EPRI report-amorphous core transformers show promise

A joint project to develop amorphous steel core distribution transformers was begun in 1983. The initial effort was to construct 25-kVA pad-mounted pre-prototype transformers using a continuous-wound core of cruciform cross section made of one-inch-wide Metglas material. A pilot manufacturing facility was designed and construction completed in the fall of 1985. One thousand 25-kVA pole-mounted, 7620/13200-Y-120/240 V, 60-Hz units were produced. The transformers were placed in field trial on the distribution systems of 90 different EPRI member utilities. These field trials are described, and the results are presented. There have been no failures that can be attributed to the amorphous cores. While not all test data have been received, all development testing and field data confirm that the transformers are reliable and the losses stable.<>