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
100
13 13 136 6 4
9
164
0
20
40
60
80
100
120
140
160
180
17-Nov-04 23-Nov-04 28-Nov-04 7-Dec-04 16-Dec-04 22-Dec-04 30-Dec-04 6-J an-05 Total FuseTests
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
100
13 13 136 6 4
9
164
43
11 12 95 6 4
9
99
0
20
40
60
80
100
120
140
160
180
17-Nov-04 23-Nov-04 28-Nov-04 7-Dec-04 16-Dec-04 22-Dec-04 30-Dec-04 6-J an-05 Total FuseTests
Failed Resistance Test Post Production
Recovered 12-Jan-05
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
19
63
6
2 3 3 4
42
8
1 1 1 02 1 0
14
1 1 0 1 0 0 0 03
8
0
5
10
15
20
25
30
35
40
45
17-Nov-04 23-Nov-04 28-Nov-04 7-Dec-04 16-Dec-04 22-Dec-04 30-Dec-04 6-J an-05 Total FuseTests
# of Recovered Fuses tested after two week trainingRecovered Fuses failed after two week training 1-Feb-05Recovered Fuses failed after two week training 6-Feb-05**Additional Fuses Failed during two week 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.