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 Fuses Clean Fuse boxes and dry Test Fuses 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.

Type 1 Fuse Failure Rates Nov 17 – 33 / 1518 or (2.17 %) Nov 23 – 7 / 1485 or (0.47 %) Nov 28 – 6 / 1478 or (0.41 %) Dec 7 – 1 / 1472 or (0.07 %) Cumulative Totals 47 / 1518 or (3.10 %)

Type 2 Fuse Failure Rates Nov 17 – 49 / 2346 or (2.09 %) Nov 23 – 4 / 2297 or (0.17 %) Nov 28 – 4 / 2293 or (0.17 %) Dec 7 – 6 / 2289 or (0.26 %) Cumulative Totals 63 / 2346 or (2.69 %)

Type 3 Fuse Failure Rates Nov 17 – 14 / 1872 or (0.75 %) Nov 23 – 5 / 1858 or (0.27 %) Nov 28 – 1 / 1853 or (0.05 %) 5 / 884 or (0.57 %)* Total 6 /2737 or (0.22 %) Dec 7 – 3 / 1852 or (0.16 %) 3 / 879 or (0.34 %)* Total 6 / 2731 or (0.22 %) Cumulative total 31 / 2756 or (1.12 %) * New type 3 boxes were added to the tests

Total Fuse Failure Rates

Cumulative Test Results Total Cumulative of all fused tested –Nov 17 ’04 – 97 / 5736 or (1.69 %) –Nov 23 ’04 – 112 / 5736 or (1.95 %) –Nov 28 ’04 – 128 / 6620 or (1.93 %)* –Dec 7 “04 – 141 / 6620 or (2.13 %)* 141 fuses corresponds to 1128 straws * New type 3 boxes were added to the tests

Comments and Summary The failure rates from the Nov 17 test were higher because time between tests varied up to 6 weeks. The remaining tests have been done at ~ 1 week intervals. Many fuses were replaced during the production process. These were not documented well as they were attributed to handling of the boxes during the process without the fuses being potted. Approximately 6 of the fuses that failed the test were found to be good in the next test. These remain marked as failed and will be monitored. The tests will continue into next year to determine if these are infant mortalities or if the failure rate remains constant. If the rate drops and begins to appear more acceptable, then tests with HV applied will be performed to see if it has any effect.

Future task??? Begin to redesign the fuse box without the use of fuses. IF the HV connection boxes are to be made, this will take a minimum of 4 months.