Arc detection- suggestions - Page 1
Forum section: electronics / rf-microwave

author: IconicPCB
author_rank: Super Contributor
timestamp: August 21, 2018, 07:07:42 am
content: I need to monitor a switch board and raise an alarm should arcing take place for what ever reason.I would like to hear of Your experience with various detection schemes ranging from simple HF filter/envelope detector to more sophisticated solutions.

author: tautech
author_rank: Super Contributor
timestamp: August 21, 2018, 09:06:54 am
content: Would just a simple LDR based circuit do ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 21, 2018, 09:21:03 am
content: Does it need to not detect when a switch opens or closes in a normal fashion?Tim

author: PartialDischarge
author_rank: Super Contributor
timestamp: August 21, 2018, 09:32:53 am
content: Arcing is usually detected electronically via current/voltage sensing for "low" energies.For medium voltage (>1kv <36kV) and low impedance lines optical sensing is used. Here energy is so high that electronics can't be relied upon, so normally a naked fiber optic is passed through the system and the coupled flash is sensed.

author: IconicPCB
author_rank: Super Contributor
timestamp: August 21, 2018, 11:09:15 am
content: Tau,Do you mean visual detection of arcing?Tim,A gated or time duration weighted discriminator of some kind would be necessary to ignore contact closureMaster Tech,I think something less specific than a fiber optic approach would probably fit the bill.I had wonderd whether ultra sonics could be used to listen for the characteristic hiss( or may be snap crackle and pop ) usually associated with serial break down.

author: Berni
author_rank: Super Contributor
timestamp: August 21, 2018, 11:21:54 am
content: The sound that the arc makes can be very different depending on what is arcing. When its mains voltage the arc can make a very angry sounding 100 or 120Hz buzz. If its perfectly smooth DC then the arc just makes a pop when it starts and once it goes out. If the hot air causes significant wind and turbulence around it then it can sound similar to a cloth flapping in the wind. If the arc heats up the contacts to make them start boiling off that can create crackling noises. If the arc is supplying current to a giant audio amplifier then the arc will make the same sound as the amplifier is outputting.Radio interference can also be used to sense an arc but can be hard to predict in the metal cabinets that large switch gear is usually housed. But light is pretty much always made by arcs. It produces everything from IR to visible to UV, if you want some resilience from ambient light then you might look only at the really high energy UV since that sort of UV is blocked by the atmosphere so it shouldn't be too sensitive to sunlight and most man made light sources don't produce it because its harmful to people.

author: rhb
author_rank: Super Contributor
timestamp: August 21, 2018, 03:19:05 pm
content: They now require arc fault interrupting breakers in some places. You might want to look into how those work.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: August 21, 2018, 03:28:05 pm
content: https://ieeexplore.ieee.org/document/5487029/I"m sure you can find more papers on this topic here. If you can't get behind the pay wall go to a university library and you probably can access IEEE for free.Andy

author: nfmax
author_rank: Super Contributor
timestamp: August 21, 2018, 04:14:23 pm
content: The QUAD ESL63 electrostatic loudspeaker had a simple arc detector as part of its protection circuit:http://www.meridian-audio.info/public/esl63%5B1641%5D.pdfThe aerial was a short length of wire between and and the bottom of the two fixed electrodes. Arcing could occur between the two electrodes if the speaker was overloaded, especially in a damp atmosphere at high altitudes. An arc blasted a small hole in the moving diaphragm. It was surprising how little difference this made to the sound - in moderation