Mobile Generator/Power Distribution Facility

"Voltswagon" on site at the 2007 DARPA Urban Challenge


Like our Communications trailer,  "Voltswagon" was previously an ABC Television production truck, in fact it is the twin to it. For those of you who are Production trivia buffs, they were ABC Phase 3 and Phase 7.

The roof is covered with diamond plate and is load-bearing, so it can support fixtures to erect site lighting.The trailer was stripped and all cabling and television equipment was removed, along with any unnecessary racks.  We retained the precision voltage regulators and use them to provide two 60A regulated sources for off-board electronics. Each regulator feeds six 20A breakers which in turn feed a multipin Socapex connector and a companion parallel blade (edison) breakout box.

The floor pan in the rear room (formerly engineering and video, now engine room) was removed and replaced with a fluid-tight pan to contain spills in the event of a catastrophic engine failure. 


The rear-most storage bay under the trailer was opened on top to become the intake air plenum for the engine room. The former video tie panel in the curb side of the engine room also opens to become an additional engine room air intake.



The center room (formerly audio) was reconfigured to become the switchgear and transformer room, and the former audio entrance panel is now a camlock panel for all incoming and outgoing switchgear connections. A high flow exhaust blower in the switchgear room draws cooling air through a grille in the camlock panel across the panel cabling and up through the transformers before exhausting it out of a former cable mousehole on the street side.

All switchgear wiring is high-strand-count neoprene jacketed SC type cable for high resistance to vibration fatigue and abrasion.

This photo was taken during a load test, with a 150KW load bank connected to the 200A 480V Delta output.

The Camlock panel is the central bonding point for neutral and ground for the system. Heavy copper buss bar is used with multiple cross-ties between the neutral and ground busses.


The front room (formerly production) has been configured as a site shop with a large bench, drill press, welder, and other on-site fabrication tooling; and is air conditioned.

The racks which separate the engine room from the switchgear room provide a measure of acoustic isolation and contain the custom-built switchgear and the automatic transfer switch for the generator. The switchgear provides for these distribution inputs and outputs:

  • 400 Amp 480V 3 Delta Main input (switchgear can also be fed with 800 Amp 120/208Y source)
  • 200 Amp 480V 3 Branch Output
  • 200 Amp 120/208Y 3 Branch Output
  • 2 - 125 Amp 120/208 3 Branch Outputs
  • 3 - 200 Amp 1 Branch Outputs (two legs of 3)

The engine room houses a 250KW genset with autostart, controlled by the automatic transfer switch. 700 Amp continuous, 800 Amp trip.

The generator features precision voltage regulation, rated at .5%. A 150KW slam load causes no significant droop. 



This system is designed to provide power distribution and backup or short-term (days) prime power to a complex such as a command post or staging area. The generator is quieted but is not silenced. It is not appropriate for movie or TV shoots. 

The trailer can carry up to 3000' of 4/0 SC ultra-flex feeder in 100' lengths with camlocks, as well as several sets of #1 and #2 camlock cable sets. 

A variety 200 amp subpanels are available, including 3-phase and single phase. They are all configured with camlock connectors for their input connections.

Some subpanel configurations are as follows:

  • Loaded with multiple 70A two-pole breakers, rainproof, intended to be used to feed multiple office or other portable site trailers.
  • Loaded with 20A GFI breakers and multiple Edison quad boxes affixed to the exterior, rainproof, intended to provide a multitude of individual circuits.
  • Loaded with 50A two pole breakers which feed 50A range plugs affixed to the exterior, intended to feed RV type trailers or kitchen equipment.

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