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Metal Oxide Varistor for Pump Controllers in India: Coimbatore Makes About 10,000 Pump Sets a Day, and Venatech Supplies 379 Walsin Varistors

Coimbatore’s pump makers still turn out about 10,000 pump sets a day, and every controller on a long rural power line needs surge protection. Venatech, Walsin’s authorised distributor in Hong Kong, supplies 379 Walsin metal oxide varistor part numbers, 17 of them rated 275 Vac in disc sizes from 5 mm to 53 mm.

Venatech Limited, an authorised Walsin distributor in Hong Kong, wrote this for engineers and buyers at pump, motor-starter and pump-controller makers in Coimbatore, Tiruppur and across Tamil Nadu. Walsin Technology (Walsin) is the line we are authorised for. The Walsin figures come from our varistor export, Walsin_MOV_ALL.xlsx, which we re-measured on 11 November 2026, and our ready stock list as at 23 September 2026. Every part number below is real.

How big is Coimbatore’s pump industry today?

Still large, and working through a cost squeeze. DT Next reported in March 2026 that Coimbatore’s pump makers produce about 10,000 pump sets a day from about 1,500 manufacturers, down from 25,000 a day and about 3,500 makers a decade ago, as copper rose from 850 to 1,500 rupees a kilogram within six months.

The DT Next report, updated on 16 March 2026 and read on 11 November 2026, quotes the Kovai Power Driven Pumps and Spares Manufacturers Association, the Coimbatore District Small Industries Association and the Coimbatore Tirupur District Micro and Cottage Entrepreneurs Association on raw material costs and GST. An earlier Deccan Herald report of 18 August 2025 put Coimbatore’s share of India’s pump sets at 40 percent, with Gujarat at 35 percent. These are the publications’ figures, not ours.

When margins are this tight, a field return is expensive. A pump controller that fails after one monsoon storm costs a warranty visit to a borewell, often far from town, and the part that prevents most of those visits costs very little.

Why does a pump controller need a metal oxide varistor?

Because the controller sits at the end of a long overhead line. A metal oxide varistor across the mains input of a pump starter, submersible control panel or solar pump drive clamps lightning-induced and switching surges before they reach the rectifier, the relay coil or the motor drive electronics.

The varistor conducts hardly at all at normal mains voltage and conducts heavily above its varistor voltage, diverting the surge current. Two ratings decide the part. Maximum continuous AC voltage must sit above your highest steady mains voltage, with margin for high-voltage rural feeders. Peak surge current, which rises with disc diameter, must cover the surge environment you expect. Our post on how to choose an MOV varistor walks through the selection.

How many Walsin varistors can Venatech supply?

379 distinct part numbers in four series. We counted 379 Walsin metal oxide varistor part numbers in our export: 170 in the standard D series, 48 in the high-energy E series, 60 in the super-high-energy V series and 101 industrial parts, in disc sizes from 5 mm to 53 mm plus a 34 mm square block.

By continuous rating, 184 are rated 275 Vac or more and 99 are rated 420 Vac or more. The 275 Vac family alone runs from a 5 mm disc rated 400 A to a 53 mm disc rated 70,000 A, and the 34 mm square industrial block reaches 80,000 A. That range lets a single-phase controller and a three-phase panel share one supplier.

Brief	Walsin part	Series, disc size	Max continuous AC	Peak current (export)	Match / mismatch	On our shelf, 23 Sep 2026
230 V single phase, compact	`SR431K14D`	D, 14 mm	275 Vac	4,500 A	Match	Request a quote
230 V, higher surge	`SR431K18E`	E, 18 mm	275 Vac	9,000 A	Match; mismatch on footprint against 14 mm	Request a quote
230 V, high rural mains	`SR471K14D`	D, 14 mm	300 Vac	4,500 A	Match	Request a quote
230 V, high mains, 20 mm	`SR471K20D`	D, 20 mm	300 Vac	6,500 A	Match	Request a quote
415 V three phase, line to line	`SR681K20D`	D, 20 mm	420 Vac	6,500 A	Match	Request a quote
415 V, extra margin	`SR751K20D`	D, 20 mm	460 Vac	6,500 A	Match	Request a quote
Panel-level surge block	`SR431K34R`	Industrial, 34 mm square	275 Vac	40,000 A	Match	Request a quote

Walsin varistors were not in our Hong Kong ready stock snapshot as at 23 September 2026, so request a quote and we source them through our authorised Walsin channel. We make no lead-time promise.

Which varistor rating suits a 230 V or 415 V pump panel?

275 Vac or 300 Vac for single phase, 420 Vac or 460 Vac line to line for three phase. We read the part code the same way across all 379 parts: SR431K14D is a 430 V varistor voltage (the 431), plus or minus 10 percent (K), 14 mm disc (14), D series, rated 275 Vac continuous in our export.

On a 230 V feeder that regularly runs high, the 300 Vac SR471 family gives more headroom, at the cost of a higher clamping voltage that the protected circuit must withstand. For a 415 V three-phase starter, place parts line to line and line to earth according to your protection scheme, and choose 420 Vac or 460 Vac between lines. Then size the disc for surge current and repetition: every surge ages a varistor slightly, so a larger disc lasts longer in a lightning-prone area.

How can Venatech help a Coimbatore pump maker?

How Venatech helps is to turn your current varistor list into Walsin crosses in one pass. VenaMatch at /cross-reference/ decodes 18 manufacturers’ part numbers and crosses 800,000+ parts to Walsin, returning every field marked match or mismatch, so a varistor from another brand comes back with its Walsin voltage, disc size and surge rating side by side.

Upload a full BOM at /bom/, browse the varistor range, check the ready stock list (a snapshot as at 23 September 2026, never live-synced), and request a quote through the site. We serve from Hong Kong in small lots with fast quotes, hold no office in India, give no legal, customs or conformity advice, and leave qualification with you.

The short version

Coimbatore makes about 10,000 pump sets a day, per DT Next in March 2026.
Venatech, Walsin’s authorised distributor in Hong Kong, supplies 379 Walsin metal oxide varistors in four series.
17 Walsin parts are rated 275 Vac, from 5 mm at 400 A to 53 mm at 70,000 A; 99 are rated 420 Vac or more.
Choose continuous voltage for your mains, disc size for your surge environment, and confirm clamping and energy on Walsin’s datasheet.

Paste your varistor part numbers into the free cross-reference tool and read each field as match or mismatch.

Frequently asked questions

How many pump sets does Coimbatore make?

Per DT Next in March 2026, Coimbatore makers produce about 10,000 pump sets a day from about 1,500 manufacturers, down from 25,000 a day a decade ago.

How many Walsin metal oxide varistors does Venatech supply?

We counted 379 Walsin varistor part numbers in our export, re-measured on 11 November 2026, across the D, E, V and industrial series. Venatech is Walsin’s authorised distributor in Hong Kong.

Which Walsin MOV suits 230V mains?

The 275 Vac family, codes starting SR431, such as SR431K14D, a 14 mm D-series disc rated 4,500 A in our export. For feeders that run high, the 300 Vac SR471 family adds headroom.

Which varistor suits a 415V three phase pump starter?

Between lines, the 420 Vac SR681 or 460 Vac SR751 families, for example SR681K20D or SR751K20D, both 20 mm and rated 6,500 A in our export.

Does a bigger varistor disc last longer?

Generally yes. Peak surge current and pulse life rise with disc diameter, so a 20 mm disc tolerates more repeated surges than a 14 mm disc of the same voltage. Check pulse-life curves on Walsin’s datasheet.

Can Venatech guarantee varistor stock or lead time?

No. We give no price, lead-time or stock guarantee. Request a quote; we source Walsin varistors through our authorised channel.