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 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.