 In 1982, the power rating of the mercury arc valve rectifiers was raised by various improvements to 1,600 megawatts.In 1985 two six-pulse valve groups of thyristors were added to increase the voltage to 500 kV per pole for a total differential voltage of 1,000 kV.In 1989 the station was extended on the field east of the highway (called Sylmar East Converter Station), where two new 1,100 ampere, 500 kV 12-pulse thyristor converters were added in parallel with the two existing converters, giving a total transmission power of 3,100 megawatts (3,100 Amperes at +/-500 kV

In 2004, Sylmar East station was upgraded from 1,100 MW to 3,100 MW (rededicated as the Sylmar Converter Station in 2005).