Project Details

TransBay Cable
Cupertino Electric utility project for TransBay Cable in San Francisco, California
Pittsburg and San Francisco, CA
Project Size: 
400 MW capacity at 200 kV DC

From Pittsburg to Potrero Hill, Cupertino Electric delivered high quality technical services on this fast project without a single injury. Its ability to successfully execute large- scale, technically challenging and unique electrical projects on time and on budget is amazing.

Markus Becker, Siemens Power & Distribution
Project Summary: 

In September 2007, TransBay Cable, LLC, hired Siemens to supply two converter stations for a new submarine HVDC transmission link running from Pittsburg to San Francisco, California. Shortly thereafter, Siemens chose Cupertino Electric as the project’s electrical contractor to construct the very first HVDC PLUS project in the world linking Pittsburg and San Francisco, Calif. using the Siemens HVDC PLUS and Prysmian XLPE HVDC cable systems. The project was the first of its kind in the world using a multi-level VSC converter system. 

Buried in a safe corridor beneath the Bay away from existing AC cables, the DC cables reduce grid congestion in the East Bay and Peninsula and boost the overall reliability of the utility power system and allow less-reliable and less-efficient generation in San Francisco to be de-commissioned. This critical power transmission infrastructure project now provides sixty percent (60%) of the power needs for the City of San Francisco. 

Cupertino Electric served as prime contractor on the project and installed the AC and DC yards at the Pittsburg and San Francisco sites, the reactor yards, the transformers and the converter hall, as well as provided and installed all structural steel, bus work and insulators. 

CEI's scope of work included: 

  • Procuring and installing all copper and fiber control cables for the converter hall
  • Installing 0.6-mile underground AC cable connecting the Pittsburg PG&E power plant to 400 MW
  • Erecting and installing the converter module (Power module) 
  • Installing the 230 kV AC substation yard, 115 kV AC substation yard, 200 kV +/- DC yard
  • Laying underground AC cable  
  • Installation of all cable raceways, high voltage bus system and 2580 Power Modules (IGBTs) at both Pittsburg and San Francisco sites

Following completion of the project, Cupertino served in a consulting role to provide additional post-construction maintenance and operations services to Siemens.

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