Operational Relevance
On April 8, 2014, Deputy Assistant Secretary of the Navy for Research, Development, Test & Evaluation Mary E. Lacey spoke before the Senate Armed Services Subcommittee on Emerging Threats and Capabilities about the value and positive results of investments in internal research and development efforts at Navy labs.
One example Lacey cited was a Space and Naval Warfare Systems Center Pacific (SSC Pacific) Naval Innovative Science and Engineering-funded project, led by Dr. Dave Phillips, which developed a solid-state crowbar replacement circuit currently being transitioned to Fixed Submarine Broadcast Systems (FSBS) transmission sites.
Lacey said, “We are mindful of the need to affordably modernize our systems and reduce the workload on our Sailors and Marines. The Navy’s very low frequency (VLF) transmitters are located around the world and provide the Navy with the capability to communicate over large distances, one way, to our submarines while they are submerged.
“The problem with the system is it was put into place in the 1960s with technology that dated from the 1930s. It is very expensive to maintain and many of the parts no longer exist. Once the crowbar is implemented at all six VLF sites, the Navy will save $20 million a year in energy and maintenance costs on that alone.”
Technological Solution
Phillips and his team needed to update a heavy-duty electronic component called a “crowbar” in VLF transmitters that deliver messages to Navy submarines around the globe. The transmitters contain gigantic vacuum tubes worth $17,000 apiece. Blowing a bank of them costs the Navy more than half a million dollars.
Phillips, a subject matter expert for SSC Pacific Enterprise Communications for High Voltage and Power Systems and an adjunct professor at San Diego State University, works in the fixed very low frequency (FVLF) arena performing high-voltage design and testing and works as a systems expert for high voltage, power and transmitters for the FSBS Transmitter In-Service Engineering Agent (ISEA).
Phillips is also an SME for Space and Naval Warfare Systems Center Atlantic (SSC Atlantic) in FSBS transmitters and is uniquely positioned to understand the FSBS high voltage system from the power plant to the antenna.
Phillips came up with the solid-state crowbar — or circuit breaker — to protect the tubes without creating power problems for adjacent power grids and nearby towns.
Phillips’ innovation, the Crowbar Replacement Circuit, replaces and improves 1930s ignitron technology with state-of-the-art solid state power electronics and controls to make several improvements and cost-saving steps for the Navy. The Crowbar will replace older mercury-filled ignitron technology with an energy efficient, solid-state circuit which will protect commercial power, generators and transmitters from high energy arcs in VLF transmitters and associated circuits. The Crowbar allows connection to mobile utilities support equipment (MUSE) units, which will allow repairs and maintenance on the prime movers needed to bring them back into operational condition.
SSC Pacific completed the short-circuit studies and dynamic analysis of protective relay settings for full power of both transmitter and de-icing operations to ensure safety of personnel and equipment.
In November 2013, a prototype solid-state crowbar, a high-voltage circuitry that enables FSBS strategic communications transmit sites to connect to the commercial power grid, was successfully installed in all four power amplifiers at Naval Computer and Telecommunications Area Master Station Atlantic Detachment Cutler (NCTAMSLANT DET Cutler). Temporary MUSE generators, which will provide backup transmitter power, were successfully tested with the crowbars to ensure no issues would occur with the MUSE units.
The Way Ahead
Phillips believes his innovation demonstrates the Navy’s recognition of the importance of the research and development accomplished at SSC Pacific.
“In being able to use NISE (Naval Innovative Science and Engineering Technology) Transition funding,” he said, “I was able to maximize a return on investment and solve a problem that had been plaguing the Navy for more than 20 years. The goal of my research is to provide the warfighter with improved capability, remove hazardous material from operational sites, and provide a significant cost savings by applying methods proven in cost-results-driven industry.”
The production version of the solid-state crowbar will be installed in the four power amplifiers at NCTAMSLANT DET Cutler, and the prototypes removed. The prototype versions will then be upgraded to the production model and sent to one of the other sites with the most compelling need for installation of the devices.
In addition to this effort, a site-specific version of the production solid-state crowbar will be produced for one of the VLF sites that operates at a higher voltage than any of the other sites. As the solid state crowbar was designed in a modular fashion, the effort will be primarily adding additional modules to withstand the higher voltage and reprogramming the controls to operate in this higher voltage environment.
This effort will then allow the upgrade or replacement of the diesel generators that provide backup power and substation equipment that supports the commercially supplied power at Naval Radio Station (Transmitter) Jim Creek. The solid state crowbar will allow for smaller generators and substation as this equipment will not be required to withstand the high transient forces associated with the ignitron crowbar circuit. A substantial cost savings will be obtained with the lower transient requirements of the new equipment.