Ross Engineering HAF71NC100ACUW Vacuum Relay Contactor 70KV 250A, Westinghouse WL-23318 Interrupter (RH7G4902E21B20)

Ross Engineering Corp. HAF71NC100ACUW high-voltage vacuum relay contactor, rated 70 KV, built around a Westinghouse vacuum interrupter bottle (type WL-23318). Ross Engineering of Campbell, California builds high-voltage relays, contactors, and voltage dividers for power test and transmission work.

Vacuum relays and contactors in this class switch high-voltage circuits in power utility test labs, high-voltage test sets, X-ray and radar transmitters, capacitor banks, and induction heating equipment. The vacuum interrupter extinguishes the arc as the contacts part, which is what lets a device this size make and break at 70 KV without the contact erosion an air-break device would suffer.

The record covers three units; the photographed unit carries nameplate HAF71NC100ACUW, serial 40219-2, P/N 80117. Legacy catalog reference RH7G4902E21B20 is retained in the title for cross-reference.

Used, sold as-is. Sold as-is, surplus from King Surplus inventory in Del Rio, Texas. Same-day shipping on orders before 3:00 PM CT.

• Manufacturer: Ross Engineering Corp., Campbell, CA 95008
• Model: HAF71NC100ACUW
• Serial: 40219-2
• Part Number: 80117
• Type: High-voltage vacuum relay contactor
• Nameplate voltage rating: 70 KV
• Vacuum interrupter: Westinghouse, TYPE NO. WL-23318, SER. NO. 7804003, marked 337, MADE IN U.S.A.
• Rating conflict, reported not resolved: the Ross nameplate reads 70 KV, while this record's HP / AMP / KW / KVA field (FID 60) carries 100/113 KV. These are most likely an operating rating versus an impulse (BIL) rating, but the nameplate text that would settle it is obscured by an overlapping label in the photographs. Both figures are stated here and neither has been picked over the other.
• Current rating: 250 A, per this record's Amps field (FID 66). The current rating is not legible on the nameplate in the photographs.
• Legacy / catalog reference: RH7G4902E21B20, carried in the item title for cross-reference. It does not appear on the nameplate.
• Factory overall dimensions and factory net weight are not published on the nameplate and are not stated here.

Spec Basis: Verified 2026-09-16 against this unit's own nameplate photographs (Ross Engineering data plate plus the Westinghouse interrupter label, KSC record 2580), cross-checked against Manufacturer (FID 56), Model (FID 57) and Serial (FID 58). The prior entry's "Dimensions: 10 x 10 x 37.5 in" and "Weight: 32 lb" were a copy of our own shipping measurements (FIDs 77, 78, 79, 80), not factory specifications, and have been rewritten.