Home appliance electronics for Vietnam need a mains varistor on every power board, and the Walsin Technology (Walsin) catalogue lists 379 of them. The 250 Vac rung alone holds 17 parts spanning 400 A to 80,000 A of peak current, the suffix E sits in two different series, and none of the 379 is on our Hong Kong shelf.
Venatech Limited, an authorised Walsin distributor in Hong Kong, wrote this from the Venatech upload file for Walsin varistors (379 rows, 379 distinct part numbers) and our stock list as at 23 September 2026 (1,125 distinct part numbers). It is for a design or sourcing engineer at a Vietnamese maker of washing machines, refrigerators or other mains appliances who is crossing a metal-oxide varistor. Every part number is real and every count is ours. The market facts name their sources and the day we fetched them, 10 November 2026.
What did Hai Phong report about LG and foreign investment in 2026?
It reported a large foreign-investment base and appliance-maker expansion plans. According to Hai Phong Newspaper on 20 March 2026, the city had attracted 1,038 foreign direct investment projects with 44 billion US dollars of registered capital, and three LG companies at Trang Due Industrial Park, including LG Electronics Vietnam Hai Phong, told the economic zone authority they plan to expand production and launch new product lines this year.
A separate company profile on a Vietnamese business portal lists washing machines, vacuum cleaners and televisions among the products of the LG Electronics complex at the same park. Those are the sources’ statements, not ours. Our reading is ours: a washing machine or refrigerator has a mains input, and the first part after the fuse is usually a varistor. We have no relationship with LG or any Vietnamese maker and say nothing about what any of them buys.
How many Walsin varistors are there, and how are they organised?
Three hundred and seventy-nine, in four series and eleven sizes. We counted the Venatech upload file: 170 Standard (D Series), 101 Industrial, 60 Super High Energy (V Series) and 48 High Energy (E Series) part numbers, in sizes from 5 mm to 53 mm.
The working voltage runs from 11 Vac to 750 Vac. Most rungs hold 17 parts, one for each size and series combination, so a voltage rung is not a single choice. Our post on how to choose an MOV varistor explains the selection method, and the MOV range lists the families.
How wide is the 250 Vac rung in surge current?
Two hundredfold. At the 250 Vac maximum working voltage, with a 390 Vdc varistor voltage, the export lists 17 part numbers whose peak current runs from 400 A for the 5 mm Standard part to 80,000 A for the 34 mm square Industrial part.
The 230 Vac and 275 Vac rungs show the same 17-part, 400 A to 80,000 A spread. Picking by voltage alone leaves a factor of 200 open in the energy the part can take. For a household appliance board the choice sits at the size and series level, and the datasheet, not the export, carries the energy rating.
Does the suffix E mean one series?
No, and that is a trap in a bill of materials. Of the 108 Walsin varistor part numbers ending in E, 48 belong to the High Energy (E Series) in 5, 7 and 18 mm sizes, and 60 belong to the Super High Energy (V Series) in 10, 14 and 20 mm sizes.
So SR391K07E and SR391K10E look like siblings, one step apart in the size code, but they sit in different series with different surge ratings: 1,750 A and 4,000 A. We have not seen this counted anywhere. A buyer who sorts a list by the last letter groups two series together. Read the series name, then the size, then the current.
Which Walsin varistors cross a 250 Vac, 14 mm, 4,500 A brief, and what differs?
Two match and three do not. For a 250 Vac, 390 Vdc, 14 mm brief with at least 4,500 A of peak current, SR391K14D matches on every export field and SR391K14E exceeds it at 8,000 A.
The reader’s incumbent goes in the last column.
| Walsin part | Description | On shelf 23 Sep 2026 | Match / mismatch with the brief | Your incumbent |
|---|---|---|---|---|
SR391K14D |
Standard (D Series), 14 mm, 250 Vac, 390 Vdc varistor voltage, plus or minus 10 percent, 4,500 A | No | Match on size, working voltage, varistor voltage and current | |
SR391K14E |
Super High Energy (V Series), 14 mm, 250 Vac, 390 Vdc, 8,000 A | No | Match on the voltage fields and size; mismatch: 8,000 A, a different series | |
SR391K10E |
Super High Energy (V Series), 10 mm, 250 Vac, 390 Vdc, 4,000 A | No | Mismatch: 10 mm and 4,000 A, below the brief | |
SR391K07E |
High Energy (E Series), 7 mm, 250 Vac, 390 Vdc, 1,750 A | No | Mismatch: 7 mm and 1,750 A | |
SR431K14D |
Standard (D Series), 14 mm, 275 Vac, 430 Vdc, 4,500 A | No | Mismatch: working voltage is 275 Vac, one rung up |
A match in the table is a match on the export fields, no more. Confirm against both datasheets and qualify in your own circuit. The wider surge question is in anti-surge chip resistors, which covers the downstream part.
What does the Hong Kong shelf hold in varistors?
Nothing. Our stock list as at 23 September 2026 holds 1,125 distinct part numbers, and none of the 379 Walsin varistor part numbers is among them.
Every varistor line is therefore a to-order enquiry from us today. That is a fact about our shelf, not about Walsin’s availability, and we make no lead-time promise. The ready stock list is a dated snapshot, never live-synced. Ask us through the site for a to-order quote, with the series and size, not just the voltage.
What will we not tell you about appliance electronics?
Anything about your product’s safety approval, surge test level or fusing. We hold no Walsin datasheet for the varistor line, so every figure in this post comes from the export columns and is flagged for confirmation against Walsin’s published MOV catalogue.
We make no claim that any part suits a washing machine, a refrigerator or any test level. We hold no ISO 9001 or IATF 16949 certificate. We give no legal, customs or conformity advice; confirm with your compliance team. Qualification stays with you.
How can Venatech help a Hai Phong appliance buyer?
How Venatech helps starts with a free paste box. The cross-reference tool, called VenaMatch, decodes 18 manufacturers’ part numbers and covers 800,000+ crossable parts; paste up to 500 part numbers or an Excel or CSV file and each Walsin candidate returns with every field marked match or mismatch. Load a whole BOM for a review. The ready-stock list is a Hong Kong snapshot dated 23 September 2026.
Worked example from our own files: the 250 Vac, 14 mm, 4,500 A brief returned 2 parts that fit among 17 at the rung, none stocked. Venatech Limited is an authorised Walsin Technology distributor in Hong Kong; Stackpole and Viking are lines we supply. We serve from Hong Kong, welcome small lots, and you request a quote through the site.
The short version
For a Vietnamese appliance designer, a mains varistor is a series-and-size question: 379 parts, 17 at the 250 Vac rung spanning 400 A to 80,000 A, a suffix E that covers two series, and nothing on the shelf. Name the voltage, size and peak current, not just the voltage.
Send us one varistor line from your BOM, with the working voltage, size and surge current you can accept, and we will return the Walsin parts with every difference stated. If your incumbent prints only 250 Vac, do you know which of the 17 you are buying?
Sources
Fetched 10 November 2026.
- Hai Phong Newspaper, Facilitating LG’s investment expansion in Hai Phong, 20 March 2026: https://news.baohaiphong.vn/print/538528.html
- Golden Dragon, Vietnam business portal, LG Electronics Vietnam Hai Phong company profile 2025-2026 (undated page): https://goldendragon.vneconomy.vn/doanh-nghiep-98-cong-ty-tnhh-lg-electronics-viet-nam-hai-phong.html
Related reading
- How to choose an MOV varistor
- Anti-surge chip resistors
- MOV varistor series selection: D, E, V and Industrial
- Free cross-reference tool (VenaMatch)
- Ready stock, Hong Kong snapshot dated 23 September 2026
Last reviewed 10 Nov 2026.
Frequently asked questions
How many foreign investment projects did Hai Phong report in March 2026?
Hai Phong Newspaper reported on 20 March 2026 that the city had 1,038 foreign direct investment projects with 44 billion US dollars of registered capital. These are the newspaper’s figures, not ours.
How many Walsin varistors are there?
379 distinct part numbers in the Venatech upload file: 170 Standard, 101 Industrial, 60 Super High Energy and 48 High Energy, from 5 mm to 53 mm. Confirm each against Walsin’s MOV catalogue before design-in.
How many Walsin varistors are rated 250 Vac?
17 part numbers, with a 390 Vdc varistor voltage and peak current from 400 A for the 5 mm Standard part to 80,000 A for the 34 mm square Industrial part. The size and series decide the energy.
Does a part number ending in E mean the same Walsin series?
No. 48 of the 108 E-suffix varistors are High Energy (E Series) and 60 are Super High Energy (V Series). SR391K07E and SR391K10E sit in different series. Read the series name and the current.
Is a 14 mm Standard varistor a drop-in for the 14 mm Super High Energy part?
Not without checking. SR391K14D and SR391K14E share size and voltage fields, but the current is 4,500 A against 8,000 A and the series differ. Confirm against the datasheet and qualify in your own circuit.
Do you hold stock or an office in Vietnam?
No. Our locations are Hong Kong, Shenzhen, Singapore and Jiangmen, with Chengdu in preparation, and none of the 379 varistors is on the shelf. We hold no ISO 9001 or IATF 16949 certificate and give no legal, customs or conformity advice. Confirm with your compliance team.