Questions tagged [arc]
116 questions
25
votes
8 answers
Stopping electric arcs between layers in PCB - big PCB burn
Firstly, let me preface this with the fact that I am not interested in chastising the user, and I am not interested in looking at the original source of the arc (it was a tool accidentally breaching the power rails). This question is EXPLICITLY…
David Molony
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25
votes
4 answers
How can a high-voltage transistor be in such small packaging?
For example:
STN0214 - Very high voltage NPN power transistor
It is said to accept more than 1 kV between its collector and emitter. It comes in a SOT-223 package (3 pins plus a tab). With a dielectric strength of 1 kV/mm for humid air, cannot an…
julienfr112
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20
votes
3 answers
How can low voltage, high current (kA) power be dangerous?
Aluminum refineries use electricity to separate aluminum from minerals it naturally occurs in. This electricity typically takes the form of low voltage DC ("low" meaning 4 to 6 volts), at very high current (on the order of tens of kiloamps). This…
ItsAmy
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19
votes
3 answers
Why do fuses have a maximum breaking capacity?
Wikipedia told me that breaking capacity is the maximum current that can safely be interrupted by the fuse. I don’t understand why, if a small current can blow the fuse, a bigger current can’t. If the current which is bigger than breaking capacity…
Mei sy
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17
votes
3 answers
Light bulb burns out -- why there is an arc in the switch?
I use light bulbs (common incandescent) in the room and they
burn out periodically, ca. one bulb in 4 months burns out.
Very often, exactly at the moment when it happens, I see an arc (blueish light flash) in the switch, so the bulb always burns…
Mikhail V
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17
votes
9 answers
Is it really possible to "boost" 6 V DC to above 50 kV? Or even 400 kV?
I am trying to create an arc generator and I have read about the marx generator but I am looking into more compact modules like the image below. All the ones I have found seem to be fake and actually supply less than 1/10th of what they are…
stenlan
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16
votes
4 answers
Why does only the tip of the electrode melt when arc welding?
I saw on youtube some people performing arc welding with "consumable electrodes". At a first glance, I saw that the current flows through all the electrode and the workpiece and my question comes from this fact.
I think that the workpiece doesn't…
Tripola
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16
votes
3 answers
How far can mains voltage arc in air?
I wondered this while soldering a mains voltage circuit board and was surprised by how close together the traces were.
It has obvious implications in design of electrical plugs, and the proximity of wires when doing anything to do with mains…
M_M
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10
votes
4 answers
Why might a low-cost soldering iron die after short use?
It's been a while since I have soldered, so I bought a cheap unbranded soldering iron to use while I re-familiarised myself with the skill. After a few weeks of use, I turned it on just now and it popped with a blue spark. Now it appears to be dead.…
Nick Bolton
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8
votes
3 answers
The mosquito zapper from hell: why does it arc at different places instead of at the shortest gap?
A few years ago, I modified a mosquito zapper for fun, removing the original transformer and making the zapper more 'interesting'. I just found it again and I had an old question I wanted answered:
Here is the mod:
Here is a video of it in…
Thomas
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8
votes
3 answers
In the recent Con-Ed transformer "fire", what exactly produced the color of the huge blue glow over New York City?
Blue is often linked with technology (e.g. "big blue", glowing pools of water with Cherenkov radiation, aliens in general, Nobel prizes for blue LEDs) as well as traditional things like sparks.
In a huge transformer "fire" event like this, what…
uhoh
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8
votes
2 answers
Understanding cause of arcing in AC filter circuit
I have an induction hot-plate that one day blew a fuse in my distribution panel when plugging it in. (With the obligatory smoke from the device of course)
On visual inspection, only the AC filter PCB shows obvious damage:
simulate this circuit –…
ARF
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6
votes
5 answers
Why are arcs so hazardous compared to standard current flow?
I know that electric arcs are dangerous as they can start fires, cause explosions, melted insulation, etc. and they are generally undesirable.
However, I am a bit confused as to why. Arcs generate heat, but shouldn't normal current flow also…
Agniva Chaudhuri
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5
votes
2 answers
Ignition coil arc initiation with protected low voltage continuation?
I'd like to initiate a spark plug arc with an ignition coil and then power the resulting (highly conductive) plasma with an ultracapacitor (low voltage, say 12V to 24V, and high current) without damaging the ultracapacitor during the initiation. …
James Bowery
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5
votes
4 answers
Why does the cathode heat up more than the anode in an electric arc?
I have recently built a flyback transformer driver with a 555 timer, and have been drawing electric arcs. But I noticed that the cathode electrode(the HV pin on the transformer) heats up a lot more than the anode(the HV cable on top of the…
Bruno
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