The Westinghouse UVT-2000 is a load tap changer designed for high-current power transformer applications, rated at 2000 amperes continuous. It uses a transfer switch, selector switch, and reversing switch design broadly similar to other Westinghouse LTCs, but the transfer switch stationary contact is a three-part assembly — Positions 1, 2, and 3 — that must be inspected and assessed together. The higher continuous current rating compared to standard LTCs means that resistive losses at degraded contacts produce more heat, and wear progression at any contact interface can accelerate rapidly once it begins.
The transfer switch stationary contact on the UVT-2000 is divided into three separate components — P1, P2, and P3 — that together form the full stationary contact surface. Each component contacts a different portion of the moving contact arc during a tap change operation. When evaluating wear, all three pieces must be removed and assessed individually. It is not sufficient to inspect only the piece showing the most visible wear — wear distribution across the three components provides information about the contact geometry and whether the moving contact is sweeping the full arc correctly.
When replacing stationary contacts, all three components should be replaced as a set. Installing one new piece with two worn pieces creates a step at the contact boundary that can cause the moving contact to hang during a tap change operation — a partial operation that leaves the transformer in an intermediate tap position. Replace the full three-piece set at the same interval.
The transfer switch moving contact sweeps across the P1/P2/P3 stationary assembly on each tap change. Inspect the moving contact surface for erosion at the arcing zone and verify that the contact arm geometry maintains correct engagement pressure across the full sweep. At 2000A continuous current, a moving contact that is worn to reduced contact area produces a current density at the contact interface high enough to cause accelerated heating even under normal load — this condition will not produce an obvious tap change failure but will show up as elevated temperatures at the LTC compartment under infrared scanning.
The selector switch carries load current at each tap position between operations. The UVT-2000 selector uses a moving finger set that engages a stationary contact at each tap position. Inspect each selector stationary contact for oxidation, surface pitting, and evidence of thermal stress from resistive heating. At rated current, poor contact engagement at a selector position can produce localized heating sufficient to cause contact surface degradation that accelerates with each subsequent operation cycle. Measure contact resistance at each tap position and compare to the baseline. A resistance reading that is elevated at one selector position but normal at adjacent positions identifies the problem contact precisely.
The reversing switch uses a finger assembly that engages separate upper and lower stationary contacts in the raise and lower positions. Inspect both the upper and lower stationary contacts for wear and confirm that the finger assembly reaches full engagement in both positions. A reversing switch that does not reach full engagement presents a high-resistance path at full load current — on a 2000A LTC, the resulting heating can damage the contact surfaces within a short operating period. Test reversing switch contact resistance in both positions as part of every maintenance record.
Operation-count intervals for the UVT-2000 follow the manufacturer’s specification, which accounts for the higher current rating. Higher continuous current accelerates contact wear compared to lower-rated LTCs operating at the same operation count. UnderNERC PRC-005, the six-year maximum calendar interval applies regardless of operation count. Transformers with UVT-2000 LTCs that serve large industrial loads or transmission-level applications should have operation counters checked at every scheduled outage — high-load transformers accumulate operations faster than lower-load units and may hit the count trigger well before the calendar trigger.
Southern Switch supplies UVT-2000 contact components including the three-part transfer switch stationary set. Contact us with your transformer nameplate and operation count for a quote.