The SN portable substation at RVJ, SN #1, is the first automatic portable substation built for the electric railway industry (300 kw synchronous covernter, 1920 cost: $18,000). Assembled on a flatcar, the boxcar-like structure was added to protect the apparatus from the elements (the flatcar stake pockets are still bolted to the center sills). It was designed to monitor the third rail voltage and used an undervoltage relay to start whenever the voltage dropped below a certain value for a predetermined amount of time (to sort out momentary voltage fluctuations from the load of an approaching train). First set up at Del Paso, where I-80 crosses the SN right of way, the RR eventually built a permanent installation at this location, the equipment from which is in now at OERM. The Del Paso substation building is now at RVJ, where it houses both a second synchronous converter SN substation in kit form of the same capacity, acquired from the UC Berkeley field station, and the BARTD rectifier (approx 1.2 mw, from the Concord test track). The last RR use of #1 was for powering the overhead on the short piece of track at the WP's Sacramento shops for testing the freight motors when they were brought down from Marysville/Yuba City for servicing.