Artificial hand test for EMC testing? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: April 21, 2023, 06:11:01 am
content: Hi,Has anyone heard of the "artifical hand test" for offline conducted EMC testing?Does it apply to all plastic enclosed offline SMPS with no earth?What if there is an earth connection?...but it goes nowehere and does nothing?...

author: pdenisowski
author_rank: Super Contributor
timestamp: April 21, 2023, 12:10:42 pm
content: EN 55011 requires the use of the artificial hand when testing hand-held equipment"In order to simulate the influence of the user's hand, application of the artificial hand is required for hand held equipment during the disturbance voltage measurement. The artificial hand consists of metal foil which is connected to one terminal (terminal M) of an RC element consisting of a capacitor of 220 pF ± 20 % in series with a resistor of 510 Ω ± 10 % (see Figure 8a); the other terminal of the RC element shall be connected to the reference ground of the measuring system (see CISPR 16-1-2). The RC element of the artificial hand may be incorporated in the housing of the artificial mains network."That said, I wouldn't consider a SMPS in a plastic enclosure a "hand-held" device, so my feeling is that this requirement doesn't apply in this case.

author: Gyro
author_rank: Super Contributor
timestamp: April 21, 2023, 12:57:37 pm
content: I don't think I would want to risk holdinganythingthat Faringdon had designed in my hand while powered!

author: pdenisowski
author_rank: Super Contributor
timestamp: April 21, 2023, 02:09:43 pm
content: Quote from: Gyro on April 21, 2023, 12:57:37 pmThat could describe a lot of my designs tooArtificial hand is usually needed for things like power tools (a drill is the common example, since this is the example given in one of the specification), but it can also be used for keyboards, touch screens, etc. In many cases, the artificial hand is connected to a LISN via a dedicated connector.

author: Faringdon
author_rank: Super Contributor
timestamp: April 21, 2023, 08:01:44 pm
content: Thanks, i am not sure to what products the artificial hand test applies?....is it only plastic contained offline smps with no earth connection?

author: pdenisowski
author_rank: Super Contributor
timestamp: April 21, 2023, 08:45:21 pm
content: Quote from: Faringdon on April 21, 2023, 08:01:44 pmMy guess would be no.

author: Faringdon
author_rank: Super Contributor
timestamp: April 22, 2023, 10:52:07 am
content: Thanks, but i think its too stop power supplies with no earth, cheating their way through conducted emissions testing.(no earth, no common mode emissions)..so in other words, it is only for offline SMPS's with no earth. The earth is brought in by way of the "artifical hand".

author: jonpaul
author_rank: Super Contributor
timestamp: April 22, 2023, 02:40:28 pm
content: FTTS, wrong again, usual nonsense.Suggest you take a long vacation away from any electronics....Have a great day!j

author: Faringdon
author_rank: Super Contributor
timestamp: April 23, 2023, 09:32:26 am
content: Thanks, ayk, there wouldnt be any point in bringing an earthed "artifical hand" to the SMPS if it already had earth inside it.pdenisowski in post #1 above kindly delivers the info.It is a metal foil, but does that metal foil get wrapped right round the power supply.?PSU (eg laptop PSU) is not "handheld device", but it couLD be held in the hand, so it needs the metal foil to be wrapping it during conducted EMC.What about eg drills which have an offline psu in them, but often have holes for vents in the casing....the wrapping of the metal foil will obscure the vent holes....and cause the electronics to overheat?

author: pdenisowski
author_rank: Super Contributor
timestamp: April 23, 2023, 02:58:51 pm
content: Quote from: Faringdon on April 23, 2023, 09:32:26 amEssentially, yes, the foil should cover the area(s) that would normally be covered by a human hand.Quote from: Faringdon on April 23, 2023, 09:32:26 amWell, if it overheats when it has a piece of foil on it, it's probably going to also overheat when it's covered by a human hand

author: pdenisowski
author_rank: Super Contributor
timestamp: June 14, 2023, 09:16:53 am
content: I realized that there wasn’t much introductory information about artificial hands so I decided to make a short video on the topic

author: tggzzz
author_rank: Super Contributor
timestamp: June 14, 2023, 09:34:21 am
content: Quote from: Gyro on April 21, 2023, 12:57:37 pmPlus I don't think I would want to risk havinganythingthat Faringdon had designed in my house while powered!