The Department of Defense, specifically the Navy, is seeking proposals for the development of a Transient Voltage Suppressor (TVS) aimed at enhancing the reliability of avionics in the F/A-18 E/F and EA-18G aircraft. The objective is to design a TVS that limits overvoltages to a maximum of 150 volts root-mean-square (Vrms), which is crucial for meeting the MIL-STD-704E electrical power interface specifications, as many avionics components currently fail due to inadequate testing against the required 180 Vrms. This initiative is significant for both military and commercial applications, as it addresses the need for avionics to withstand overvoltage transients, thereby improving overall system reliability. The solicitation is currently closed, with the application due date having been set for June 12, 2024, and further details can be found at the provided source link: https://www.dodsbirsttr.mil/topics-app/.

## Description

F/A-18 E/F and EA-18G use MIL-STD-704E Aircraft Electric Power Characteristics, the electrical power interface specification. MIL-STD-704E requires avionics to withstand overvoltage transients to 180 Vrms, but many avionics components were not tested to the 180 Vrms causing reduced avionics reliability.MIL-STD-704E requires avionics to withstand overvoltage transients to 180 Vrms, but many Avionics were not tested to the 180 Vrms transients, and are failing in the fleet as a result. The reason testing was not performed for F/A-18 was because in 1999 when aircraft went into full-rate production, there was no test method for MIL-STD-704E; the test method was not implemented until 2010. The most economical solution per aircraft is to place the TVS on two electrical busses instead of inside 50 avionic boxes. The TVS needs to limit the overvoltages to 150 Vrms maximum instead of the MIL-STD-704E of 180 Vrms requirement. The TVS needs to start limiting when the voltage gets to between 130&ndash;140 Vrms, and clamp at a maximum of 150 Vrms.

## Objective

Develop a Transient Voltage Suppressor (TVS) that will limit the overvoltages to avionics components to 150 volts root-mean-square (Vrms) maximum, instead of the MIL-STD-704E requirement of 180 Vrms.

## Phase I

Perform a study to design a TVS that meets F/A 18- E/F and EA-18G capabilities. Use MIL-STD-704E Aircraft Electric Power Characteristics, the electrical power interface specification, as a basis for the design. The Phase I effort will include prototype plans to be developed under Phase II. The TVS needs to limit the overvoltages to a maximum of 150 Vrms instead of the MIL-STD-704E of 180 Vrms requirement. The TVS needs to start limiting when the voltage gets to between 130–140 Vrms, and clamp at a maximum of 150 Vrms.

## Phase II

Development of two TVS prototypes that should meet the following test requirements:<ol><li> Joule dissipation at 25 &deg;C &lt; 2625 Joules,</li><li> Joule dissipation on infinite heatsink at TL = 75 &deg;C &lt; 2625 Joules,</li><li> Peak forward surge current, 1025ms single half-sinasoidal wave (bidirectional only) 350 amperes root mean square (Arms),</li><li> Operating and storage temperature range -55 &deg;C to +175 &deg;C,</li><li> Vrms minimum range 130 to maximum range 140,</li><li> Arms maximum reverse leakage 5 mA to 2 &micro;A at Voltage Reverse Working Maximum 108 Vrms,</li><li> Voltage Reverse Working Leakage of a Vrms 108,8. Maximum Reverse Surge Current I peak to peak Amps rms 172.9 Ipp, and9. Maximum Clamping Voltage 150 Vrms at Ipp.</li></ol>Navy Military Standards &amp; Testing:10. MIL STD 704 Electrical interface,11. MIL STD 810 needs to be environmentally qualified,12. MIL STD 461 EMI

## Phase III: Dual Use Applications

Perform laboratory testing and then install the prototype(s) in an aircraft for an aircraft ground and flight test.Commercial electrical system developers that use the electrical power interface specification can use TVS. Commercial aircraft requires avionics to withstand overvoltage transients to 180 Vrms, but many avionics components were not tested to the 180 Vrms.

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