Y2 capacitor thickness and width ambiguity - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: November 16, 2023, 12:54:53 pm
content: Hi,The WYO2222MCMBF0KR 2n2 Y2 cap has a "thickness" of 4.5mm, and a "width" of 1.4mm...but the drawing on page 2 of datasheet shows these 2 dims are the same one....do you know what is wrong?WYO222MCMBF0KRhttps://www.vishay.com/docs/22202/wyo.pdf

author: wraper
author_rank: Unknown
timestamp: November 16, 2023, 12:58:13 pm
content: Rinse your eyes and look on the drawing again.

author: tggzzz
author_rank: Super Contributor
timestamp: November 16, 2023, 01:57:29 pm
content: Quote from: Faringdon on November 16, 2023, 12:54:53 pmYes we do. As shown in the image below, the datasheet is sane and easily understood.To reduce the chances of you embarrassing yourself again in the future, can I suggestyou follow wraper's suggestion, andbeforeposting youwaitthenthinkandonly finally post.

author: Zero999
author_rank: Super Contributor
timestamp: November 16, 2023, 02:15:22 pm
content: Why start another flaming thread?I already told you. If the capacitor bridges the rectified mains and secondary side, then it must be a Y1 capacitor.A Y1 capacitor has a higher peak voltage rating and a large lead spacing (longer creepage/tracking distance) than a Y2 capacitor. A Y2 capacitor is not good enough, unless two are connected in series but you said there's only room for one.

author: wraper
author_rank: Unknown
timestamp: November 16, 2023, 02:42:36 pm
content: Quote from: Zero999 on November 16, 2023, 02:15:22 pmI dunno what thread this is about but without a context it makes not sense. You need Y1 or two Y2 in series only if it's double/reinforced insulated device. If it's earthed, a single Y2 is perfectly suitable.

author: wraper
author_rank: Unknown
timestamp: November 16, 2023, 02:45:51 pm
content: Quote from: tggzzz on November 16, 2023, 01:57:29 pmIs it even possible to achieve it to higher level than already is?

author: tggzzz
author_rank: Super Contributor
timestamp: November 16, 2023, 03:33:49 pm
content: Quote from: wraper on November 16, 2023, 02:45:51 pmGiven that several people responding to several of the OP's threads have recently had several of their posts deleted by a mod, I think it pays to be polite and helpful.

author: HwAoRrDk
author_rank: Super Contributor
timestamp: November 16, 2023, 04:37:02 pm
content: The diagram is pretty clear. The Width is for the main cylindrical body, and the Thickness is the total thickness of the entire part including the legs.If OP is confused as to why there is such a great difference between the two (1.4 vs 4.5 mm), note that the Thickness is amaximum. That is, parts may beup to4.5 mm thick, and that is the minimum space you should allow for on the board. Probably 90% of parts are not that thick, but due to the variability of the epoxy dipping process, some might have excessive amounts covering the legs.

author: Zero999
author_rank: Super Contributor
timestamp: November 16, 2023, 05:19:44 pm
content: Quote from: wraper on November 16, 2023, 02:42:36 pmThe DC power supply may be earthed, but it still requires a Y2 capacitor/two Y1 capacitors connected between the mains and secondary side.

author: wraper
author_rank: Unknown
timestamp: November 16, 2023, 05:24:01 pm
content: Quote from: Zero999 on November 16, 2023, 05:19:44 pmYou mixed up Y1 and Y2. And nope, you don't need two Y2 caps is series for earthed devices and mass produced (certified) devices are a good example of this.

author: Zero999
author_rank: Super Contributor
timestamp: November 16, 2023, 06:45:40 pm
content: Quote from: wraper on November 16, 2023, 05:24:01 pmIt has nothing to do with whether the appliance is earthed or not, but whether what the capacitor is connected to is earthed or not, not the appliance. A DC PSU, with metal and earthed case and a floating secondary, will need a Y1 capacitor connected between its secondary side and the mains.

author: wraper
author_rank: Unknown
timestamp: November 16, 2023, 06:57:54 pm
content: Quote from: Zero999 on November 16, 2023, 06:45:40 pmNow you say about capacitor connected to thefloating secondary(that implies reinforced insulation) when I said in the first post that it makes no sense without a context. EDIT: Also if PE is present, why would you connect the Y cap from the live circuit to the output and not from live to PE and from PE to the output?

author: Zero999
author_rank: Super Contributor
timestamp: November 16, 2023, 07:03:31 pm
content: Quote from: wraper on November 16, 2023, 06:57:54 pmIt can have reinforced insulation to the secondary, even if the metal case has basic insulation. It's a Treez thread, hence the lack of context. We both should have known better.

author: tggzzz
author_rank: Super Contributor
timestamp: November 16, 2023, 07:36:36 pm
content: Quote from: Zero999 on November 16, 2023, 07:03:31 pmYes.But don't worry, a little context will dribble out over the next 24 hours.Not enough context, because faringdon is worried we could steal his knowledge (as per previous posts and responses, now deleted by a mod).

author: Zero999
author_rank: Super Contributor
timestamp: November 16, 2023, 08:27:26 pm
content: Quote from: wraper on November 16, 2023, 06:57:54 pmGood point, but I've seen it before. I assume it was because they used an SMPS module, which didn't have a PE.