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.