IEC61000-4-4 event in real life - Page 1
Forum section: electronics / projects

author: prasimix
author_rank: Unknown
timestamp: January 21, 2021, 09:12:10 am
content: I'd like to learn about real life cases thatIEC61000-4-4test wants to simulate. It says:The cause of electrical fast transients (EFT) come from an arc when mechanical contact is open due to a switching process. Given the fast rise time and voltage of these pulses having a solid ground connection is important during the testing process.How one can experience such event in home environment (e.g. in one's basement hobby workshop, etc.) and how often? Thanks.

author: jonpaul
author_rank: Super Contributor
timestamp: January 21, 2021, 02:56:20 pm
content: Apply 20 A load eg heater on 15 A breaker.Wait till breaker trips out.Arc is inside breakerOR use any large switch on a 10 - 30 A inductive load eg 1 hp motor.Jon

author: poorchava
author_rank: Super Contributor
timestamp: January 21, 2021, 03:02:23 pm
content: We even had a DIY device at work, that consisted of 2 mains rated relays driving one another to form an oscillator. The EM noose that this produces was extreme.

author: prasimix
author_rank: Unknown
timestamp: January 21, 2021, 03:45:50 pm
content: Ok, does DIY solution also include some coupling of that "noise" to AC line, or that relays need to be connected somehow with E.U.T.?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 21, 2021, 04:10:37 pm
content: Well, you're not going to have "good grounding" in a home environment (read: commercial equipment in typical use). That's required to standardize testing, for which without, results would be very inconsistent.The connection would be same as any other situation. Either the auxiliary load is wired in parallel with your EUT mains connection, or routed in parallel so that coupling occurs inside the conduit carrying both connections. (This phenomenon is tested specifically using a capacitive clamp.)The generator is also specific and well-controlled, so that results are meaningful, consistent, and can be varied to investigate sensitivity. A mechanical oscillator in a random environment will have none of these features, and won't even be easy to measure (how would you connect a 50 ohm attenuator and scope?).Tim

author: jonpaul
author_rank: Super Contributor
timestamp: January 21, 2021, 04:37:44 pm
content: There is an arc, which excites a resonant tak: Wiring is the L, stray cpapcity the C.The result is a damped exponential ringing, for each arc initiated.Early radio TX used spark gaps this way.The interference is BOTH conducted via the wires to the mains, AND radiated as the wires act as antennas.So we have a RADIATED and CONDUCTED EMI situation that needs BOTH line filters (CM and DM noise) AND shielding to reduce the noise or comply.Suggest to study the many fine books on EMI and compliance as well as transient generation and protection, huge topics.Bon chance,Jon

author: prasimix
author_rank: Unknown
timestamp: January 21, 2021, 05:32:06 pm
content: Quote from: jonpaul on January 21, 2021, 02:56:20 pmOut of curiosity, how long could such an event last, since test procedure lasts 4 minutes, i.e. 240 seconds in a row.

author: jonpaul
author_rank: Super Contributor
timestamp: January 21, 2021, 07:09:13 pm
content: An arc can be any legnth of time!EG milliseconds eg house 20 A 240V breaker trip or minutes eg HV substation 240 KV 100A air breaker faultOld carbon arc lamps could burn carbon electrodes for hoursTesla Coil rotationg spark gaps have 100 uS..1 mS depending on speed.Check the IEEE notes on this standard, and compliance test gear manufacturers.https://en.wikipedia.org/wiki/IEC_61000-4-4References"IEC TR 61000-4-1:2016 - IEC Webstore - electromagnetic compatibility, EMC, smart city". webstore.iec.ch."IEC 61000-4-4:2012 - IEC Webstore - electromagnetic compatibility, EMC, smart city, rural electrification". webstore.iec.ch."IEC 61000-4-4 Fast Transient/Burst Testing Lab with EMC / EMI Experts". Keystone Compliance.IEC 61000-4-2 (3.0 ed.). International Electrotechnical Commission (IEC). December 2008. p. 11. ISBN 978-0-58069-361-8."Teseq: IEC/EN 61000-4-4".www.teseq.com."EN IEC 61000-4-4 - EFT/Burst Immunity Generator Rentals". Transient Specialists."Modeling the IEC 61000-4-4 EFT injection clamp - Request PDF". ResearchGate.Jon

author: jbb
author_rank: Super Contributor
timestamp: January 22, 2021, 06:03:08 am
content: Quote from: jonpaul on January 21, 2021, 07:09:13 pmStory from the lab:“Hmm, this DC circuit breaker has aminimumbreaking current rating. And PV (solar) panels are current limited...”“Let’s hook it up to the PV emulator and see.”A few minutes later.“Oh, yes, that’s arcing.”...“It’s not going out, is it?”...“We’re going to need a new circuit breaker.”

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 22, 2021, 03:50:18 pm
content: Neat, magnetic breaking I guess?Tim