safety and protection devices and method tutorial - Page 1
Forum section: electronics / general

author: SnakeBite
author_rank: Regular Contributor
timestamp: July 31, 2011, 10:20:07 am
content: Hello Dave and other readers,i have a great idea for future Vblog- biog about safety spec (UL and other safety standarts) and safety devices.i thought to divide this Vblog into two sections:1. user safety - devices and spec that protect the user and the user's equipment that connected to the product you made - Electric shock , overcurrent ....2. hardware protection - devices and spec that protect your product internal hardware like - fuse , polyswitch , ptc , movs , ESD protection, zener diode protection , shunts etc..., short circuit protection,over-current , over-voltage , reverse current when coil discharging , protect sensitive devices like transistor from damaged components like electrolytic capacitorsthe hardware part also can divided to two sections : introduce the safety devices out there and giving a practical example where is a common place to use them...i know it's can be A LOT of work to make this kind of video but I'm sure everyone in youtube and in the forum would like to see this tutorial and it's important to almost every electronics project.thanks for all you effort, keep it upIdo , Israel

author: Neilm
author_rank: Super Contributor
timestamp: July 31, 2011, 06:58:22 pm
content: As someone who has worked in qualifying instruments (IEC61010) I have seen the consiquences of circuit designers and PCB designers not knowing about this. I have seen instruments fail under test - Imagine an instrument exploding and taking out a 100A fuse under short circuit conditions. (multi-meter accidently set on amps connected to a 600V supply). It is this sort of situation that a good and responsible designer will use fuses, MOVs and the like for user safety.In the case sited above, the manufacturere explained that as the case should have contained the explosion, the user was still safe (this was to the old version of 61010). Would anyone here be happy if the instrument you were holding exploded in your hand - even if the explosion was contained?YoursNeil

author: saturation
author_rank: Super Contributor
timestamp: July 31, 2011, 10:00:06 pm
content: Safety first, very difficult to repair a hand, very easy to buy a new DMM.

author: SnakeBite
author_rank: Regular Contributor
timestamp: July 31, 2011, 10:54:50 pm
content: Quote from: saturation on July 31, 2011, 10:00:06 pm*thumb up*so if i understand you correctly , you agree with me that it's important to make a tutorial on this matter...right?!

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 31, 2011, 11:18:57 pm
content: All regulations over safety there is out there in a document format.All that you need to do is to just read them.It is understandable, that me as electrician I have not to worry that much for all those step down AC/DC PSU that replaces the common transformers in almost any modern electronic device.But if you truly need to become informed about those, you need something more than a 20 min Vblog.

author: Rufus
author_rank: Super Contributor
timestamp: July 31, 2011, 11:44:49 pm
content: Quote from: SnakeBite on July 31, 2011, 10:54:50 pmI think a tutorial advising people on how and why not to stick short circuits across high voltage 100A capable supplies would be more useful. Being saved by an expensive fuse it a multimeter ain't a solution.Years ago on a late shift an electrician was called in to fix a breakdown. We were sitting downstairs in the workshop and heard a loud thud. A few minutes later a white faced electrician walked through the door clutching a 10 inch screw driver with 8 inches of it missing. The thud we heard was a supply fuse blowing. Where are you going to fuse a screw driver?

author: saturation
author_rank: Super Contributor
timestamp: August 01, 2011, 12:14:39 am
content: Yes, absolutely. There is a lot of material say by Fluke or government organizations like OSHA, but there is always room to make it clearer, better, and up to date.In our organization, we have safety training annually for the risks we are exposed too.Quote from: SnakeBite on July 31, 2011, 10:54:50 pm

author: vk6zgo
author_rank: Super Contributor
timestamp: August 01, 2011, 06:00:14 am
content: Quote from: Rufus on July 31, 2011, 11:44:49 pmThis brings to mind the occasion at a TV Transmitter,where the time switch for the mast lights failed.The Electricians came up,had a look,& decided to replace it with a modern,smaller equivalent.After measuring the distance between mounting points,they went away & mounted the new one on a piece of steel strip,which unfortunately,they left a bit long.When the time came to fit it,they assured us that all we needed to do was to put the station on emergency power(a big Dorman Diesel),so they could turn off the mains & wire the thing in.We made the switchover,& they set to work,one bloke supervising,& the other working inside the Power cabinet.Suddenly there was a blinding flash,& the Diesel stopped instantly!We rushed to the Electrician's aid,expecting to see a pile of ash,but he was all right,just a bit freaked out.We put the station back on the mains,fired everything back up,& took the"Sparky" for a cup of tea.It seems that he shorted out two phases of the emergency supply,whilst trying to manoeuvre the steel strip into position.We expected the Diesel to have suffered from the sudden stop,but it was a tough old Brit,& soldiered on for another 10 or so years.Not sure of the long term effect on the Electrician though!VK6ZGO

author: ejeffrey
author_rank: Super Contributor
timestamp: August 01, 2011, 07:42:04 am
content: Quote from: Neilm on July 31, 2011, 06:58:22 pmI guess it depends on what you mean by 'exploded but contained'. I assume you mean the meter was destroyed but didn't present a hazard to the user? I would rather the meter survived intact and only required a fuse replacement, but honestly I don't care that much. A $400 lesson about not doing stupid things plus an uninjured hand sounds like a pretty good deal to me.Anyway, I think this is a fantastic idea. Even circuits not designed or rated for use in high power situations often need at least protection diodes to protect against ESD and SCR latchup when connected.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: August 01, 2011, 10:58:59 am
content: Quote from: vk6zgo on August 01, 2011, 06:00:14 amI have plenty memorable stories LOL , and even with out a human error involved.Those tiny mouse they love the heat in the cabinets where the fat bars and distribution switches coexist.When they try to walk under the fat bars, and touch two phases with their legs,they become nice fireworks, the workers get scared from the sound or the smell.And eventually the electrician Sparky is on his way, to remove the cause of the accident.

author: SnakeBite
author_rank: Regular Contributor
timestamp: August 01, 2011, 04:09:16 pm
content: please guys , don't go off topic.i know all have stories but let stay on topic which is :"if you think is a good idea that Dave will make a vblog on safety devices?"Ido

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: August 01, 2011, 11:03:41 pm
content: SnakeBiteYou are new in this community, and probably not familiar about how Dave Jones think.There is no any public voting that will force Dave to select an subject.The other way it works, Dave comes and asks one question about an possible subject of one Vblog,and he gets our feedback.If you need a personal direct answer from him, just send one email to him.

author: SnakeBite
author_rank: Regular Contributor
timestamp: August 02, 2011, 07:59:55 am
content: Kiriakos-GRI'm not that new (more than a year) and nobody say anything about forcing anyone.i think if dave see that the idea has a lot of supporters he will tend to do a vblog about it even though i know that it's a lot of work to make such a blog.Ido

author: ciccio
author_rank: Frequent Contributor
timestamp: August 03, 2011, 11:35:48 am
content: I think this is a good idea, the only problem is that the rules and regulations are many, and a lot complicated, and change from country to country, and even from one certifying body to another.One of my colleagues summed things up this way:in "low voltage countries" (e.g. USA, Canada, Japan, etc) the risk is fire but houses are built of wood, why did they opt for low voltage?in "high voltage countries" (e.g. Europe, etc) the risk is electrocution, houses are mostly made of bricks, lower danger from fire...I believe that some simple indication from an expert about mains wiring, creepage distances on PCB, dual insulation, etc, could be appreciated by the "beginners" and a great "rehershal" for the "old experts"

author: eddy66t6
author_rank: Contributor
timestamp: August 07, 2011, 08:33:50 pm
content: Really Agree! A tutorial on picking a PTC in particular for over current protection would be brilliant, any info i get is just too deepend stuff and usually flies overhead!An explanation video Dave style would really help!!