Hi folks,
consider this topology for a mains supply EMI filter:
My questions is: do C5 and C9 (1nF) have to be Y-rated or can they be "standard" 630V WIMA film caps? The equipment that this goes into has a 3-lead power supply cable and thus has a connection to PE (mains earth, in this circuit diagram depicted as "GND").
consider this topology for a mains supply EMI filter:
My questions is: do C5 and C9 (1nF) have to be Y-rated or can they be "standard" 630V WIMA film caps? The equipment that this goes into has a 3-lead power supply cable and thus has a connection to PE (mains earth, in this circuit diagram depicted as "GND").
Thanks rayma! Do you happen to know if these have to by Y1 or Y2, when used in a 240V environment?
You are in Germany, so the AC line is 230VAC at 50Hz. I would use Y1, the highest rated Y type.
It would be less likely to break down in the long term.
It would be less likely to break down in the long term.
Y2 is adequate as it is meant for voltages between 150 and 300 V AC. BTW the connection between C5/C9 to GND should be to PE as in the safety ground at the primary use side of PSU's. That will work better than using GND which is the secondary side of PSU's. Oops I see you mention it yourself.
Thanks jean-paul, actually it's just labeled GND in the circuit diagram, in fact it's a direct connection to the PE wire where it connects to the chassis.
The safety ground wire should always have its own separate chassis connection.
The Y2 rating is adequate for commercial, price sensitive 230VAC units, but for DIY I would use
Y1 on your 230VAC line. Here in the USA, I've seen many long term failures of Y3 capacitors,
so I use Y2 types instead on our 120VAC line.
The Y2 rating is adequate for commercial, price sensitive 230VAC units, but for DIY I would use
Y1 on your 230VAC line. Here in the USA, I've seen many long term failures of Y3 capacitors,
so I use Y2 types instead on our 120VAC line.
To be honest I made a snafu and designed the PCB for (non Y-rated) WIMA caps with 7.5mm lead spacing, so now I'm searching for one that will fit in this space as the PCBs are already fabricated. Does anybody have any hints how to search for Y1 rated caps on mouser? It seems the spec neither shows up in the search filters nor in the product name, even when in the category "safety caps". I found a cap that would fit my requirements, but it's "only" Y2: https://www.mouser.de/ProductDetail/Murata-Electronics/DE2E3SA102MA3BT02F?qs=5aG0NVq1C4wOcEZ/8sAONA==
@rayma: did you see these failures with any manufacturer or also with reputable brands like Murata?
@rayma: did you see these failures with any manufacturer or also with reputable brands like Murata?
Choose the voltage and value you want from this list. Most are Y2, but some of those do have 7.5mm lead spacing.
https://www.mouser.com/c/passive-co...ponents/capacitors/safety-capacitors|~Product
No particular brands, but I suspect the triggers would have taken out most of them.
https://www.mouser.com/c/passive-co...ponents/capacitors/safety-capacitors|~Product
No particular brands, but I suspect the triggers would have taken out most of them.
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I'm planning to use a soft start circuit to remotely switch on my whole setup and I plan to implement 3 MOVs as overvoltage protection in this circuit block as well. Do you think that these MOVs could have the potential to ease the stress on the Y caps as well?
And what was the failure mode on the Y caps you expreienced did they just fail open circuit? Or was there visible damage? Were they film caps or ceramics?
EDIT: I plan to use a HRC fuse before the MOVs, I think that's good practice?!
And what was the failure mode on the Y caps you expreienced did they just fail open circuit? Or was there visible damage? Were they film caps or ceramics?
EDIT: I plan to use a HRC fuse before the MOVs, I think that's good practice?!
MOVs could help initially, but they will degrade and will useless after a few years.
The units were ones I built over a period of about 25 years, brought in for routine checkups.
There was at times some visible damage, but most of them had not completely failed (yet).
One, about a year ago, had started smoking pretty heavily. They were films.
The units were ones I built over a period of about 25 years, brought in for routine checkups.
There was at times some visible damage, but most of them had not completely failed (yet).
One, about a year ago, had started smoking pretty heavily. They were films.
OK, thanks so much for your insights so far, I will be on the search for suitable replacements, ideally Y1 that will fit the 7.5mm lead spacing. Hopefully there are some...
The Y2 will work ok, just try to get a 300VAC Y2 rating which seems to be common enough.
Use the filters you want on the Mouser list in post #9. There are many 7.5mm 300VAC Y2 safety capacitors.
Use the filters you want on the Mouser list in post #9. There are many 7.5mm 300VAC Y2 safety capacitors.
No, but some were cracked, some were discolored, and one was smoking.
That's why I prefer Y2 for 120VAC now.
I have a partner in crime and as soon as he sees that there are Y1 and Y2, and Y1 "is better" there will be no rest before a suitable Y1 is found. He's kind of a prefectionist. And rightfully so, these amps we built are not cheap and should last a lifetime if anyhow possible.
I plug all of my own equipment into Tripp LITE filtered power strips, and that seems to have worked well.
There's around 7-8 of them around here. They still have to be checked, and have both MOV and capacitors.
https://www.tripplite.com/isobar-8-outlet-surge-protector-12-ft-cord-3840-joules~isobar8ultra
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Do you happen to know how these accomplish the surge protection? If you're vary of MOVs - do they use spark gaps?
Originally I used Y2 capacitors for our 120VAC but now use Y1 because of the failures seen.
Two units have also been victims of nearby lightening strikes, also taking out both power transformers.