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Three Phase VT Kits

ABB Kuhlman three phase oil-filled voltage transformer replacement kits for ABB/Westinghouse APT/LPTs 69 kV-138 kV

Application Background

Going back into the 1960s, Westinghouse/ABB promoted and sold their three phase APT/LPT design for voltages from 69 kV to 138 kV to save substation space and installation cost. This design consisted of three single phase, line-to-ground connected oil-filled voltage transformers physically housed within a unified base housing with three independent angled bushings on the top of the housing, and all secondaries terminated in a common junction box. Many customers and thousands of installations resulted from the sales of these compact design three phase voltage transformers. 

When ABB discontinued the sale of oil-filled instrument transformers and closed the Bloomington, Indiana facility in 1999, the exclusive three phase design VT was no longer offered on the market. With a great many of these products now reaching the end of their functional life, exhibiting signs of oil leaks, or experiencing field failures, users with installed units in service have not had an acceptable replacement device to fit into the compact, single structure mounting of the original APT/LPT. That is, UNTIL NOW...

Product Description

ABB Kuhlman's three phase oil-filled voltage transformer replacement kits allow the users of the APT/LPT three phase configuration to conveniently replace existing three phase housing units with a specialized bracket, hardware and individual oil-filled voltage transformers supplied as a single, all-inclusive kit. This kit provides the necessary mounting format to match existing APT/LPT mounting holes, while insuring adequate electrical clearances for the separate voltage transformers.

The bracket consists of a galvanized steel welded I-Beam arrangement with mounting plates for three separate voltage transformers, slotted mounting holes for alignment to existing support structure, and NEMA 2 hole ground pad for bracket equipment ground. Stainless steel hardware is supplied for the VT attachments to the bracket.All items in the kit are shipped separately and will require site assembly.


System Voltage 

Voltage Ratios 


Thermal Burden 

Three Phase Kit No. 

 69 kV 350/600:1:1  0.3% ZZ each phase 18000 VA Total   J710600T3
115 kV 600/1000:1:1 0.3% ZZ each phase 22500 VA Total   K871000T3
138 kV 700/1200:1:1 0.3% ZZ each phase 15000 VA Total   L741200T3