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I am gathering stuff for an upgrade to 24v Heated bed and I dismantled some stuff from an old PC style power supply. I want to use a PC style power socket for connecting to the mains with usual PC power cable.

[img]http://hennekens.info/rostock/PS_Connector.jpg[/img]

I saw these purple bulbs soldered between the fase and ground pins and it is probably a noob question but: what are they for and should I leave them?
Also I will integrate a switch and I am thinking about a fuse. Any recomendations about a fuse or a circuit breaker?

from what I understand, and don't quote me on this, those are y capacitors meant to filter out noise. You can eliminate them if you want, or choose not to. Personally, I would buy new IEC sockets if they are available to you easily (That is a more proper name for that part, an IEC standard AC receptacle), as that way you can be sure of the current rating, and potentially get a switch and fuse integrated as well. Whatever rating you have on that IEC socket and switch, I would pick a circuit breaker (Or fuse) that has a lower rating than that, by ~15%.

MOVs for surge protection.
https://en.wikipedia.org/wiki/Varistor# ... e_varistor

Xenocrates wrote:Personally, I would buy new IEC sockets if they are available to you easily (That is a more proper name for that part, an IEC standard AC receptacle), as that way you can be sure of the current rating, and potentially get a switch and fuse integrated as well. Whatever rating you have on that IEC socket and switch, I would pick a circuit breaker (Or fuse) that has a lower rating than that, by ~15%.

That is funny, the IEC has printed 15A as wel as 10A on it, both for 250VAC... But either would suffice wouldn't it? Going for an integrated IEC with fuse and switch is a good idea. I will look into that fur sure.

[img]http://hennekens.info/rostock/PS_Connector2.jpg[/img]

Andre B wrote:MOVs for surge protection.
https://en.wikipedia.org/wiki/Varistor# ... e_varistor

Great, thanks for the info! Would not hurt to leave them be then...

Xenocrates wrote:Personally, I would buy new IEC sockets if they are available to you easily (That is a more proper name for that part, an IEC standard AC receptacle), as that way you can be sure of the current rating, and potentially get a switch and fuse integrated as well. Whatever rating you have on that IEC socket and switch, I would pick a circuit breaker (Or fuse) that has a lower rating than that, by ~15%.

Great idea!
[img]http://hennekens.info/rostock/PS_Connector3.jpg[/img]
https://www.conrad.nl/nl/k-b-59jr101-1f ... 36709.html
Only 8 euro bucks.

DeltaCon wrote:

Xenocrates wrote:Personally, I would buy new IEC sockets if they are available to you easily (That is a more proper name for that part, an IEC standard AC receptacle), as that way you can be sure of the current rating, and potentially get a switch and fuse integrated as well. Whatever rating you have on that IEC socket and switch, I would pick a circuit breaker (Or fuse) that has a lower rating than that, by ~15%.

That is funny, the IEC has printed 15A as wel as 10A on it, both for 250VAC... But either would suffice wouldn't it? Going for an integrated IEC with fuse and switch is a good idea. I will look into that fur sure.

Those are ratings from different testing agencies so the same product can be sold in multiple countries. It's up to the manufacturer to use the correct certification/rating for his situation.
The IEC spec for that style of connector is 10A. It's the minimum standard that it's expected to meet. Certification is left to other agencies.
Actual testing agencies may assign higher ratings. In this case:
The UL rating is 15A. (the UL symbol for components is the backwards UR symbol).
The CSA rating is also 15A (symbol is a big C with SA inside it). It's a Canadian standards group.
Matching purpose IEC cords are still often rated at 10A, so I'd suggest using the 10A rating for safety purposes. People assume the cords are interchangable between devices.

Same deal with the switch. You've got two UL ratings and one CSA rating on it.

Those Blue lobes are either Film or Mica Capacitors similar to the linked one here on Mouser. They are used to make the power flow/wave form smoother (less noise).

There is a circuit called a 'Decoupling Circuit' that buffers the supply so if there is a voltage spike from say a small surge from the power plant the electronics after the 'Decoupling Circuit" will not see the spike. This is not a circuit that protects from large spikes like the ones you experience when your lights flicker from near lighting strikes. That is a whole another ball of a caps and resistors.

If you want to know more about them here is a Wiki link on the subject. I use them in audio circuits that are sensitive to the condition of the power that is being fed to them. But, this is not the only part of the conditioning of the power for an audio circuit. And again that is a whole nother ball of caps and resistors that is different from the surge suppress as well.

Personaly, I have a set of new caps and IEC connector waiting for my printer that is coming in on Monday. But, as many things in this world my opinion is not always the right one. So, do your research and decide if you want it or not and what the draw backs are if there are any for your 'design'.

That being said a IEC with a switch and fuse in one package is real good idea. I do like fire but only when i want it. So, i have push to reset thermal breaker to reduce the low chance my printer wires do not become heaters and turn my house into cinders.

Again this is my opinion and no i am not an EEE but do love playing with electricity in my projects. Your Mileage May Vary.

Pretty sure they're MOVs, rather than capacitors.

Seen plenty on lots of devices, they're there for surge protection.

Decoupling capacitors are a whole different kettle of fish, never that small, never right on the 240 V input, and never connected to earth.

nebbian wrote:Pretty sure they're MOVs, rather than capacitors.

Seen plenty on lots of devices, they're there for surge protection.

Decoupling capacitors are a whole different kettle of fish, never that small, never right on the 240 V input, and never connected to earth.

I went with Y-caps because it's a computer power supply AC input, and a person who tears down PSU's professionally (Jonnyguru) usually sees the Y caps on the AC in, and they looked to be about that size on the teardowns I saw. see here: http://www.jonnyguru.com/modules.php?na ... 5&reid=475, http://www.jonnyguru.com/modules.php?na ... 5&reid=471, http://www.jonnyguru.com/modules.php?na ... 5&reid=472. From what I saw, MOV's and other surge suppression in PSU's lives on the mainboard. Note that the color and size between the visible Y-caps and our mystery components is very similar. I wouldn't want a MOV attached to the IEC connector. Especially on it's own, due to the risk of thermal run-away making it harder to cut power by pulling the cord at that end. Instead, I would prefer it attached to the board where it can be parallelized, and sink heat to entire chassis, rather than just the AC receptacle and wiring.

Also https://www.tecategroup.com/capacitors/ ... citors.php shows that Y-capacitors are usually designed for line to ground connections.

DeltaCon,

Can you please take a closeup of one of those blue components that connect the line to the earth terminals? I'm particularly interested in being able to read the writing.

nebbian wrote:Can you please take a closeup of one of those blue components that connect the line to the earth terminals? I'm particularly interested in being able to read the writing.

Yes I can, have fun with it

Yep, capacitors, specifically an X1Y2 ceramic capacitor. I actually found a datasheet for it here: http://www.semiup.com/pdf/SEC02.pdf

100 pF 10% 250V capacitor

That datasheet also identifies many certification marks I didn't mention, if you're interested.
The testing procedures on the last 4 pages are interesting, as well. 30 seconds in a gas flame, for instance.

And to whoever said it above, these would be classed as line filter caps, not decoupling caps.

Gosh, well you learn something new every day.

I didn't think you could use caps like that, I thought they were always MOVs, designed to pull so much current in the event of a surge, that it trips the overcurrent circuit breaker.
With caps arranged as they are, I would have thought that if you turned it on at the wrong part of the cycle, it might pull enough current to trip the earth leakage breaker.

Carry on, carry on, nothing to see here.