Industrial Automation Electronics for Austria: A 400 V Three-Phase Line Needs the 460 Vac Varistor Rung, and All 82 Walsin 5 mm and 7 mm Discs Stop at 420 Vac, None of the 379 on the Shelf

Industrial automation electronics for Austria hit a size wall at the mains input. A 400 V three-phase line plus 10% reaches 440 V, and all 82 Walsin 5 mm and 7 mm varistor discs stop at 420 Vac. The 460 Vac rung starts at 10 mm, and none of the 379 rows is on our shelf.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds the Walsin Technology (Walsin) varistor export of 379 part numbers. This post is for a design engineer or buyer at an Austrian maker of drives, controllers, power supplies or control panels who wants to know what a Hong Kong source can offer at the three-phase mains input. Every part number below is real and every count is ours. We hold no datasheet for any Walsin varistor, so every electrical statement here comes from the export and our own arithmetic, and we say so where it matters.

How big is Austria’s electrical and electronics industry, and why does a surge part matter to it?

It is a large, export-led sector, and its products sit on industrial mains. Advantage Austria, citing the electrical and electronics association FEEI, gives 2025 production of EUR 23.6 billion, exports of EUR 19.7 billion and 71,932 employees. We read the page on 22 October 2026; it shows a last-update date of 15 July 2026.

A report by the Vienna Chamber of Labour (status February 2026) adds that order intake for January to October 2025 rose 11.1% to EUR 19.0 billion, and that more than 80% of orders come from abroad. It carries no separate figures for automation or drives, and nor does this post: we have found none that we could source. What follows is our own reading. A product sold abroad meets many mains systems, and the mains-input surge part is one of the few passives whose rating is set by the supply and not by the circuit.

Which varistor rung does a 400 V three-phase supply need?

One rung above the highest continuous voltage the part will see, and on a line-to-line connection that is a higher rung than most catalogues lead with. We parsed the Max Working Volt. field of all 379 rows: it holds 35 distinct values, and the rungs near mains run 250, 275, 300, 320, 390, 420, 460, 485, 510 and 550 Vac. Take 400 V line-to-line plus 10%, which is our assumption, and the figure is 440 V.

The 10% allowance is ours, not a rule. Your supply specification may differ, and a 480 V installation moves every figure up. The arithmetic is the point: 230 V line-to-neutral plus 10% is 253 V, which the 275 Vac rung covers. The same allowance on 400 V line-to-line is 440 V, which the 420 Vac rung does not cover, and the next rung is 460 Vac.

Connection (our arithmetic)	Highest continuous voltage	Lowest rung that clears it	Parts at that rung	Disc sizes at that rung	Peak current at that rung (export)	On the shelf 23 September 2026	Match / mismatch
Line to neutral, 230 V + 10%	253 V	275 Vac	17	5 mm to 53 mm	400 A to 80,000 A	0	Match on rung; shelf none
Line to line, 400 V + 10%	440 V	460 Vac	13	10 mm to 53 mm	2,500 A to 80,000 A	0	Match on rung; mismatch if you wanted a 5 mm or 7 mm disc
Line to line, 400 V + 10%, read at the 420 Vac rung	440 V	420 Vac	17	5 mm to 53 mm	400 A to 80,000 A	0	Mismatch: 20 V under the stated need

Our post on the 127 Vac supply that clears a 140 Vac step by 0.3 V shows the same trap on the low side. What is new here is the size cut-off that the 460 Vac rung brings with it.

Why do the 5 mm and 7 mm Walsin discs drop out?

Because the two smallest disc sizes were never made above 420 Vac in this export. We counted 41 rows at 5 mm and 41 at 7 mm, 82 in all, and the highest Max Working Volt. in either size is 420 Vac. The export holds 82 rows at 440 Vac or more, and the smallest disc among them is 10 mm.

Put the two counts side by side and the shape is clear: 297 of 379 rows sit at 420 Vac or below, in every size from 5 mm to 53 mm, and 82 sit at 460 Vac or above, in sizes from 10 mm to 53 mm. We have not seen this counted anywhere: a 400 V line-to-line design that wants a 7 mm disc has no Walsin part to cross to, and the first step up is a 10 mm disc at 2,500 A in the Standard D series. The 460 Vac rung itself holds 13 part numbers, 4 Standard D, 1 High Energy E, 3 Super High Energy V and 5 Industrial. The 575 Vac and 750 Vac rungs are thinner still, with 3 parts and 1 part.

The disc size is not only a footprint. Peak current climbs with it, from 2,500 A at 10 mm to 70,000 A at 53 mm in the Standard D and Industrial series at 460 Vac, so a larger disc buys surge capacity as well as board area. The export gives a peak current figure but no pulse waveform and no test current for the varistor voltage, and we hold no varistor datasheet that would say. Treat those two fields as unconfirmed until you have Walsin’s sheet.

Which Walsin varistors cross a 460 Vac line-to-line requirement?

Four candidates match on working voltage at a 10 mm disc or above, and two near-misses show what you give up. Say your board has a 460 Vac varistor on a three-phase input, and you want the Walsin parts nearest to it. Varistor voltage is stated as Vdc in the export and tolerance is plus or minus 10% on every row below.

Walsin part	Series	Disc size	Max working voltage	Varistor voltage	Peak current (export)	In stock 23 September 2026	Match / mismatch (460 Vac, line to line)
SR751K10D	Standard D	10 mm	460 Vac	750 Vdc	2,500 A	No	Match on voltage; smallest disc at this rung
SR751K10E	Super High Energy V	10 mm	460 Vac	750 Vdc	4,000 A	No	Match on voltage and disc; higher peak current than the D part
SR751K14D	Standard D	14 mm	460 Vac	750 Vdc	4,500 A	No	Match on voltage; mismatch on disc size if 10 mm is your footprint
SR751K32D	Industrial	32 mm	460 Vac	750 Vdc	30,000 A	No	Match on voltage; mismatch on footprint, a panel-mount class part
SR681K10D	Standard D	10 mm	420 Vac	680 Vdc	2,500 A	No	Mismatch: 40 V under the rung, same disc
SR681K05D	Standard D	5 mm	420 Vac	680 Vdc	400 A	No	Mismatch: 40 V under, and a 5 mm disc with about a sixth of the surge figure

Two things follow. Moving from SR681K10D to SR751K10D costs nothing in disc size and keeps the export’s peak current the same at 2,500 A, so a design that was 420 Vac on a 10 mm disc can often move up one rung without a footprint change, which is a layout fact and not a qualification result. Moving from a 5 mm part does not work that way: the footprint grows. Our post on how to choose an MOV varistor sets out the other fields to read, and the varistor range lists the series.

What do we hold in stock, and what do we not hold for varistors?

Nothing on the shelf, and no datasheet. We counted our stock list as at 23 September 2026, 1,125 part numbers: none is a varistor, so none of the 82 rows at 440 Vac or more is held, and none of the 28 Walsin datasheets we hold, 451 pages, covers a varistor. The datasheets we hold cover MLCC and chip resistors.

A varistor is therefore a factory order from Walsin, and we do not state a lead time. The ready stock page shows the Hong Kong list as a dated snapshot, never live-synced, and we quote part-number counts, never piece counts. We hold no certificate for a varistor, no approval listing for one and no ISO 9001 or ISO 13485 for Venatech, and we do not claim any. If your control-panel standard or your customer asks for an approval mark on the varistor, ask us for what Walsin can supply and confirm it with your compliance team.

How can Venatech help an Austrian automation maker?

By crossing the varistor you already use, stating the differences, and telling you what is missing. Venatech Limited is an authorised Walsin distributor in Hong Kong. Walsin is our only authorised line, and the other lines we supply are Stackpole and Viking.

• Cross-reference. Paste your incumbent number into the free cross-reference tool, which decodes 18 manufacturers’ part numbers across 800,000+ crossable parts, and read each Walsin candidate with match and mismatch stated field by field.
• BOM check. Upload a drive, controller or power-supply bill of materials to /bom/ and have each line checked against the same engine.
• Ready stock. The ready stock list is a Hong Kong snapshot dated 23 September 2026, never live-synced.
• Service. Hong Kong-based, small lots, cross-referencing help, and a quote requested through the site. Our address is Unit 207, 2/F, Sun Ling Plaza, 30 On Kui Street, Fanling, N.T., Hong Kong, telephone (852) 2628 4777.

A worked example from our own export: a 460 Vac, 10 mm varistor on a three-phase input maps to SR751K10D and SR751K10E, neither stocked, and the 420 Vac SR681K10D is a voltage mismatch. Confirm the varistor voltage, peak current and test conditions against the Walsin datasheet, qualify in your own circuit, and treat the 10% allowance as your decision.

The short version

Austria’s electrical and electronics industry produced EUR 23.6 billion in 2025 and exported EUR 19.7 billion, according to FEEI figures on Advantage Austria. At a 400 V three-phase input, our 10% arithmetic gives 440 V, which needs the 460 Vac rung: 13 of 379 Walsin rows, smallest disc 10 mm, because all 82 of the 5 mm and 7 mm discs stop at 420 Vac. None is on the shelf and we hold no varistor datasheet.

Send us the varistor from one drive or control-panel input and we will return the Walsin parts with the differences stated. When your mains input moves up one rung, which gives way first, the footprint or the surge figure?

Sources

Fetched 22 October 2026. The industry statements above are taken from these pages; the part data comes from our own Walsin export and stock list.

• Advantage Austria, “Electrical, electronics and mechatronics: facts and figures” (FEEI figures for 2025, page last updated 15 July 2026): https://www.advantageaustria.org/gb/zentral/branchen/elektro_elektronik_mechatronik/zahlen-und-fakten/zahlen-und-fakten.en.html
• Arbeiterkammer Wien, “Branchenreport Elektro und Elektronikindustrie 2026”, status February 2026: https://wien.arbeiterkammer.at/service/studien/WirtschaftundPolitik/branchenanalysen/Branchenanalyse_FEEI_2026.pdf

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Frequently asked questions

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