If you get it wrong it blows the arc out the side of the breaker.
I saw one someone did this to on a solar installation.
Yeah, most have a big plus and minus marked...
ABB's S800S-UC appears to be polarity insensitive, which is interesting. They claim they have two arc chutes per pole (including the AC versions), so perhaps they have a different magnetic polarity on each contact/chute?
The lower voltage S200 ones do have a marked polarity.
@@someonesomewhere1240 now popular types of dc breaker are all non polarity😀we are professional manufacturer of dc breaker
thosse things usually get tested.
Some got adjustment screw. They get triggered and adjusted multiple times at the factory until in spec, then the screw gets potted.
Yes, when we are talking about life saving devices, it is not enough that "they should work". They have to work, every single one!
I think they for some devices are talking about max 1 in a million non working units.
@@friedmule5403 Regualr circuit breakers are there to protect the cable, not your life. For life saving devices there is common sense and RCD or RCCB breakers.
@@anti4354 Okay did not know that, thought that the fast reaction time and wary low current was to save people.
@@friedmule5403 If the cable fails, it quite likely ends up in flames. Flames in your wall are far from optimal.
@@namibjDerEchte LOL central heating, is a good thing:-) No I do understand but you have to be wary unlucky to get fire inside a wall, this is almost impossible if the system is build correct.
A video showing the arc blow in DC would make a great compliment to the video. Not very well known are carbon arc lamps for old movie projectors contained a bar magnet behind the reflector near the negative electrode. It's purpose was to blow the arc out from between the carbon electrodes to just above them so the reflector is not shaded by the electrode. Most people assume the arc shape is due to heat rising. While this contributes, the first sign a projector polarity is reversed is the arc points down instead of up. In a projector carbon arc lamp, the negative electrode is a short small diameter rod at the rear of the lamp and extends through the center of the reflector. To keep spatter and deposits off the reflector, the arc is blown towards the positive electrode and up, so if you ever get the chance to see one of these antique projectors operating, or find a rare photo of one operating, it will be noted the arc not only rises above the gap, but the flame tail is tilted away from the rear reflector. It is leaning directly away from the side of the bar magnet below the negative electrode behind the reflector.
Big Clive, Please try to locate a carbon arc projector lamphouse for a video and show the magnet and if possible it's setup an use.
Disclaimer, in the 1970's I had a 2nd job as a projectionist. Was lucky enough to make friends with a theater owner who still ran carbon arcs in an old style single screen large theater and was trained to run it. They even had the hand crank from before the addition of sound and the electric motor for even projection speed. This was an antique Simplex projector with the glass gearbox.
Cool, now we want to see how magnets bends arcs. Or is that ElectroBooms area of expertice?? 🤔
thats photonicinduction's expertise
try photonicinduction or applied science
lol, for sure that would be interesting, more so if they can do it visibly :)
Look no further than the old timey Jacobs Ladder.
You can search for 'fine beam tube experiment'. It is how we did it in our physics lab.
Interesting seeing the differences, but what would be even better would be seeing a DC source going through an AC breaker under fault current to see the damage it does when people inappropriately use them on a DC power system... :D
Note: I've tested that exact model and ampacity of the DC circuit breaker from aliexpress.
Try running 300 amps of current of any kind thru it.
In my case, it didn't flip (turn off) as it should have, it just smoked and stank quite a bit and then melted stuck after a while.
It's a serious issue if you ask me, since it's a safety device, so I filed a complaint to the seller, and I even got an instant refund on that case (didn't actually expect that to work but ok)
Interestingly, other MCCBs from the same seller worked OK
I usually test them at twice or all up to 5X the rated current.
That's where they're the most vulnerable. Not enough current for the electromagnet to switch, but very high current for the contacts and connections.
Of all those things, the bimetallic strip should be the one that heats the most.
If any other component heats much faster, something will melt/burn.
You should make a video with the name of the brand in the title, people will buy these thinking they are improving safety, if you have real life experience of them not working, thats a huge safety issue, that people should know about.
@@ratgreen I could.
Although, I might order another one to see if the problem is persistent.
I think people should understand that these items are not thoroughly tested, they barely even are, and it's like buying something on a garage sale, you can't blindly lean on it.
I highly recommend a HRC safety fuse in any case. Much more reliable and safer.
Never ben under the hood of a DC breaker, well done. From flooded kansas really flooded and 4 more days of storms.
Raymond Mucklow weird mechanism! Also from flooded and tornado ridden Kansas SE Corner in my case
@@Willam_J as we speak another storm front moving in.
@@trcostan same here. SE CORNER
Really cool. I was surprised at the small contacts as well but this is not a controller that cycles so if it breaks often you've got other problems that need cared for :)
We recently experienced a 127,000A phase to phase fault at work in a serious piece of gear.. Wrap your mind around that energy release.
People attempting to us AC Switches and Breakers for DC applications usually get educated rather fast. Consequences of Current flow goes up EXPONENTULLY !
Been there, done that!! What I've found, is that a capacitor in series with a diode, then a resistor in parallel with the diode to discharge the capacitor when the contacts close will allow time for the contacts to open, before the capacitor has time to charge. That makes it so there's only .7 volts across the contacts(the forward voltage drop of the diode) the instant the contacts begin to open, which gives time for the contacts to separate, before the capacitor charges to a high enough voltage to jump the gap. When the switch is closed again, the resistor slowly discharges the capacitor, without putting extra surge current through the contacts. The capacitor needs to be big enough to provide the time constant necessary to prevent arcing. The higher the current, or the slower the mechanical speed of the contacts, the larger the capacitor needs to be. The diode needs to withstand the surge current long enough for the capacitor to charge to circuit voltage. The resistor is not critical, just so it discharges the capacitor before the next time the contacts open. I do that all the time, in circuits where relays have to switch DC into inductive loads. That works for switches, breakers, and relay contacts. In my 144 volt electric truck, the breaker was buffered by the capacitors in the motor speed controller. An AC breaker worked just fine. It was rated for 400 amps!
In pdf of AC CB is printed that it can be used for DC up to some small voltage, In some i read 48V DC, i use it up to 24V DC.
That is how the relays contact work, rated on same current but lower DC voltage then AC
@@vincentrobinette1507 It will be very helpful for some of us if you could provide a simple schematic (sketch) with values of capacitance and diode rating of your solution to the arcing problem. God bless.
@@mansoorsiddique4843 I have no way to post a sketch on a reply, but, as a rule, the capacitor is sized based on the available fault current, and how fast the contacts can separate. The slower the contacts move, the larger the capacitor, The more fault current, the larger the capacitor. The resistor is based on how long it will be before the next interruption. It's only job, is to discharge the capacitor, once the contacts close. if it's a cyclic switch, like a solenoid used for a DC motor control circuit, you'll need a lower value of resistance, to make sure the capacitor is discharged quickly enough, for the next interruption.
Case and point: When I worked at a convention center as a sound technician, we had a 24 volt electric cart, that was used to haul equipment from room to room. It featured a 4 stage sliding blade throttle, with three nichrome wire resistors. When ever you let off the throttle, the first blade would draw an arc, just like striking an arc welder. I fixed that, using a 2,200 uF, 35 V electrolytic capacitor, a 6 amp epitaxial "bullet" rectifier, and a 10 Ohm, 10 watt "sand box" resistor. It completely solved the problem. If the motor was stalled, or the throttle was let up before the cart moved, it would pass a maximum of ~40 amps. On a circuit breaker, you could probably get away with 10,000 ohms, because it will have plenty of time to discharge the capacitor before the next overload. Thermal stop interrupters,(push to reset button)tend to react slowly, don't have much space between the contacts, will need a larger capacitor. The peak current pulse rating of the diode is the most relevant rating, because it's only in conduction long enough to charge the capacitor up to the supply voltage. it is, however, momentarily subjected to the full available fault current. When the contacts close again, the diode is reverse biased, and the capacitor is discharged through the diode.
HI Clive, thanks for another look at something we don't normally see inside. If you look at about 3:02, you can see that the contact gap is more like 10mm, so larger than a standard AC breaker.
Sorry Clive but that is not the contact on the bottom. When it is latched the contacts go forward into the 2 large copper plates and connect with the pips/contacts, below the arc block, either side and as they move forward they are forced apart and into contact by the relay pin in the centre in combination with the 2 springs in the plastic housing.
Clive, DC contactors also use magnetic arc chutes and it would be interesting to see inside one to compare. High spec used contactors like the ABB GAE75-10-11 are sometimes on Ebay for under 100 USD, and are rated for thousands of cycles per hour.
Yes magnets seem to be the main difference when I compared ac and dc breakers in a video a few years ago. You didn’t notice that dc breakers tend to be polarised. The tomzn ones most definitely are.
they have to be to work right....... unless you prefer the arc to be pushed back towards contacts ;)
How do you know which side is which?
@@mrtechie6810 there should be a diagram printed on the breaker showing the terminal with most potential. Usually marked with a +
Great stuff ,great video, a video about polarised DC breakers in general would be great as I think its the most under reported and confusing thing on UA-cam lots and lots about Double pole reversed polarity completely different than Single Pole though ,not seen any informative videos at all on SP Polarised DC breakers and how to wire them correctly ,I guess there must be thousands out there all wired wrong ,it really is bizarre how this can be especially with solar DC systems growing in popularity ,
Worse still that many solar systems are basically being installed by crash certified labourers.
How is the polarity marked?
@@mrtechie6810For single pole breakers there's is a diagram on the front but also they will usually have a + at one end and a - at the other end ,this is for single pole breakers ,for double pole breakers its slightly different .
well, an arc is a plasma, and plasma is affected by magnetic fields. makes sense to me.
It’s interesting to see in side them. I work as a cnc laser operator cutting all the copper parts and steel parts that go in side these to big sub stations. They have contracts with GE, MK, Facebook servers Williams F1 for the electrical side.
Love your channel always interesting
I was 7 minutes into this video when i realized you weren't looking out for purple springs...
"Purple Springs" is one of my favorite bands.... So is "Powerful Springs" featuring Hidden Magnet as the lead singer. That's more appropriate for this video.
250VDC @ 125A is ~32 kW. That's actually quite a small breaker for what its actually passing. Although AC breakers of that rating are usually polyphase, so they need to be wider since they connect multiple phases in the panel.
For dc contacts...250Vdc@125A..that tells you , at least for that much of a current flow that contact resistance must beat least (1/100to 1/500)( empirical) of (250V/125A)..
i.e. {(0.01) or(0.002)×2 ohms)..
There are various types and styles of Arc Quenching Device on switches and breakers and relays/contactors at all voltages and currents. I've seen the fin type on all the gadgets (isolation switches, circuit breakers, and contactors) up to the top of the LV regime, say, 500V. Above that the industry goes to MV (5kV or so) and that means vacuum bottle interrupting devices, which are intrinsically arc quenching.
i bet they tested it, bc its such an important safety device, i have learned to much about electronics watching your channel, awesome thatnks so much !!!⚡️⚡️⚡️⚡️
so the magnets WOULD have more use in the DC circuit as opposed to using a magnet with the AC,,right just due to the behavior of the DC? ( like in a TV the magnets move the beam in the picture tube and its DC (highvoltage DC))???
@@sa8die Yep.
I was expecting to see a ceramic or phenolic tab that would swing in between the contacts, and into a slot, to literally cut off the arc plasma. that would allow for high voltage, and would be indifferent to polarity. If the plunger in the solenoid is magnetized, that would also make it polarity specific. Using magnets to bend the arc into a quencher heat sink makes sense, and is probably more reliable than a gate, but that makes it polarity specific, as well.
Many is now making their own 12v, 24v and 48v DC systems with 100s of Amps using switches and breakers meant for AC at the AC rated limits without knowing they are creating a fire hazard ... When using a switch rated and approved for both AC and DC the DC rating is normally half the Ampere of the AC rating.
Nice design
Thanks for sharing
Because DC current is harder to interrupt, this unit would be a _Universal Circuit Breaker,_ if not for the permanent magnets set up for using Lorentz force on the arc (which also makes the breaker _polarity sensitive_ even though it's not marked as such). Previous to use of the magnets, any DC breaker would work to the same or higher current on AC. You can see this in the ratings on some switches.
Pity we cant get Mike with his Destruct-o-tron to test one of these :)
If I get my hands on a new 5G street light they are putting up in my area, with permission of course. Can I send it to you and break it down and tell us what these things are capable of and what they do?
They may have one or two that are defects but still worthy of exploring and I could possibly try to get my hands on one.
5G street light ?
You mean a light pole with a 5G (mobile network) antenna mounted on it ?
I don't think they're using 5G yet. The antenna is usually just an alternative to a time switch and dusk sensor for better control. The chance of getting a faulty one is slim as they are new and expensive so they tend to get shipped back to the supplier if they're faulty.
@@bigclivedotcom Might be AT&T's Project AirGig. From what I remember of the service when I used to work for them, it was going to integrate with 5G cellular signals and basically there would be dozens of cell site towers on top of power poles and light poles to provide better coverage than the centralized towers they've been using for decades.
@@Kinkajou1015 That would make sense as the 5G frequency range has less penetrating power, so is better suited to lots of small low power beacons.
@fuckin kazars Sabotaging fossil fuel usage is likely more effective. Not that I'd encourage it.
Please don't waste yourself on destroying telecommunications infrastructure. Please. Go all NIMBY on it if you _must_. But chemical pollutants are a far greater issue than whatever effects microwave radiation from cell towers has.
Schneider Activ-9 circuit breakers and the older C range are all rated for both AC and DC at rated current. Had to email Schneider tech dept to get the certification for them as they are used in an awful amount of industrial applications.
Usually only to 48 or 72V - I think Schneider is 48V only.
@@someonesomewhere1240 No, considering we were using 400v DC in some instances, I had to check with Schneider, they certified the breakers as being capable to take the rated current regardless of whether the load was AC or DC and the voltage rating was the same for both. If you brought an MCB or MCCB there was no down rating just because its DC. Consider that this was for large scale commercial Datacentres I was most insistant in getting that in writing as any downtime was measured in the millions of pounds per second. I had to be sure.
@@jeremytoms5163 That's interesting as that's contrary to their datasheets: download.schneider-electric.com/files?p_enDocType=Catalog&p_File_Name=CA908061E+(web).pdf&p_Doc_Ref=CA908061E
Perhaps you were using them for off-load switching (DC-20) only? There's generally noissue with carrying the load, only breaking it or interrupting a fault.
Someone Somewhere This is where it gets interesting, page 34 of the activ-9 catalogue. DC rating is 133vdc for 2&3 pole and 250vdc for 4 pole at 10kv , breaking capacity. As I said, I had to check as I'd read the same spec you had when I took over the DataCentres . I wondered how the install teams had got away with installing these breakers on Low voltage DC and so went to the technical team of Schneider for answers. I was lucky in that I'd dealt with them before on a few 11kv substation builds so already had contacts. The letter I had came from Schneider Technical in France. I emphasised that we were talking about DC not AC and they were quite unequivocal that their breakers would be rated the same both Volts and amps on DC and AC. Must admit that I was glad about that. Do you have any idea the hundreds of circuits we would have had to re-engineer across 7 DataCentres and 15 Nodes ? Can you imagine explaining to your customers that the previous installs were buggered and needed to be ripped out and by the way we're not sure if we can safely carry the load whilst we start rebuilding? That was a very anxious couple of weeks. One of the reasons that I hate DC in DataCentres, such a pain in the arse all round.
@@jeremytoms5163 I'd be most interested to read that email, given even load-break switches need to be massively over-rated for low-voltage DC.
You should send it to Mike to test it on his Destructotron
Thanks for the great pic of an ac waveform with 3 zero cross's. Just kidding. It was funny tho. That spring is so hard cause it gotta SLAP that contact open, EH? I luved your evaluation of the 3 leds lights -astro, less parts- Harbour Frieght, lot less parts--ebay light. Super Job!!
Great video Clive
Thanks for addressing this topic. Please clean your table after drilling. Watching the video with all that background noise makes my OCD explode. :)
So because of the magnet I assume these go only one way round, right? I mean, it'll still trip if the polarity is wrong but the magnets will push the arc away from the quencher instead of into it I think.
There are 2 magnets, in order to create sort of parallel magnetic field, so that the arc would deflect to the right or to the left.
@@nejiniisan1265, "deflect to the right or to the left"? Not at all. If that were the case, there would be no net magnetic field in the region, thus no force would be exerted on the arc at all. The second magnet is presumably there just to strengthen the field as well as cause the field lines to run parallel in the region between the two magnets.
@ManWithBeard1990 is correct; if the current runs in the opposite direction, the force exerted on the electrons due to the presence of the magnetic field would be in the opposite direction, directing them into the front of the device (where the switch is), rather than the back (where the quencher is). They would still move clockwise from the perspective seen in the video.
@@JivanPal oops
@@JivanPal ABB's version (S800S-UC) is rated for use in either direction, but they claim it has two arcing chambers per pole (both AC & DC versions), so I wonder if they have a different polarity in each chamber?
The lower-current version still has +/- markings.
Magnetic blowout is common on DC rated relays. The important rating to look at is the DC breaking current as its always lower than the switching current.
For dc ( unidirectional current flow) , a correctly polarized magnetic field is a must for rapid arc diversion & quenching.... therefore the direction of current flow ( wire polarization) is fixed and indicated on the breaker
The size of the gap between the contacts will be set by the rated voltage (as long as the arc is quenched on tripping) so as long as the voltage rating of the breakers are the same then the gaps will be similar
Erm, that's not my experience. At least with relays and contactors used in avionics. They are usually rated at the same current for both 28 VDC and 200 VAC (400 Hz). The voltage matters, but also whether it's DC or AC.
The reason they make these.. Is they can be mounted on Din Rails for Motor Controls and other devices. In a locked cabinet..And they have to be flash proof in industrial environments..A big deal if it's around a paint booth, fuel fumes, etc... And these vapors can get inside a cabinet. Why when I installed the wring in junction boxes. You had to seal the conduit at the entrance. They make special explosion proof seal offs just for this...
Hi Clive, I used to work for a company that I believe was the UK supplier/agent for Heinemann circuit breakers and if I remember right, these were much more complex inside. They were used notably within the marine, traction and aviation industries. Not sure how you could get hold of one of these, they were quite expensive. Craig.
As a Student in the mid 70's I worked a summer for Arrow Hart Switchgear. I was on the 3 ph contactor assembly line but did some overtime on their DC breaker line. I always remember the really big (as in half-inch diameter) cadmium plated contact pads I was resistance-welding onto the conductors going into the DC breakers.. These pads were rated for 200A max, so I'd be surprised if the contacts on BC's breaker were good for not much over 50A.
These breakers will be invaluable for protecting powerwalls and electric vehicles. Breaking the rated 37kVA load should make a loud pop, especially if powering an inverter.. I don't know what effect the magnets have but I can see why they included the mini "carrot slicer" spark gap array.
Minor nitpick: the current flowing through an AC circuit isn't likely to be zero at the zero voltage crossing. Any inductance or capacitance will knock the current out of phase with the voltage.
But at some point the current waveform will be zero regardless of power factor.
Hey Clive. Hope you're havin a good day!
It's impossible not to have a good day while taking apart something and discovering how it works.
I'd really like to see you take an MCCB apart Clive. Brand doesn't matter as they are all very similar in construction, We use them all the time but my boss just won't let me take one apart.
Surely, you will eventually have to replace a defective one. If it isn't too badly damaged, that might be a candidate for a deconstruction and inspection.
Getting DC breakers is harder than you'd hope. This, at 125a is amazing for being so tiny. We use 200a 2 pole breakers.... but thats a huge unit. Not a DIN mount. A good 2 fists of volume. 6 inch high, 2 inch across. Great chunking things. Biggest DIN mount, dc breaker ive met is a paltry 40a. Im no expert, but my technician spider sense would be very dubious of such a breaker. What's its breaking voltage? Under 48v, i might believe that rating.
My concern is, i didnt see a big arc supression feature. Maybe that is what the magnet is for. Ive seen big DC arcs drawn far longer than what spec sheets would lead you to believe. And an opening breaker is almost the same machine as one built to draw long dc arcs.
In my humble techie gutfeel, thats way to small...
The labeling claims 10 kA(!!!) breaking capacity at 250 Volts DC(!!!!). Even with that 2x2x2 cm arc extinction box, that seems like a very bold claim to me.
10 kA is quiet on the low side of breaking capacity for these breakers. The AC breakers here in Germany have a minimum rating of 10 kA for household installations. On industrial installations they require a braking capacity of 20 kA.
Edit: Had it wrong. See Gaunerchens comment below.
@@sebi7794 Yeah but that's for AC. Not DC. Totally different beast.
I'm with you, arjovenzia. That contact area is questionable, even for a 'one-use' purpose, and the separation when the contacts are open seems woefully inadequate. 125 A DC is into arc welding territory, and they're relying on a 'standard' sized contact, maybe 3-4 mm diameter, separated by about the same distance, to break that much current? At 250 V?!
It's that TOMZN chinese crap.. so probably lucky if it's actually break 24V never mind 240V DC
I guess the main difference is the tension on it to allow it to break the current, as evidenced by your sore finger
When this showed up in my subscriptions the title was truncated, ending with "unexpected arc".
Thank you sir.
Nothing new. When I first started electrical engineering; I was shown such devices over 55 years ago. They were installed on Slate control panels for elevators. They actually used the current flowing in the circuit to generate the magnetic field which helped quench the arc.
The blowout coil solution does seem more elegant than the permanent magnets, at least when you go up higher in current and voltage.
Interesting thanks for sharing that.
Clive on real size dc cb's 10kA load current rated ones they have blow out coils which you magnets replace, you have to remember the arc is a conductor with its own magnetic field, the object of those magnets is using the motor effect extend the arc up into the are chutes; extending the arc increases its resistance there by reducing the current and the arc chutes split the arc into the separate slots again extending the arc also cooling it.
DC cb's and contactors have an arcing contact, these are often sacrificial the main contact closes last and opens first.
The railways use DC CB's for circuit protection in third and fourth rail areas also trams systems
125 amps is bigger than my main house fuse and the electrons should be able to jump a big gap. JW showed an ac switch used in a dc circuit and it melted at the same same amperage
Tony Papantoniou Amps don’t matter in arcing, voltage does. So a 10 million amp source at .000001 volt won’t arc under standard temperatures and pressures but a 10 million volt source at .000001 A could arc several feet. Which is exactly why high voltage distribution towers look like they do to keep the transmission voltages as far away from ground and each other as necessary.
FYI minimum arc is 10kV in dry air, the reason you see household stuff arc in the sockets has to do with inductance and collapsing magnetic fields creating high voltage.
@@peterg.8245 DC needs bigger gaps on switches as it jumps further and quicker breaking
Do not know if i understand right, but if the pin is electric inline with the „coil“ and the arc being a sort of capacitive effect, i guess this can have a negative amplification effect. I have no real idea on analog electrics, just how i understand the explanation.
Are these still reliable after breaking such a current or should you just replace them because of the flash damage and pitting?
They generally have a rating as to number of full short circuit cycles they can endure, typically for these high current units that is around 10-20 cycles of breaking before they are considered worn out. That is why they also are backed up with a DC disconnector, so that you do not use up the longer lifetime at lower current ( it is roughly in inverse proportion to current, you might be specified as 1000 cycles at half current and so on) if you are often having to disconnect the load.
Huge difference between breaking nominal current and breaking at capacity. I don't know TBH how DC MCBs are rated, but for your usual AC MCBs they are rated to 20+k cycles at nominal current (which translates to several times In for some types). However, don't expect them to break 10 Kilo-Amperes a few thousand times. That won't happen. My guess would be that it is similar for these DC breakers, except that I assume they have much lower cycle ratings for nominal current. Switching DC is *hard*.
@@dasstackenblochen9250 If you look at the specs of a breaker, you will see an AVC rating(available fault current). This is the maximum amount that the breaker will successfully interrupt, without flash over. Usually, the rating is about 10,000 amps. Any higher, and you risk physically blowing the breaker to pieces, due to the temperature rise of the arc creating a plasma.
AC has a zero crossing, which occurs 120 times per second for 60 Hz, 100 for 50 Hz. DC does not offer a zero crossing, so you don't need much voltage, or current for the arc to continue flashing over. As the current switches polarity each half cycle. If you exceed the AFC, the arc may NOT extinguish during the brief zero crossing, and will maintain an arc, just like a stick welder. you've already described what happens next!
My 20A DC breakers kept tripping because my MPPT would occasionally decide to drop the voltage and the current would exceed the rating. So I've put the panels in series until I get around to upping the breaker. Now my MPPT gets quite hot. :(
Can you cook hot dogs on it?
@@dsloop3907 Pretty much. My fingers certainly feel cooked after touching it.
Actually Tomzn makes the best breakers at affordable price. They are so good that people have made fake copies of those without arc absorption and quality braided copper.
125 A through such a small contact area? That's difficult to believe.
Maybe it's 125 _chinese_ amperes, which means they added a '1' onto the front...?
SigEpBlue actually you may be right ,you know..passing that much current through that thing,doesn't end well.
At 125A the contacts weld together in a big blob of molten metal. They have no problem carrying 125A from then on :)
Please contact Wapredperception so we can see the arc plates working in slow-mo! That sort of thing would totally be his thing! Also reminds me of a teardown Photonicinduction did ages ago of a (several kiloamp? AC?) breaker that used some kind of copper brush for the contacts IIRC..
Clive, can you investigate the the polarisation of the two magnets? I'm wondering if putting multiple DC breakers side by side on the same DIN rail can cause issues because the magnets interact.
Very good point nut I doubt they would interact. They aren't powerful enough.
@@leonardjwright They seem to be neodymium, and they are on both sides, so only 4-5mm apart if two or more of these breakers installed on the same DIN rail next to each other..
Is that a new webstore, China Apparently?
If it's not, it should be.
You could test it with a DC arc welder.
Could you explain how to choose between the Class T fuse and the HRC fuse like NT00?
For the main fuse of a lithium battery, feeding an inverter.
I use two of these same mcb's beside each other (in parallel) for my 24 volt dc solar battery. The contacts get hot when i draw close to 80 amps, im afraid to go any higher. Thanks Clive
Interesting video! Question: you mentioned, "you expected more and.... it isn't going to perform as desired in a genuine fault situation like solar panels and stuff like that." But why not? or do I misinterpret and you mean it is, or might work as expected?
I'd be cautious about using this in a real scenario in critical applications. It might be fine for a low power remote application that didn't pose risk, but I regard stuff like this with no real local certification and testing as prototyping materials. It's better to use a properly certified unit in a real application to avoid liability.
Thanks for your answer! I agree. But if or if not it will be ok to use is still rather speculative without testing, which i know is outside the scope of this video. But maybe for a next video i would be very interested to see what’s the difference is between a din rail model from this video and a waterproof automatic resettable DC fuse/breakers for cars, audio systems, boats etc and are in the range of 30 to 300A also china made and from Ebay, Ali etc. Gr Luc
@@LucScheffers Cars are much lower voltage. Most reputable manufacturers' mains-voltage breakers are also rated for DC at up to 48, 72, or even 125V. Some have a *minimum* of 12VDC.
@@someonesomewhere1240 thanks for your input!
As to why it has two contacts, my guess is that one the contacts is basically a sacrificial contact that always draws the arc and gets pitted.
Somebody (can't remember who) did a video about an ancient submarine breaker. It had something like a sacrificial contact.
@@bdf2718 Photonicinduction did.
@@atonduke7612
I had a feeling it was him. And then I remembered the video was rather calm and controlled without flames and bangs, so decided it couldn't have been him.
This video makes me think of only one thing. I'm so glad that Nikola Tesla won the battle. Right ?
With DC we'd have been stuck with brush motors for a long time. Personally I'm not a fan of brush motors.
Brushless motors are ac motors with built-in dc to ac inverters. So without the idea of the ac motor, no brushless dc possible,,,
Many years ago I saw a d.c. circuit breaker from early in the 20th century rated at several thousand Amps. Frightening thing.
good content! Came here from electroboom
Do you know PhotonicInduction?
Any DC breakers, we used in industry used 2 pole, switching the negative as well as the positive. I have came across 3ph breakers wired in series. This breaker does not look as if it will last long, especially at the rated current.
Is there anything magnets can't make better?
Yes. Fuel consumption of cars. Even if charlatans claim otherwise. And let's not even begin on "health" magnets...
The distance needed is dependent on the voltage, not the current.
It's both. An arc welder only runs at about 20 to 30 volts, but at 150-200 amps to jump nearly 1/2 inch. You do have to touch the work piece to strike the arc, but it can be drawn out quite a bit, before it extinguishes, owing to huge current, even though the voltage isn't that high. inductive loads are the worst(large DC motors), because the inductance provides voltage, allowing the arc to establish.
@@vincentrobinette1507 You're right about the maximum distance the arc can go, I oversimplified.
The spacing of the contacts in the open position isn't determined by how long the arc can be when struck, only by how close the contacts need to be for the arc to start. The arc arrestor (block of plates with the magnet) size is what matters for extinguishing an existing arc.
I see you’re using one of those “mains testers”!!!
What would 125 Amp DC Circuit Breakers Be Mostly Used For? Most likely typical wide-spread usage would be Tow-Motor Battery Chargers as might not be large enough market for large solar or wind-turbine parallel wired arrays nearly as plentiful as thousands of warehouse two-motor chargers around. Even so, that design looks somewhat flimsy for reliable usage but again might be just fine.
Thanks Clive . I wonder if they do one in a clear plastic that would be interesting to see it break the circuit.
I'm thinking perhaps not though because of possibly clear plastic makeup but im not sure.
They do the AC breakers in clear plastic, but I'm not sure about the DC ones. You can't see the contacts in the clear breaker because they are in the arc containment area.
@@bigclivedotcom Ah yes that would be pointless then , shame you cant get them apart without parts pinging off the ceiling but they all seem to do that .
Thanks for the reply.
how many led Christmas strings will it run ??
So many that even Griswold will go "maybe that's enough".
Depends. Do you want to light up the leds or also the cables? ;)
@@adlerweb should i use 370vdc or 850vdc ???
Regardless of regulations, could you use that on AC and vice versa? And what potential problems may arise from doing so?
Those magnets are smart, but now I wander what would happen if it gets connected with the current flowing the wrong way. That would push the arc away from the extinguisher chamber.
Does not really matter, the magnets are there to force the arc into the quench chamber, they are likely multipole magnets so that the arc is just made longer, and eventually cooled down below ionisation temperature so it goes out.
@@SeanBZA This needs testing.
If it helps, think of the magnets at a right angle to the current flow, thus it doesn't matter the current direction.
125a yes BUT at what volts? its a major ask if the volts are in the 100 plus volts dc on load from solar panels . ps normally when u break a solar system the dc volts go up as the load go off making dis connection more problematic =not good
It literally has "DC 250V" written on it lol
Folks are down to taking apart strange things to see if they can find stuff that'll be fun to watch you make it explode.
Are those really called breaking plates? Because I immediately want to call them baffles. Oh well, I guess it's all semantics anyway, the important thing is they work.
The block for quenching the arc on some breakers is called an arc chute. This is a trade name such as in your web browser, is it bookmarks, favorites, or something else?
Hi, is this circuit breaker enough to protect Lifepo4 batteries or should it be combined with fuses?
Hi Clive have you seen one of these new powerbanks with 230v outlet? I saw one today from Polaroid. Only the size of a half liter beer can. Price was around 90€. If you had the chance to test one of these, that would be awesome! Greetings from Germany
DAMN that coil is THICC
Legend i fucking love your videos sorty for the profanity :)
How we can see if this thing is non-polarity?
I thought that the sole reason for not using ac switches for dc is the electroplating or electric machining effect that wears the contacts down.
AC current and voltage go through 0v/0a 100times a second, this breaks the arc much easier and usually limits how long the arc will last for. DC however doesn't do this, once the arc is started the superheated plasma conducts the electricity and reduces resistance and unlike AC it is always at full current and voltage.
i wonder if its easy to messure leakege current with a DC breaker circut...
These being safety (or "saftey", if you're Porsche...) devices, one would expect them to be tested before being shipped. You don't want to find out that you sold a dodgy breaker *after* the house fire...
is it for 250 volt? volt for DC is critical.
it had 250V on the label....
I could be wrong here ( it's never stopped me before ;0)) but have you not got it upside down? It would mean the arc being drawn Down .... now that is something I would like to see .... Eather way I am sure the regs say the distance needs to be greater for DC than AC.
Just out of interest what was the operating voltage?
@0.15 you can see it's rated for 250 v
@@ginvr Doh! ...... You must have better eyes than me! I turned it on to full screen and then only just made it out (well that is my excuse and I am sticking to it)
Interesting.
first i was thinking: don't open that hard spring loaded unit... but then i found out.. it was not loaded. wear gloves with spring loaded things...
I wonder, if you break a load multiple times in a quick succession, as in the case of some idiot trying to get the circuit running, will the arc suppressor fail to quench once it gets hot enough?
Hi. Total noob here. Watching to satisy my own curiosity with DC circuits. Could someone please clarify for me: the quencher dissipates the arc through the plates and air resistance, or is it more complex than that?
Also thanks Clive for your awesome videos!
Most small breakers rely on an arc characteristic that causes it to follow shaped rails that carry it into a stack of isolated metal plates that break the arc.
@@bigclivedotcom thanks Clive. For the arc to travel through the plates, is it still connected to the powered side, on one side of the plates (to direct the flow of electrons through the plates)?
What's the voltage rating of the breaker? Back when I was involved in that kind of thing, with avionics, relays and contactors were typically rated at the same current for 28 VDC as 200 VAC (@400 Hz). I know relays are not the same as breakers, but arcs is arcs and the same gap that will break a 200 VAC arc will break a 28 VDC arc of the same current. So, without magnetic arc suppression I'd expect a similar contact movement (give or take a few blonde ones) for 28 VDC as 240 VAC.
Magnetic arc suppression lets you handle more current and voltage in a similar-size package. So whether or not that breaker surprises me depends on the voltage rating.
Looking at the video the sticker seems to read 250V DC.
@@blahorgaslisk7763
Those magnets are a lot more effective than I thought.
The Nader NDB1-125 looks identical to this one. Label on breaker shows AC230/240. Spec sheet shows 60vdc.
Thank You much for all your vids , I am looking for a DC Braker that will actually trip at the specified 120A , Do you know a brand or model that will do that ? All the one's i can find and that i can see some youtuber's test alway's trip far over the specc , not good for protecting my ebike pwr pack and related parts , i wish this comment reach's your attention and that you have knowledge about my question , maybe a ANL fuse would work as long as it blow at its rated A's ( they also tend to go over ) Best Regards
All breakers have a trip curve based on a thermal response to a low overload and a magnetic response to a fast overload. A 120A breaker will trip with varying time above 120A but have a margin above that value where it will not trip.
Buying a prominent brand breaker in your country and observing the correct installation procedure is the best option.
@@bigclivedotcom Thank You so much for the @ sound of speed reply!! now my next thought is what if i get a 80A's dc breaker ? also i will set up on the + wire a anl fuse , the breaker used mainly as a switch ( wen i need to disconnect the "Y" paralell union) and a fuse as a over current cut off . Have you tested ANL ( or that kind of fuse ) if not i will gladly ship you some for you tp play with , i dont have gear to do test's of that type ,Cheers & Best Regards
@10:10, how many things can Clive hold with one hand?