Hello,
You can find a million internet reports on X2 capacitors…eg...
https://ac-dc.power.com/system/files...-docs/an15.pdf
..but none of them state if it’s an actual regulatory requirement for a capacitor from line to neutral upstream of the diode bridge to be an X2 rated one. (in an offline SMPS)
I mean, surely it could be a ceramic and non X2 rated?..so what if it fails short….there’s a fuse upstream of it.
So is ceramic OK for AC filters in offline SMPS (upstream of the diode bridge)?
You can find a million internet reports on X2 capacitors…eg...
https://ac-dc.power.com/system/files...-docs/an15.pdf
..but none of them state if it’s an actual regulatory requirement for a capacitor from line to neutral upstream of the diode bridge to be an X2 rated one. (in an offline SMPS)
I mean, surely it could be a ceramic and non X2 rated?..so what if it fails short….there’s a fuse upstream of it.
So is ceramic OK for AC filters in offline SMPS (upstream of the diode bridge)?
Mains supply is not a pure sinewave.
It has many other frequencies superimposed on it.
Some of these other frequencies have an amplitude that can exceed 1500Vpk
What ever you hang on that supply must be able to tolerate these high voltage spikes.
X and Y rated capacitors are specifically designed and manufacturered to tolerate these HV spikes.
It has many other frequencies superimposed on it.
Some of these other frequencies have an amplitude that can exceed 1500Vpk
What ever you hang on that supply must be able to tolerate these high voltage spikes.
X and Y rated capacitors are specifically designed and manufacturered to tolerate these HV spikes.
Using X caps is best practice. You should ask a lawyer or insurance company if doing less than best practice is acceptable. I think I can guess what they will say. Whether regulations require X caps is a separate issue.
As others have said: emphatically yes you must - for all the good reasons stated above, but one word of warning. I think you should stay away from Rifa X2 PME series. Electrically they were/are superb, no doubt, but the housing cracks over time and then they are suddenly not so good. If you google pictures of Rifa X2 PME series you''ll see what I mean. (Revox used them in the electronics that controls the motors of their taperecorders - and they fail very frequently. I have also used them in a mains filter with the same result). But newer Rifs do not have the same problem.
Ahem, did you read the document you are referencing?
Page 5 states (my emphasis):
And page 8+9 are basically devoted to selecting the proper caps for EMI-filtering, starting with:
So that is your regulatory requirement as far as I can see? 😀
/U.
Page 5 states (my emphasis):
And page 8+9 are basically devoted to selecting the proper caps for EMI-filtering, starting with:
So that is your regulatory requirement as far as I can see? 😀
/U.
Thankyou…
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The “European requirement EN 132400 for safety” standard document costs about £100 and we cannot afford this, or any of the other many thousands of similarly priced standards.
We have no way of knowing whether EN132400 document says that the AC mains filter capacitors should be X2 rated or not. Does anybody know?
Thanks, but our enclosure has no ventilation holes, and exploded fragments won’t manage to get out of the 1.5mm thick Perspex enclosure. We also have a 1.6A fuse at the upstream and of the product.
Thanks, but if we use a 1.5kV, 100nF, non-X2 rated ceramic capacitor instead of a 100nF X2 rated capacitor, then the ceramic’s 1.5kV rating will never get breached because our MOV won’t let through any more than 1kV when a transient happens.
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The “European requirement EN 132400 for safety” standard document costs about £100 and we cannot afford this, or any of the other many thousands of similarly priced standards.
We have no way of knowing whether EN132400 document says that the AC mains filter capacitors should be X2 rated or not. Does anybody know?
But fortunately you don't have to spend a penny or even procure the standard itself, you just have to spend a minute reading the very document you linked to yourself 😱
from page 8 said:
...and footnote #13 refers to the actual standard.
So there, completely without any financial investment on your part we have established that the answer to your original question is "Yes, there is a regulatory requirement to use X-type capacitors for EMI filtering" 😉
/U.
EDIT: In anticipation of another question: Could you be stupid and put in a cheaper HV ceramic type instead to save on the BoM-cost of whatever product you are designing? Yes, of course you could, but this would mean that you would be unable to get safety approvals for your product and therefore not legally be allowed to sell it. If you do that anyway and anyone manages to damage people or property with your substandard product, that would leave you open to some serious lawsuits (even outside of the US).
If you do decide to do this, then in lieu of consulting fees for our advice please publish the name of your company/product so at least the people that tried to advice you can stay clear of any substandard results 😉
The above is very sarcastic, but safety standards exist not only to make your life harder but actually for protection of everyone, so they should not be ignored.
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Any chance you could tell us the name of the product/company this is associated with?
Just want to make sure I avoid anything you make, your ability to listen to sound advice seems contrary to your ability to ask for it.
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There is some confusion here between a regulation and a standard.
A regulation says you must do this or we can fine you or perhaps send you to jail.
A standard instructs one on the minimal accepted practice or a method to do something. Standards are often adopted and then become law.
However if you do work differently than a standard specifies you have given your insurance company a reason not to pay claims. You also can be sued for significant sums following a failure. Of course one of the contributing factors in a court case is intent. Which you have nicely demonstrated here.
Now the folks who write standards have in mind the least expensive method to meet the goals which in this case is safety.
So no you don't actually have to use a rated capacitor.
You also are allowed to jump off a tall building. Although in many places the results of the landing are unapproved.
You might want to wiki a word that may be new to you "Stupiditiy."
A regulation says you must do this or we can fine you or perhaps send you to jail.
A standard instructs one on the minimal accepted practice or a method to do something. Standards are often adopted and then become law.
However if you do work differently than a standard specifies you have given your insurance company a reason not to pay claims. You also can be sued for significant sums following a failure. Of course one of the contributing factors in a court case is intent. Which you have nicely demonstrated here.
Now the folks who write standards have in mind the least expensive method to meet the goals which in this case is safety.
So no you don't actually have to use a rated capacitor.
You also are allowed to jump off a tall building. Although in many places the results of the landing are unapproved.
You might want to wiki a word that may be new to you "Stupiditiy."
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The ability of a capacitor to withstand constant AC stress is not just a matter of keeping within peak DC voltage rating. Don't ask me why, but that is what is said. X and Y caps are designed to cope with AC.kipper1 said:
Why are you so averse to using the proper cap for the job? Is this your approach to other design details? Will you next be asking us if it is OK to relax the creepage/distance requirements for mains voltage, or ignore the EMC requirements and flatten TV sets in the next road?
The other thing is, since X and Y-rated caps are made and sold by the tens of million, widely available from many reputable manufacturers (with a vested interest in not being sued for failures ) - these parts are very cheap, for a cap with the proven capability/required graceful failure mode.
Why would you not use one..?
Why would you not use one..?
WHY does he ask if he disregards safety advice and will do whatever he originally wanted anyway?
Waste of bandwidth and Members time.
Waste of bandwidth and Members time.
If your business cannot afford £100 and you are trying to pinch pennies on mains caps then you should probably just shut it down.
Perhaps the forum should ask for a contribution from people seeking pro bono consultancy for commercial purposes. Especially if they appear to have registered for that purpose alone.
Kids should not be playing with this stuff.
Anyway: Certain inherently dangerous topics are not allowed. At this time they include but are not limited to: discussing power supplies directly fed by mains current without a transformer.
Are you an electrical engineer? I'd find that hard to believe. Middle manager would be my guess.
I am repairing an amplifier for a friend and wish to replace some of the mains filter components.....I will indeed use X2 rated capacitors.
Don't fit a replacement capacitor across the ON/OFF switch.
That is often done in commercial equipment to reduce wear on the switch contacts.
It is the wrong place for the capacitor and/or snubber.
The cap/snubber should be across the load that is creating the back emf at the moment of switch OFF.
That is often done in commercial equipment to reduce wear on the switch contacts.
It is the wrong place for the capacitor and/or snubber.
The cap/snubber should be across the load that is creating the back emf at the moment of switch OFF.
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