Solid-state integrated crowbar/circuit breaker system

Solid-state integrated crowbar/circuit breaker system

Thanks to the outstanding efforts of Dr. Dave Phillips, an electrical engineer for Space and Naval Warfare (SPAWAR) Systems Center Pacific (SSC Pacific), a new U.S. Government-developed spin-on technology is making submarine communication more reliable, even as it removes hazardous materials from transmission sites with savings of millions of dollars annually.

Because of the nature of seawater, very low frequency transmissions are the only way to communicate with submarines at speed and depth. The Navy has several Fixed Submarine Broadcast System (FSBS) transmitter sites, which are largely powered by onsite diesel generators and use equipment put into service in the 1960s that utilize technology dating from the 1930s. This includes large vacuum tubes, each of which costs $17,000. Since a single 2-megawatt transmitter utilizes $680,000 worth of tubes, protecting them from power surges or fluctuations is a clear priority.

Until recently, this protection came in the form of the ?ignitron crowbar circuit,? a device that would have looked at home in Frankenstein?s lab. The ignitron is basically a pool of mercury kept warm by standard floodlights. Ignitrons consume large amounts of power, interrupt submarine communications when they fire, and can be the source of frequent and disruptive stress in the power supply system. Although they do protect the tubes, their dramatic circuit breaking causes wear-and-tear on equipment, and has made commercial utilities leery of connecting the broadcast sites to their power grids.

In 2010, Dr. Phillips began working with Diversified Technologies, Incorporated (DTI) of Bedford, Massachusetts, on a possible replacement for the ignitron. Dr. Phillips? familiarity with the problem and his exceptional expertise in high-voltage electronics, dovetailed with DTI?s existing component parts, capabilities, and facilities, sparked the new solid-state crowbar technology to life. The new technology eliminates the use of mercury, protects the expensive vacuum tubes, and virtually eliminates loss of communication with submarines. The new crowbar system also makes circuit interruptions essentially invisible to the power system so local utilities can now allow connection to their power grids.

The solid-state circuit breakers have been tested, proven, and are in production. Once fully in place at all of the tube-type FSBS sites, the Navy expects to save about $20 million annually in reduced energy and maintenance costs?a very impressive return on investment, considering the entire project cost about $325,000. Jettisoning the ignitron and adopting the new-style crowbar circuit is a definite blockbuster story, produced on a shoestring budget.

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