DC Circuit Breaker Fires!!

Tecnodave · Dec 9, 2021

eXodus said:
View attachment 75101

I looked up those DC breakers,

My guess is that there is some sort of "Diode" mechanism inside, which doesn't like being run the other way around.

Don't know how they work mechanical but the symbols are different from AC:

View attachment 75102

Circuit breaker arc flash fires are caused by poor arc chute design or incorrect current flow in the breaker
Also by using an AC rated breaker on a DC circuit
Some (old standard) DC breakers are polarity sensitive, there is only one acceptable current flow direction
Current certification is non-polarity sensitive.

There is no diode in a circuit breaker, current flow direction has to do with the arc chute (arc extinguishing mechanism)

Old stock CBI (Circuit Breaker International) breakers are polarity sensitive

codes have changed

Current stock CBI breakers are not polarity sensitive

Carlingswitch breakers are not polarity sensetive......MidNite MNDC breakers are manufactured and labeled by Carlingswitch

Beware, many imported circuit breakers are polarity sensitive

AC breakers do not have an “arc chute” and have no way to extinguish an DC arc.

Very few breakers are rated for AC or DC

Carlingswitch “C” “D” and “E” series breakers are rated for both AC and DC

Schneider Electric Square D QO line breakers are rated 150 VAC and 48 VDC

740GLE · Dec 9, 2021

Tecnodave said:
Boeing Aircraft uses Carlingswitch.....

You mention this as a positive thing? Recent track record of Boeing isn’t helping your argument.

Texas-Mark · Dec 9, 2021

740GLE said:
You mention this as a positive thing? Recent track record of Boeing isn’t helping your argument.

What does a computer issue have to do with circuit breakers?

740GLE · Dec 9, 2021

I highly recommend you read “Flying Blind”

Boeing of the 80s and 90s is hardly the same company of today. Let me guess you’re a huge GM fan too?

Each manufacturer makes a product for a spec of the contract they signed. If the OEM request is to make a product cheaper the manufacturer will gladly oblige as they don’t want to lose the contract.

Tecnodave · Dec 9, 2021

740GLE said:
You mention this as a positive thing? Recent track record of Boeing isn’t helping your argument.

Please specify any Boeing aircraft that has had any circuit breaker failure causing a failure off that flight. Carrier, route, flight number, date......

I can absolutely guarantee you that has not happened

I am quoting an area where chinese circuit breakers are never used. As I have never been in an Airbus cockpit, but i would place a small bet that they are Schneider (German....not USA Schneider Square D)

Tecnodave · Dec 9, 2021

I write from expereince, by the time of the Alaska Earthquake I had my FCC ticket as well as a FAA special electrics and avionics as well as PIC of the J2, J3, PA18 Cessna 180, what is your experience there. I retired from one of the worlds largest electrical companies both in communications and power but Im here to share knowledge not get into a pissing match. Aircraft companies buy the best that is available, they do not specify a cheaper design.....which then needs certification by many agencies worldwide.......time is money.

Boeings downfall started with the McDonald Douglas company buying Boeing with Boeing’s money, They went from technical excellence to stock market baby.....

Many Douglas DC-3 aircraft are still flying, How many Boeing B787 and Airbus A350 plastic airplanes are grounded due to delaminating of the plastics and carbon fibrer

One of Boeing’s biggest mistakes was reengineering the B737 for engines that are not compatable with that airframe and scrapping the NMA design that was to replace it to compete with the Airbus A320 series

You can track Boeings downfall to moving to Chicago (moneygrubbers) andSouth Carolina (cheap labor)

robby · Dec 9, 2021

Honuz said:
Thanks for the video link, i was asking myself if this

Breaker was usable on the battery side, and found this thread while searching for the info. And while my question was not about PV breakers... your video answered my question... Those breakers seems to be rated for 24V max => No go.

Edit : Mmmm i can see they are 48V too...

Stay away from these. They Trip at the right Amperage maybe two or three times and then the internal mechanism starts to go bad. Also someone did a Flir image sensing on them and found one of the contacts gets very hot even during normal operation. He disassembled it and it was really poorly made.

Tecnodave · Dec 9, 2021

I have seen many of those, they light up my Fluke FLIR....I only use Buss brand in that style of breaker, Blue Seas are standard off the shelf Buss/Littlefuse. They just work.

740GLE · Dec 9, 2021

Tecnodave said:
Please specify any Boeing aircraft that has had any circuit breaker failure causing a failure off that flight. Carrier, route, flight number, date......

I can absolutely guarantee you that has not happened

I am quoting an area where chinese circuit breakers are never used. As I have never been in an Airbus cockpit, but i would place a small bet that they are Schneider (German....not USA Schneider Square D)

You made a generic statement that because a manufacture is used by Boeing, it must be good. Boeing has been far from the pinnacle of excellence for quite some time so your analogy doesn’t quite stand up. Follow the money. To me you pretty much said Yugo uses XXX band. . ..

I have no problem evaluating a company and the products they offer, but I won’t blindly give up my money because XXX OEM uses said products, be it Boeing, GE, GM, Samsung, Hitachi, Tesla or Apple.

Tecnodave · Dec 9, 2021

740GLE said:
You made a generic statement that because a manufacture is used by Boeing, it must be good. Boeing has been far from the pinnacle of excellence for quite some time so your analogy doesn’t quite stand up. Follow the money. To me you pretty much said Yugo uses XXX band. . ..

I have no problem evaluating a company and the products they offer, but I won’t blindly give up my money because XXX OEM uses said products, be it Boeing, GE, GM, Samsung, Hitachi, Tesla or Apple.

Personally I would much rather trust an well established American company verses any chinese manufacturing shop. But then I did a whole career doing high end electrics but.......I retired from GE....not really proud of their “dirty steam nuclear reactors” BWR’s if you know what I am speaking of.....

I think my point is any aircraft company will use Carlingswitch but not even consider a cheaply manufactured chinese breaker....lives are on the line

740GLE · Dec 9, 2021

Lives are on the line, so are dividends and quarterly earnings ? If things can be made cheaper and meet spec, it’ll be done and someone will get an attaboy.

I’ve never dabbled in the nuke world but did a stint of time for working for DoD on 688 fast attack fire control support (forward end). Everything was Hughes Enterprise, Signer, MacDonell Douglas, GE, Westinghouse designs of the late 60s, you could tell the companies cared about the +180 lives on the line. I saw the new stuff going in as “upgrades”selected by Raytheon, BAE and the like, it was a joke, yet met spec and was the lowest bidders.

There’s a reason deployment time has dramatically gone down on newly design boats.

Honuz · Dec 13, 2021

Did someone tried those

Fast fuse RGS7 700V/690V 30A 40A 60A 63A 70A 80A100A 125A 250A 260A 280A 300A 310A 350A 400A

15.12US $ 16% OFF|Fast fuse RGS7 700V/690V 30A 40A 60A 63A 70A 80A100A 125A 250A 260A 280A 300A 310A 350A 400A|Fuses| - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

a.aliexpress.com

Wait....

100LET | Eaton Bussmann series high speed British standard fuse | Specifications | Eaton

100LET - Eaton Bussmann series high speed British standard fuse, 100A, 200 kAIC, None, Fuse, Blade end X blade end, Stud - 100LET

www.eaton.com

10 watt power loss..! Is it at max amperage or all the time...!!

A.Justice · Dec 14, 2021

Honuz said:
Did someone tried those

Fast fuse RGS7 700V/690V 30A 40A 60A 63A 70A 80A100A 125A 250A 260A 280A 300A 310A 350A 400A

15.12US $ 16% OFF|Fast fuse RGS7 700V/690V 30A 40A 60A 63A 70A 80A100A 125A 250A 260A 280A 300A 310A 350A 400A|Fuses| - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

a.aliexpress.com

Wait....

100LET | Eaton Bussmann series high speed British standard fuse | Specifications | Eaton

100LET - Eaton Bussmann series high speed British standard fuse, 100A, 200 kAIC, None, Fuse, Blade end X blade end, Stud - 100LET

www.eaton.com

10 watt power loss..! Is it at max amperage or all the time...!!

Skip the AliX fuses.

I'm always hesitant to say this because there's actually a finite quantity, but I don't need fuses right now; Check eBay for used fuses, I don't think there's a single new fuse on my system, most of mine came out of forklifts. The last batch I got, IIRC, was three 75a units for like $4 each (they are around $30-50 each, new), and a 300a unit for $10 ($75-100, new).

Fuses, in particular, either work or they don't. It's not like they have any mechanical parts to wear out. Go with Bussmann, Fuseman, Ferraz-Shawmut, Blue Sea, Carlington, or Midnite. (Please don't jump on me, I'm sure I forgot a few good brands or two)

Impatient · Feb 16, 2022

I am revising my van setup. Without restarting the pizzing contest above, I could sure use some advice regarding a breaker / disconnect switch between the solar panel and the controller (“input” to the controller) BECAUSE I will be frequently switching the “output” from the controller between 2 different battery banks. I will soon have a higher voltage panel (250w, 51Voc, ~6a) and leaning toward a Victron Smart 100/20 solar charge Controller. I am not an EE (obviously), but am trying to use some common sense. I understand one part of the pizzing contest, and I side with higher-voltage-capable breaker. I want the convenience of a “switch” or breaker. ***My real question whether I need BOTH + & - wires interrupted by the breaker?*** Explorist Nate says yes (for code reasons???), whereas Will P seems OK with positive lead only…from what I have seen.

For convenience sake, I’ve toyed with using a 3PDT switch (or maybe it would need to be a 4PDT) so that it’s impossible to switch battery banks without interrupting the solar at the same time. In other words, 1 toggle would control both the “input” side as well as the “output” side of the controller. Such a “high” capacity switch is hard to come by in the 3P or 4P versions (26 week lead time). Today I have separate switches (1 for “in”, 1 for “out”), and often enough flip only the “output” switch, without worrying about the “input.” Morningstar support (for my current PWM controller) doesn’t condone this behavior, but nothing has smoked yet. They actually said the danger is to the downstream (“out”) loads getting fried, not the controller itself. I started worrying because the new panel is over twice (more like 2.5x) the voltage of the panel I spoke to Morningstar about, and there will be more amperage downstream of the controller than I have now, and I know nothing about the robustness of the proposed Victron.

RV10flyer · Feb 16, 2022

I have a few of those same Amazon circuit breakers. A 100A overheats and trips at 85A. It went in the trash. A second one is cool at 85A.

Cornwallav8r · Mar 26, 2022

Rbertalotto said:
I recently installed a new MPPT solar controller in my RV. While I was researching new SCC I stumbled upon a couple web sites talking about the proper way to switch solar panels on and off using a DC circuit breaker. So I ordered this one from AMAZON:

https://www.amazon.com/gp/product/B096315TSJ/ref=ppx_yo_dt_b_asin_title_o07_s01?ie=UTF8&th=1

DC Miniature Circuit Breaker, 2 Pole 1000V 63 Amp Isolator for Solar PV System, Thermal Magnetic Trip, DIN Rail Mount, Chtaixi DC Disconnect Switch C63"
I'm seeing where some DC circuit breakers have the leads switched on bottom and top....+ on the left on top and + on the right on bottom, and opposite for -.

This circuit breaker only calls out +/- on one end......There are no markings on the other end.

If you look at the attached link, there is some type of schematic on the front calling out 1,2,3,4....I'm not sure what this means.

I have it connected + to + and - to - running straight through the breaker..... Is this correct or am I going to burn my RV to the ground?

Three 140w / 12V panels in parallel.....with 4g wire of 25' to SCC

So to fix this....Connect source and loads negatives together if you can, so you don't have that dc voltage potential across those shitty China substandard breaker. Just switch positives. And throw those China breakers away. They suck.

Cornwallav8r · Mar 26, 2022

Kdkool said:
Probably why they failed catastrophically at those potential. The flipping of the terminals means that the traces are crossed internally and if the two traces are close enough to one another at the crossing, poof!

Breaker has no idea which direction current flows. Just trips when it's bimetal element sees sufficient heating, tripping the switch. Substandard China shit breakers though seem to know how to defy their ratings and fail miserably.

Cornwallav8r · Mar 26, 2022

RV10flyer said:
I have a few of those same Amazon circuit breakers. A 100A overheats and trips at 85A. It went in the trash. A second one is cool at 85A.

45a? I put in 4 150a breakers and they tripped below 30a. Lucky i didnt have a fire. I do forensics engineering, I am working a case in Maryland, a $20 rapid shutdown device serving 2 rooftop modules on a half million wtt system caught fire and burned half the million square foot roof off. Huge claim, with major subrogation lawsuits in different directions. I represent the building owner. 4 tenants insurance companies just now getting involved. The email list is like 4 lines long, probable 8 or more of us EEs on site next inspection. Really glad I am not Engineer of record on this one. Nothing to do with the failure, but the lawyers will sit after next inspection, after our lab analysis determines fault, and place proportional blame on all parties and proportion the liability payments. Big racket.

timselectric · Mar 26, 2022

Cornwallav8r said:
And throw those China breakers away. They suck

There's nothing wrong with this particular breaker.
If, wired correctly.
I have personally verified that it can extinguish a 450vdc arc.

Cornwallav8r said:
Breaker has no idea which direction current flows. Just trips when it's bimetal element sees sufficient heating, tripping the switch.

Polarized dc breakers require directional circuitry.

timselectric · Mar 26, 2022

There definitely are cheap Chinese breakers on the market. But, that's not one of them.

Cornwallav8r · Apr 6, 2022

timselectric said:
There's nothing wrong with this particular breaker.
If, wired correctly.
I have personally verified that it can extinguish a 450vdc arc.

Polarized dc breakers require directional circuitry.

This is DC, I stand corrected

Rbertalotto · Apr 6, 2022

Impatient said:
I am revising my van setup. Without restarting the pizzing contest above, I could sure use some advice regarding a breaker / disconnect switch between the solar panel and the controller (“input” to the controller) BECAUSE I will be frequently switching the “output” from the controller between 2 different battery banks. I will soon have a higher voltage panel (250w, 51Voc, ~6a) and leaning toward a Victron Smart 100/20 solar charge Controller. I am not an EE (obviously), but am trying to use some common sense. I understand one part of the pizzing contest, and I side with higher-voltage-capable breaker. I want the convenience of a “switch” or breaker. ***My real question whether I need BOTH + & - wires interrupted by the breaker?*** Explorist Nate says yes (for code reasons???), whereas Will P seems OK with positive lead only…from what I have seen.

For convenience sake, I’ve toyed with using a 3PDT switch (or maybe it would need to be a 4PDT) so that it’s impossible to switch battery banks without interrupting the solar at the same time. In other words, 1 toggle would control both the “input” side as well as the “output” side of the controller. Such a “high” capacity switch is hard to come by in the 3P or 4P versions (26 week lead time). Today I have separate switches (1 for “in”, 1 for “out”), and often enough flip only the “output” switch, without worrying about the “input.” Morningstar support (for my current PWM controller) doesn’t condone this behavior, but nothing has smoked yet. They actually said the danger is to the downstream (“out”) loads getting fried, not the controller itself. I started worrying because the new panel is over twice (more like 2.5x) the voltage of the panel I spoke to Morningstar about, and there will be more amperage downstream of the controller than I have now, and I know nothing about the robustness of the proposed Victron.

Just a caution.
Before you disconnect the battery from your charge controller, you need to disconnect the solar panels. Some, if not many, charge controllers will be damaged if the panels are connected without a battery connected. Good luck with your system.

Rbertalotto · Apr 6, 2022

Cornwallav8r said:
Breaker has no idea which direction current flows. Just trips when it's bimetal element sees sufficient heating, tripping the switch. Substandard China shit breakers though seem to know how to defy their ratings and fail miserably.

It's not about current flow with regard to direction. It is about arc extinguishing......

rmaddy · Apr 6, 2022

Rbertalotto said:
Before you disconnect the battery from your charge controller, you need to disconnect the solar panels.

Actually this isn't really true but it's a safe habit.

SCCs are not damaged if they lose battery power while still connected to PV.

Rbertalotto said:
Some, if not many, charge controllers will be damaged if the panels are connected without a battery connected

Most (if not nearly all) SCCs must be connected to a battery first the first time it is ever connected to anything. This is so the SCC can properly detect the system voltage. Some SCCs will remember that setting even if power is disconnected.

The most important thing is to connect battery power first then connect PV. It's probably a good habit to disconnect PV then disconnect battery power if needed. But if the battery is disconnected first and then PV, nothing bad will happen. Just make sure the PV is disconnected before reconnecting battery power. Though technically some SCCs won't care beyond the initial power up.

When in doubt, always try to ensure the PV is disconnected anytime the battery power is connected or disconnected.

Kornbread · Apr 6, 2022

Cornwallav8r said:
Breaker has no idea which direction current flows. Just trips when it's bimetal element sees sufficient heating, tripping the switch. Substandard China shit breakers though seem to know how to defy their ratings and fail miserably.

Wiring of a polarized breaker has come up often, so this may be useful to someone " ... Polarized DC circuit breakers use a small magnet to direct the arc away from the contacts and up into the arc de-ionization chamber. If the direction of current flow through the unit is reversed, then the magnet directs the arc away from the arc chute and into the mechanism of the unit, thus destroying it. ... ".

polarized dc circuit breaker

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