cscm type test: diode leads and diodes gerard willering & vincent roger te-msc with thanks to...
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CSCM type test:Diode Leads and Diodes
Gerard Willering & Vincent RogerTE-MSC
With thanks to Bernhard Auchmann, Zinour Charifoulline, Scott Rowan, Arjan Verweij, Daniel Wollmann
and all involved in the CSCM test.
12-06-2013 - MPE-TM
Outline
• Diode leads• Test parameters and conditions• Measurements• Comparison with test station data
• Diodes• Test parameters and conditions• Measurements
• Concluding remarks
Gerard Willering – TE-MSC-TF - CSCM type test - 16/05/2013
Gerard Willering – TE-MSC-TF - CSCM type test - 16/05/2013
Diode leads: Measured voltages
Board A
Board B
Large data set acquired:RB 156 voltage signalsRQF 51 voltage signals
QPS Board A: BB + interconnectionsQPS Board B: BB + interconnections + diode leads
Diode lead resistance
Gerard Willering – TE-MSC-TF - CSCM type test - 16/05/2013
Diode leads
Include 3 types of contact- Diode – Heatsink (clamped)- Heatsink – busbar (bolted)- Busbar – busbar (bolted)- About 60 cm of bus bar
In total 6 contacts per voltage signal.
Diode lead resistance
Gerard Willering – TE-MSC-TF - CSCM type test - 16/05/2013
Low-resistance RB lead
-20
0
20
40
60
80
100
0 5 10 15 20 25 30 35 40
Resi
stan
ce (u
Ohm
)
Time (s)
DCBD.7R2.L 2 kA4 kA4 kA6 kA7 kA8 kA7 kA9 kA6 kAI-profile
Diode lead resistance
Gerard Willering – TE-MSC-TF - CSCM type test - 16/05/2013
Highest resistance RB lead- At 2 kA run still low resistance- Resistance increase from the first 4 kA run onwards- Resistance reduction during long 7 kA run after short 8 kA run.
- Low-current characteristics used for statistical analysis.
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200 250 300
Resi
stan
ce (u
Ohm
)
Consecutive runs (time in seconds)
DCBA.A16R2.R 2 kA
4 kA
4 kA
6 kA
7 kA
8 kA
7 kA
9 kA
6 kA
low current resistance
2 kA4 kA
4 kA
6 kA 7 kA
8 kA 9 kA 6 kA
7 kA
Typical behavior: 1. At the first ramp to a higher current
the resistance increase is significant
2. After a prolonged run at the similar current the resistance is reduced.
For the RQF diode leads similar behavior is seen.
-20
-10
0
10
20
30
40
50
2 kA 4 kA 4 kA 6 kA 7 kA 8 kA 7 kA 9 kA first to last run
Resi
stan
ce (u
Ohm
)
Run
Low current resistance affected by each runRB
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200 250 300
Resis
tanc
e (u
Ohm
)
Consecutive runs (time in seconds)
DCBA.A16R2.R 2 kA
4 kA
4 kA
6 kA
7 kA
8 kA
7 kA
9 kA
6 kA
low current resistance
2 kA4 kA
4 kA
6 kA 7 kA
8 kA 9 kA 6 kA
7 kA
During CSCMRmax = 70 µΩ in 6 contacts combined
In Block-4Rmax > 35 µΩ in 1 diode-heatsink contact.
0
5
10
15
20
25
30
35
40
0 200 400 600 800 1000 1200
Resi
stan
ce (μ
Ω)
Time of consecutive runs (time in ms)
Test station measurement Block4 - MDA 0790 - Heatsink to diode resistance
1.3 kA
5 kA 10 kA
13 kA 13 kA
8 more runs at13 kA
100 mV DAQ saturation:35 microOhm is reached at least!
Note: - Different current profiles- Different cooling
Diode lead resistance - Comparison to test station data
?
Fast jumps in diode lead resistanceFast jumps identified as the main risk: possibly mechanical movement in bolted joints
Where Type I (kA)
Step (mv)
Step (μΩ)
Time (ms)
LHC ’11 Quad lead 4 160 40 <50
LHC ‘13 Dip lead 4 30 7 < 120
LHC ’13 Quad lead 4 50 12 < 120
LHC ’13 Quad Lead 6 50 8 < 120
LHC ‘13 Quad lead 6 24+18 4+3 < 120
SM18 HS-diode 13 65 5 50
0
2000
4000
6000
8000
10000
12000
14000
0
5
10
15
20
25
30
0 10 20 30 40 50 60
Curr
ent (
A)
Resi
stan
ce (μ
Ω)
Time (s)
1st test at 13kA
2nd test at 13kA
3rd test at 13kA
4th test at 13kA
5th test at 13kA
6th test at 13kA
7th test at 13kA
8th test at 13kA
9th test at 13kA
10th test at 13kA
Current
2011 – LHC quad - Verweij
2013 – CSCM type test
2012 – SM18 test station Heatsink-busbar
The SM18 test shows that heatsink-busbar contacts can have fast jumps.
Remarks on Diode lead resistance
Gerard Willering – TE-MSC-TF - CSCM type test - 16/05/2013
Data analysis- Maximum resistance is in the range as observed for diode-heatsink contact- Fast jumps may occur as well in diode-heatsink contact- A resistance increase in the other two contacts are not identified, but cannot
be excluded.- The high-resistances are all “self-healing” as was seen before for diode-
heatsink contacts
Impact on the test after LS1- No unexpected results → No show stoppers.
Note: the part that was deemed most risky is consolidated during LS1 (the connection plates of the quad diode leads).
Diode opening
Gerard Willering – TE-MSC-TF - CSCM type test - 16/05/2013
Prior to high current runs the diodes need to be opened.
1. PC initialization
2. Ramp to 400 A
3. Warmup of magnets and gradual opening of diodes
4. Warmup of diodes → reduction of Vforward
5. High current ramp
In stage 1 and 2 most current is in the magnetFrom stage 3 on the current shifts more to the diode circuit.
“Slow” opening is required to allow the PC to respond.
Diode opening – Forward voltage
Gerard Willering – TE-MSC-TF - CSCM type test - 16/05/2013
0
0.5
1
1.5
2
2.5
3
0 20 40 60 80 100 120 140 160 180 200
Volta
ge (V
)
Time (s)
DQQDS.B10L3.RQF.A23 Run 1 - 900A
Run 2 - 2kA
Run 3 - 4kA
Run 4 - 6kA
Run 5 - 6kA
run 6a - 400A
Run 6b - 8kA
0
0.5
1
1.5
2
2.5
3
0 20 40 60 80 100 120 140 160 180 200
Volta
ge (V
)
Time (s)
DQQDS.B11L3.RQF.A23 Run 1 - 900A
Run 2 - 2kA
Run 3 - 4kA
Run 4 - 6kA
Run 5 - 6kA
run 6a - 400A
Run 6b - 8kAvariation less than 10 mV
Dip in voltage just after opening
Typical opening1. Increase in Imagnet and V
2. Vforward reached
3. Warming of the diode – decrease in Vforward
1
2
3
Dip in voltage after opening- Only in Quad diodes at I = 400 A in 47 out
of 364 cases.- Quick decrease in voltage suggest quick
increase in temperature → local warm-spot- Regular pattern, always 1.55 to 1.65 V- At 1.5 V the temperature is well below 70 K.
- In all the cases the voltage characteristics is the same within ± 1 % and the dip seems to have no permanent effect.
Remarks on Vforward of the diodes
Gerard Willering – TE-MSC-TF - CSCM type test - 16/05/2013
Data analysis- Strange dip seen only in 13 % of Quad diode openings- At high currents these diodes did not show any deviation from normal behavior.
Comments for LS1 qualification test- Since Vforward remains at 1.6 V the temperature is much less than 70 K. - After the dip all diodes show similar values of Vforward .
Concluding remarks on diodes and diode leads
Gerard Willering – TE-MSC-TF - CSCM type test - 16/05/2013
- No show stoppers identified on diodes and diode leads for the CSCM test in LS1
- Large sets of data on diode leads show resistance variations in the range that has been seen before.
- Variations in diode opening voltage were unexpected, but are deemed not to be a risk for the test.
Spare slides
0
10
20
30
40
50
60
70
80
90
2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4
Num
ber o
f eve
nts
Maximum voltage during opening (V)
With dip in voltage
Without dip in voltage
RQF - total events 364 (7 runs with 52 diodes)
Diode opening – statistics of dips
With a lower opening temperature (higher voltage) the dip is occurring more often.
0
5
10
15
20
25
0 500 1000 1500 2000 2500
Res
ista
nce
(u
Oh
m)
and
Cu
rren
t (k
A)
Time (s)
Diode-heatsink MDA1267-A
Increasing to 6 kA Increasing in to 13 kA
-10
-5
0
5
10
15
20
25
30
35
40
2 kA 4 kA 6 kA 6 kA first to last run
Resi
stan
ce (u
Ohm
)
Run
change in low current affected by each runRQF
-20
-10
0
10
20
30
40
50
2 kA 4 kA 4 kA 6 kA 7 kA 8 kA 7 kA 9 kA first to last run
Resi
stan
ce (u
Ohm
)
Run
Low current resistance affected by each runRB