Safety Capacitor Certificate Numbers: Five a German Buyer Can Check Without Asking Us

Five. We read all 451 pages of the 28 Walsin datasheets we hold, and exactly five third-party certificate numbers appear in them. Every safety capacitor certificate number sits in an approval sheet, never in a parametric export — which is why no selector, ours included, can show you one.

Venatech Limited, an authorised Walsin distributor in Hong Kong, holds 203 Walsin Technology (Walsin) parametric export files and 28 Walsin datasheets totalling 451 pages. This post is measured from three of those PDFs — 16_Safety_X1Y2_General_S2.pdf, 17_Safety_X1Y2_Automotive_S2_H.pdf and 18_Safety_X2_S3.pdf — plus 00_MLCC_Full_Catalogue.pdf and the MLCC export 00_ALL_MLCC_parts_combined.xlsx. Every part number below is real. Every count is of part numbers and pages, not pieces. A certificate number is the rarest thing a distributor can give an engineer in Germany, because it is the one claim the engineer can disprove in half a minute.

Which five certificate numbers does Walsin print, and where?

We searched the full text of all 451 pages for each number and recorded every page it lands on. Two are TUV certificates, one is a UL file number, and two are CQC certificates. They are not spread evenly: the UL file and one TUV certificate appear on 8 pages each, while the CQC certificate covering the X2 series appears on just 2 pages in the whole library. These certificate numbers are not in the parametric export — they come from Walsin’s approval sheets, which is why no selector can show them to you.

Check us. A UL file number is searchable in UL’s own public database, and E182369 is the fastest way a buyer in Munich or Stuttgart can confirm that the series we are offering is the series that was tested. We have not seen this page-by-page count published anywhere, and it exists only because we went looking for the numbers rather than for the marketing word in front of them.

Why can no cross-reference tool show you a safety capacitor certificate number?

Because the field does not exist. We opened all 203 export files and collected every column header: 96 distinct column names across the whole set, and not one of them names a certificate, a standard, a safety class, an approval or a test edition. The MLCC export carries 16 columns — part number, series, size, dielectric, capacitance, tolerance, rated voltage, L, W, T, termination, packing, SPQ, remark, thickness, symbol — and stops there. Certificate numbers are not in the export and never were, so a selector that filters on “safety certified” is filtering on a series name, not on a certificate.

Our own free cross-reference tool has a “safety certified” filter and it works exactly this way: it matches Walsin’s published catalogue by series, then we send you the approval sheet that carries R50381780 and E182369. The filter narrows the shelf; the certificate number is a document. Anyone whose selector claims a live certificate status for a passive component is describing a field that, in Walsin’s data, is not in the export.

Does the S3 approval sheet name its own CQC certificate?

No, and this is the oddest thing we found. We read all 12 pages of 18_Safety_X2_S3.pdf. The word CQC appears zero times in it. The CQC certificate for the X2 series, CQC20001280136, is printed on page 2 of the S2 sheet and on page 41 of the full catalogue — never on the S3 series’ own document. That certificate number is not in the export either, so the only route to it is the sheet belonging to a different series.

The S3 series has a second gap. We opened 16_Safety_X2Y3_S3.xlsx in Walsin’s MLCC export set and it holds two rows, neither of which is a part number: one reads “Parts listed on Walsin product search: 0”, the other a note that the series has a datasheet but no individual part numbers in Walsin’s searchable database. We checked our master set of 360,078 part numbers: it contains zero S3 codes. The same file also labels the series “Safety Certificated Caps X2/Y3” while the approval sheet says the capacitors are class X2. One of the two is wrong and we will not guess which.

Which edition of UL 60384-14 applies, and does one standard map to one certificate?

It does not, and this is where most write-ups go wrong. Walsin lists three standards jointly against the certificate numbers — EN 60384-14 : 2023, IEC 60384-14 : 2023 and UL 60384-14 — rather than assigning one standard to one certificate. We read the “Test standard” line on all three approval sheets to confirm it. What does differ is the UL edition: the S2 sheets say UL 60384-14 : 2025 (Ed 3.0), and the S3 sheet says UL 60384-14 (Ed 2.0) with no year at all.

Measured across the library, “Ed 3.0” appears on 5 pages in 3 files and “Ed 2.0” on 3 pages in 2 files. If your technical file in Germany cites an edition, cite the one on the sheet for the series you are buying, not the one you read in a blog post about a different series.

What do the export’s own numbers say about an S2 part, and where do they mislead?

We parsed all 173 S2 rows in 00_ALL_MLCC_parts_combined.xlsx. Every one shows a Rated Voltage of 5000 Vdc or 6000 Vdc — 163 and 10 rows respectively — and that figure is the impulse voltage, not the working voltage. The approval sheet labels the same code “Impulse voltage” and gives the real rating as X1 310 Vac, Y2 250 Vac and 1500 Vdc on all models under UL and TUV, and 250 Vac under CQC. This is our finding and we published it on 6 October 2026; it is restated here because a buyer reading only the export would over-rate the part by a factor of twenty.

That last row is a second defect we counted: 7 of the 173 S2 rows carry a value in the Termination column, and all 7 of them hold a tolerance figure rather than a finish. The remaining 166 are empty. So the one column that would tell you whether a safety capacitor has standard or soft termination states a finish on zero of 173 rows. We will not tell you a part is interchangeable with your incumbent. We will show you where it differs.

Can you order the AEC-Q200 safety capacitor from any code we hold?

Not from the data. We hold 17_Safety_X1Y2_Automotive_S2_H.pdf, a 12-page approval sheet for an S2 variant Walsin describes as qualified to AEC-Q200, and its ordering key puts that variant in the termination character — Y or X, the thirteenth character of the code. We then checked every S2 entry in our master set: 168 of them, of which 165 are 12-character catalogue codes, two carry the CT packaging suffix, and exactly one, S252B471K502ZT, names a termination at all. Zero carry Y or X.

So the AEC-Q200 safety capacitor exists as a document and not as an orderable code in anything we hold, and the single code that does name a termination reached us through the Hong Kong stock file rather than the parametric export. Walsin’s own word is “qualified to AEC-Q200” and that is the word we use; we hold no qualification report for any part. The standard itself is covered in what AEC-Q200 actually certifies.

What should a buyer in Germany do with five certificate numbers?

Three things, in this order, and the first one takes thirty seconds. Of the 1,125 part numbers on our Hong Kong stock snapshot as at 23 September 2026, exactly three sit in the safety capacitor line: S242B102K502, S252B222K502 and S252B471K502ZT. That is a small shelf and we would rather you knew its size before you asked.

1. Verify us before you talk to us. Search UL file E182369 in UL’s public database, then ask us for the approval sheet for your exact series and read the certificate line yourself. We hold 28 Walsin datasheets, 451 pages, and they go to your inbox rather than into a brochure.
2. Cross the mains stage in one pass. Paste up to 500 part numbers or drop your Excel or CSV into the free cross-reference tool, filter for safety certified, and read the differences we state rather than the matches we claim.
3. Check what is physically in Hong Kong on ready stock before you commit a production slot — a dated snapshot as at 23 September 2026, not a live feed.

For the class question behind all of this, see X1/Y1 vs X1/Y2 safety capacitors. For what travels with a shipment, see certificate of conformity, lot codes and date codes. The series themselves sit on the Walsin MLCC range page.

The short version

Five third-party certificate numbers appear in the 451 pages we hold, and all five are printed in approval sheets rather than in data. Our 203 export files use 96 distinct column names and not one names a certificate, a standard or a safety class. The S3 series’ own 12-page sheet never mentions CQC and its export file lists zero part numbers. Walsin lists EN 60384-14 : 2023, IEC 60384-14 : 2023 and UL 60384-14 jointly, at Ed 3.0 for S2 and Ed 2.0 for S3. All 173 S2 export rows state the impulse voltage where a reader expects the working voltage. Qualification stays with you.

Send us the mains stage off your BOM and we will come back with the Walsin candidates, the approval sheet that carries the certificate number, and the differences from your incumbent stated line by line. Then go and check the UL file yourself — and if you find a sixth certificate number in a Walsin document we have not read, tell us, because that is a gap in our library and we would rather hear it from you.

Frequently asked questions