Summary of Fuse Testing for Barrel Module Fuse Boxes Duke University Jack Fowler Fuse Box Production Summary • Fuse Boxes have been in production for ~ 12 months • 35 sets of each type are being produced • This involves > 7500 fuses • Fuses were delivered from Oct 03 until Aug 04 Fuse Box Production Steps • Assemble Fuse Box components and solder • Test Fuse Resistance • Clean Fuse boxes and dry • Test Fuse Resistance • Dry fuse boxes for minimum 3 hrs at < 55° C • Conformal coat fuse box components • Final Test Boxes - continuity at < 100 V and check for breakdown at 2 kV • Final assembly – add hardware and heat shrink and label cables Fuse Boxes Post Production Tests • Once fuse boxes are through the final test, we perform simple resistance test on each of the fuses. • In the period of time between tests, the fuse boxes are stored on a shelf in the lab. Failed Resistance Test Post Production Fuse Recovery • The recovery was performed by applying ~ 600 V through a 6 MΩ resistor to all of the fuses. This applied ~ 100 µA current. This was applied for 1 minute. • The fuse resistance was tested and the results recorded. Fuse Recovery Fuse Conditioning after Recovery • After recovery, all of the fuse boxes were connected in parallel and a 100 µA current was applied. • The fuse boxes were left in this condition. • After 2 weeks, half of the boxes were removed and the fuse resistance was tested. This included ~3500 fuses. Fuse Box Conditioning Fuse Box Connections Fuse Tests after Two weeks of Conditioning Summary • Before recovery and conditioning, fuse failures seemed to be stabilizing at ~ 0.1 % per week. • Recovery was successful for 60 % of previously failed fuses. • After 2 weeks of conditioning, 33 % of “recovered” fuses failed. • During 2 weeks of conditioning, an additional 8 fuses failed. This equates to ~ 0.1%/week. • An additional 3 of the “recovered” fuses failed 1 week later bringing the failure rate to 40 %. No new fuses failed. Future Plans • Continue conditioning for the remaining half of the fuse boxes for 2 more weeks. • Continue testing post conditioned fuses weekly for additional failures. • Continue new design of fuse box without fuses. Resistors will take the place of the fuses.