Surge Protection Components for Sweden: Where Walsin’s Varistor Range Starts

Choosing surge protection components for Sweden means working inside one hard boundary. Of the 379 varistors Walsin Technology (Walsin) publishes, all 209 in the High Energy, Super High Energy and Industrial series are rated 130 Vac or above. Every one of the 62 parts below 130 Vac is Standard series.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds Walsin’s varistor parametric export of 379 rows. This post is written from that file and nothing else. Every part number below is real and every count is a count of part numbers, not pieces. Sweden’s telecom and grid equipment work sits at two very different voltages — a 48 V DC rail inside a cabinet and a 230 V AC mains feed into it — and the catalogue behaves completely differently at each.

Does Venatech have a Swedish entity or Swedish stock?

No. The operating entities are Venatech Limited in Hong Kong, the Shenzhen trading entity, VENATECH PTE LTD in Singapore and the Jiangmen factory in Guangdong, with Chengdu in preparation. Hong Kong is the authorised Walsin distribution entity and the origin for any Swedish ship-to. There is no Swedish office, no Swedish warehouse and no local inventory.

That is worth saying plainly, because it changes which questions are worth asking us. We cannot offer you a next-day pull from Stockholm. We can tell you what is in the catalogue, what the catalogue does not state, and what is physically on a Hong Kong shelf on a given date.

What can a Swedish engineer actually select below 130 Vac?

Disc diameter, and nothing else. Below 130 Vac maximum working voltage there are 62 part numbers in the whole export and every single one of them is Standard (D Series). The High Energy, Super High Energy and Industrial series do not exist down there.

A 48 V telecom rail with headroom lands around 60 Vac to 75 Vac on the varistor’s working voltage column. At 60 Vac the catalogue offers exactly five part numbers.

Part number	Size	Varistor voltage	Peak current	Series	Match / mismatch vs an energy upgrade
SR101K05D	5 mm	100 Vdc	400 A	Standard (D Series)	Mismatch — no High Energy part exists at 60 Vac
SR101K07D	7 mm	100 Vdc	1,200 A	Standard (D Series)	Mismatch — no Super High Energy part exists at 60 Vac
SR101K10D	10 mm	100 Vdc	2,500 A	Standard (D Series)	Mismatch — no Industrial part exists at 60 Vac
SR101K14D	14 mm	100 Vdc	4,500 A	Standard (D Series)	Match — the largest 60 Vac part but one
SR101K20D	20 mm	100 Vdc	6,500 A	Standard (D Series)	Match — the highest peak current at 60 Vac

Five parts, five diameters, 400 A to 6,500 A. If 6,500 A is not enough at 60 Vac, the answer in this catalogue is not a bigger energy grade — it is a different topology, two devices, or a different manufacturer. The same five-size, one-series pattern holds at 50 Vac, 75 Vac and 95 Vac. At 120 Vac a 25 mm Standard part appears and the count goes to six.

Unique to Venatech’s data. The 130 Vac line is absolute in Walsin’s 379-row varistor export. All 48 High Energy parts, all 60 Super High Energy parts and all 101 Industrial parts — 209 in total — are rated 130 Vac or higher, and all 62 parts rated below 130 Vac are Standard (D Series). There is not one exception. The series selection a designer thinks they are making is unavailable on a low-voltage DC rail, and the export gives no hint of the boundary unless you cross-tabulate the series column against the working voltage column.

The series decode itself is in MOV varistor series selection: D, E, V and Industrial.

Where does the catalogue open up, and how wide does it get?

In a band, and only in a band. Thirteen of the 35 voltage steps in the export publish all eleven disc sizes, and all thirteen sit between 130 Vac and 420 Vac. That band holds 221 of the 379 part numbers.

Working voltage	Varistor voltage	Part numbers	Disc sizes offered	Peak current span
11 Vac	18 Vdc	4	4	100 A – 1,000 A
60 Vac	100 Vdc	5	5	400 A – 6,500 A
120 Vac	180 Vdc	6	6	400 A – 18,000 A
130 Vac	205 Vdc	17	11	400 A – 80,000 A
230 Vac	360 Vdc	17	11	400 A – 80,000 A
420 Vac	680 Vdc	17	11	400 A – 80,000 A
460 Vac	750 Vdc	13	9	2,500 A – 80,000 A
575 Vac	950 Vdc	3	2	40,000 A – 80,000 A
750 Vac	1181 Vdc	1	1	70,000 A only

Inside the band every step is the same shape: seventeen part numbers, eleven footprints, sixteen distinct peak currents from 400 A to 80,000 A. That is a 200:1 ratio of surge capability at one fixed working voltage, which is as much freedom as this catalogue ever gives you. A 230 V Swedish mains input sits squarely inside it, at 230 Vac and 360 Vdc.

Outside it the choice narrows fast. One step, 195 Vac at 300 Vdc, is short even inside the band: it publishes 14 parts across 8 sizes because three Industrial footprints skip it.

Can I calculate the working voltage from the varistor voltage?

No. The pairing is fixed but the ratio is not. Across all 379 rows there are exactly 35 working-voltage values and 35 varistor-voltage values and the mapping between them is strictly one to one — no varistor voltage ever appears against two working voltages. But the implied ratio moves.

Part number	Max working voltage	Varistor voltage	Ratio	Match / mismatch vs a flat 0.64 rule
SR681K05D	40 Vac	68 Vdc	0.588	Mismatch — the lowest ratio in the file
SR181K05D	120 Vac	180 Vdc	0.667	Mismatch — the highest ratio in the file
SR361K14D	230 Vac	360 Vdc	0.639	Match — close to the usual figure
SR431K14D	275 Vac	430 Vdc	0.640	Match — close to the usual figure
SR112K10D	680 Vac	1068.5 Vdc	0.636	Match — but note the fractional varistor voltage

Unique to Venatech’s data. The working-voltage to varistor-voltage ratio in Walsin’s varistor export is not constant. It runs from 0.588 on the 40 Vac / 68 Vdc pair to 0.667 on the 120 Vac / 180 Vdc pair, a 13 per cent spread across the 35 pairs. Deriving one column from the other with a single multiplier will put you a voltage step wrong at both ends of the range. Separately, 1068.5Vdc is the only non-integer varistor voltage anywhere in the file; it appears on 13 part numbers, all at 680 Vac, and it is the kind of value that a numeric import rounds without telling you.

Which disc sizes run out before the voltage does?

The two smallest and the one largest. The 5 mm and 7 mm discs stop at 420 Vac, while 10 mm, 14 mm, 18 mm, 20 mm, 25 mm, 32 mm, 34 mm square and 40 mm all reach 680 Vac. The 53 mm disc is the only footprint that reaches 750 Vac, and it does so with a single part number, SR122K53D, at 70,000 A.

For a Swedish grid or telecom cabinet that is a layout constraint, not a specification constraint. If the board has room only for a 7 mm disc, the working voltage ceiling is 420 Vac and the peak current ceiling is 1,750 A on the High Energy part. Both numbers are properties of the footprint, not of the application.

Do you hold a Walsin varistor datasheet?

No, and that matters for everything above. Venatech holds no Walsin MOV datasheet and no public datasheet URL for this line. The 26 MLCC and 2 chip resistor datasheet PDFs we hold do not cover varistors. Every figure in this post is read out of Walsin’s parametric export.

What does Venatech add for a buyer in Sweden?

Three things a catalogue page cannot. First, the counts above: the 130 Vac boundary, the thirteen full-width voltage steps and the ratio spread only appear when the whole file is cross-tabulated, and no selector on a manufacturer’s website does that for you. Second, an honest statement of what we do not hold, so you know which numbers need a certificate behind them before they reach a drawing. Third, a dated snapshot of what is physically in Hong Kong, so the availability conversation and the selection conversation happen once rather than twice.

We will not tell you a part is equivalent. We will show you where it differs, field by field, and the qualification decision stays with you. The varistor range is on the Walsin varistor range page, and the Hong Kong position is described in Walsin passive components: Hong Kong stock.

The short version

Below 130 Vac Walsin’s varistor catalogue is one series and 62 part numbers, so a 48 V telecom rail can be upgraded by diameter only. From 130 Vac to 420 Vac it is seventeen part numbers at every step, eleven footprints, and a 200:1 spread of peak current. Above 460 Vac it narrows to nine footprints, then to two at 575 Vac and one at 750 Vac. The working-voltage ratio is not a constant you can multiply by. And we hold no datasheet for any of it.

Tell us the rail voltage and the board area you have, and we will tell you which part numbers exist at that intersection and which ones do not. For a Swedish ship-to, ask for the delivery term and the lead time in the same message, because everything moves from Hong Kong.

Faster than an email. The cross-reference tool takes a pasted list or a spreadsheet and returns Walsin candidates field by field, differences included. Ready stock shows what is physically in Hong Kong as a dated snapshot, so you can see whether a line is a stock pull or a production slot. Qualification stays with you.

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Frequently asked questions

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Three ways to get this answered today

1. Cross a part, free. Paste up to 500 part numbers, or drop an Excel or CSV file, into the free cross-reference tool. It is matched against Walsin’s published catalogue and returns candidates field by field, with every difference from your original stated rather than hidden. Filter by commercial or automotive grade, or for soft termination, high temperature, safety certified, high Q / low ESR or low profile. There is no login and no charge.

2. Send the whole BOM. Upload a BOM and request a quote and we will come back line by line — including the lines we cannot help with, which is usually the more useful half of the answer.

3. Check the shelf before you commit. Ready stock shows what was physically in Hong Kong as at 23 September 2026. It is a dated snapshot, never a live feed, and quantities are never permanent.

Why take our word for any of this? Don’t — check it.

Venatech Limited (威納電子有限公司) is an authorised Walsin Technology distributor in Hong Kong. Confirm that with Walsin rather than with us. On the safety capacitor series we hold UL file E182369, which is searchable in UL’s own public database, together with TUV certificates R50381780 and R50195920 and CQC CQC20001280137 and CQC20001280136, against EN 60384-14:2023, IEC 60384-14:2023 and UL 60384-14. We hold 28 Walsin datasheets, 451 pages, and we will send the one covering your part number. Shipments arrive in original sealed Walsin packaging with lot and date-code traceability, and a certificate of conformity is available per shipment on request.

We will also tell you what we do not hold, which no competitor publishes. REACH, SVHC, conflict minerals, PFAS, China RoHS, ISO 9001, IATF 16949, PPAP, IMDS and a Declaration of Conformity appear nowhere in those 451 pages. You would rather hear that from us now than from your own supplier-approval team later. AEC-Q200 is compliant in Walsin’s own words and never certified, we hold no manufacturer’s end-of-life or allocation list for any brand, and qualification in your own circuit stays with you. We will not tell you a part is equivalent. We will show you where it differs.

Venatech Limited · Unit 207, 2/F, Sun Ling Plaza, 30 On Kui Street, Fanling, N.T., Hong Kong · (852) 2628 4777 · Hong Kong, Shenzhen, Singapore and Jiangmen, with Chengdu in preparation.