1. MQXF PD and Break Down Test Campaign
Jan Petrik TE-MSC LMF
With thanks to: Pierre-Antoine Contant, Paolo Ferracin
20/03/2019

2. Partial discharge
Occurs when high enough excitation voltage(for given insulation system) is present
Represents miniature failures in insulation (bubbles, voids, discharges..)
Can accumulate over time and result in failure
Requirement for PD free insulation in power transformers and other expensive equipment which are subjected continuous AC excitation – not our case
Very sensitive
Good for relative comparison
Jan Petrik, 20/03/2019 2

3. Partial Discharge AC
Filter PD
Detector
DUT
Jan Petrik, 11/01/2019

4. What we evaluated PD inception voltage PD vs voltage PD pattern Tricky
Comparison based
Jan Petrik, 20/03/2019 4

5. Limits We do not have bare coil Where are the limits of used cables?
QH contains Voltage taps traces
Cables
We measure everything together
Where are the limits of used cables?
Quick test with separate cable V
Single test, let’s assume that above 1300V we are not sure…
Distinctive PD pattern
If PD activity was low, we’ve kept increasing test voltage, in 3 cases the coil DP pattern was swamped by cables
Jan Petrik, 20/03/2019

6. Sample size 33 QH 9 coils MQXFS3: 105, 106, 107, LARP 8
207 – virgin coil
Jan Petrik, 20/03/2019

7. PD Inception Voltage - [ACV]
Overall Results
Assembly
Coil
Side
Field
PD Inception Voltage - [ACV]
MQXFS3
LARP 8
Right
High
559
Virgin
207
Low
1000
MQXFS5
206
619
Left
1011
204
821
205
1022
106
837
107
1053
850
105
1055
853
203
1069
902
1072
922
1086
929
1096
960
1136
961
1139
976
1150
980
1218
986
1234
992
1238
1342
1349
107 Right-High – QH already shorted
Jan Petrik, 20/03/2019

8. PD Inception Voltage - [ACV]
Results Per Coil
PD Inception Voltage - [ACV]
Coil
QH Count
Avg
Min
Max
STD
Larp 8 4
559
1349
206 3
619
1000
204
937
821
986
106
837
1150
207
928.5
850
1011
107
1017
902
1096
205
1099
922
1234
203
1027.5
929
1136
105
992
1342
Due to RH QH
Virgin Coil
Jan Petrik, 20/03/2019

9. PD Inception Voltage - [ACV] PD Inception Voltage - [ACV]
Results per QH
PD Inception Voltage - [ACV] QH
QH Count
Avg
Min
Max
STD
All QH 33
559
1349
High Field only 16
1342
Low Field Only 17
961
Left Side only
853
Right side only
1218
Left & High only 8
1046.5
Left & Low only
980
Right & High only
992
Right & Low only 9
And per Assembly
PD Inception Voltage - [ACV]
Assembly
QH Count
Avg
Min
Max
STD
MQXFS3 14
559
1349
MQXFS5 15
619
1234
Jan Petrik, 20/03/2019

10. PD Results The Worst 10 – all are High field QH
7 out of 10 – Right side, High field QH
Right side, high field is the worst QH for 8 out of 9 coils…#107 – RH QH was already busted…
Virgin coil (#207) is comparable with others
This would indicate (= not conclusive!!) that there is no damage during assembly and cold testing
To be sure we would need to measure #207 after cold testing.
Pattern analysis – yet to be done
Jan Petrik, 20/03/2019 10

11. Breakdown Tests Tests 5 coils 20QHs – 3 already damaged
Break down test – ramp 1kV/min
Burn mode – Step, 500V increase
Capacitive discharge to do more damage
5 coils
105, 106, 107, LARP 8, 206
20QHs – 3 already damaged
Jan Petrik, 20/03/2019 11

12. Splice issue Issue in insulation of cable splice
Effect of cold testing
Coil #105 and #106
Might have influenced PD measurements
PD inception voltage quite away from breakdown – all but #105LH
Assembly
Coil
Side
Field
PD Inception Voltage - [ACV]
Inception Voltage – Peak [V]
Ramp Test Breakdown [DCV]
MQXFS3
105
Left
High
1342
1961
Low
1086
4850
Right
992
4521
1055
2223
106
1072
5567
1150
2297
837
2137
Jan Petrik, 20/03/2019 12

13. PD Inception Voltage - [ACV]
Breakdown results
Coil
Side
Field
PD Inception Voltage - [ACV]
IR [GΩ] 25V/30s
Ramp
Burn Test Passed
105
Left
High
1342
>33.8
1961
10kV
Low
1086
4850
Right
992
4521
6kV
1055
2223
106
1072
5567
1150
>34
2297
837
2137
8kV
107
1053
8720
902
>10kV
1096
7201
7.5kV
206
960
1803
2kV
1000
N/A
619
5287
LARP 8
1238
1349
6878
559
9.2
737
1139
Jan Petrik, 20/03/2019

14. Breakdown - Preliminary Results
20QH – 3 already damaged – 17 QH to be tested
9 (10) reached 10kV with no BD (Burn test)
5 better than 5kV
2 very weak
2 shorts through neighbouring QH !!
Fast ramp(burn mode) gives better results than 1kV/min ramp
Jan Petrik, 20/03/2019 14

15. Suggestions Better routing of signals Distances on QH (QH/QH,QH/VT)
Cable bundles – Different bundles ?
Cable reliefs are missing
Measurement suggestions
Bare QH
#207 After cold testing
Coverlay for QH trace – reduce possibility of surface discharge in case of delamination/resin cracks
Jan Petrik, 20/03/2019 15

16. Extra Slides
Jan Petrik, 20/03/2019 16

17. Jan Petrik, 20/03/2019

18. MQXFS5 Coil 203, 204, 205, 206 3 thermal cycles ~50 quenches
Paolo Ferracin

19. MQXFS3 Coil 105, 105, 107 Coil 8 5 thermal cycles 1 full disassembly
~100 quenches
Coil 8
2 thermal cycles
~50 quenches
Paolo Ferracin