Transcript HQ_LQ_coil_issues_FNALx

Coil parts & Instrumentation issues
for LQ/HQ coils tested at Fermilab
HQ/LHQ coil parts task force
Introduction
• Collect all issues related to HQ/LQ coil parts and instrumentation
found at Fermilab before, during or after the test
• Issues found before the test to be verified with the Lab fabricated
or instrumented the coil
• Keep updating the information on issues for old or forthcoming
tests
• Start summarizing findings
LQ/HQ coils tested at Fermilab
• LQS01a
– Strip heater damage, delamination on the inner coil surface
• LQS01b
– Strip heater damage
• LQS02
– Mixed up voltage tap wiring
• HQM01 (coil 12)
– Coil to IL pole piece short
• HQM02 (coil 13)
– Coil to IL pole piece short
– OL heater to coil short
• HQM03 (coil 14) in preparation to electrical checkout
– Coil to OL splice block short
– Wires not potted into the LE outer layer splice block
LQS01a
• Strip heater in coil 7 (PH07A01) was lost during the test
– Heater was connected in parallel with other heaters, HFU decay profile
slightly changed but was not noticed during the test
– Monitoring of HFU discharge was implemented after this test
• PH07A01 heater was repaired after the test
– Exposed area was filled with Stycast and 5-mil Kapton on top of it and
cured with pressure. Damaged area of the heater was replaced with a
10-cm long copper wire
– The same heater was lost again in LQS01b
LQS01a
• Delamination of coils inner diameter
– Large “bubbles” underneath the large sections of the heaters
• Rod SG are vulnerable to cool down
– Sector D rod SG was lost during the initial cool-down
– Additional sensor on each rod could help
HQM02 coil parts & instrumentation issues
Pre-test electrical check-out: short found between the coil and
the IL LE pole piece
- Short location in A10B10 segment, close to B10
- Inner and outer layer pole pieces at LE are in contact
- Small axial gap between the LE and RE pole pieces
Inner layer
Outer layer
HQM02 coil parts & instrumentation issues
Both strip heaters on the outer layer developed short to coil after
3rd quench at 4.6 K
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Significant increase of the quench current from ~14 kA to ~15.7
kA
Strip heaters isolated and removed from the magnet protection
Was is safe to continue testing ?
 Symmetric grounding of both the magnet and strip heaters, as
well as 10 mOhm dump resistor should reduce the maximum
voltage drop across the coil
 Several manual trips and heater provoked quenches performed
to analyze noise in signals
 Strain gauge data, especially from the bullets, were investigated
 Quench current was gradually increased up to 14 kA before
quench training was continued
HQM02 coil parts & instrumentation issues
When exactly the short developed ?
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Active ground fault protection system tripped only after the
quench
HFU discharge plot for quench #3 indicated that short
developed after the quench was detected (t=0)
OL heaters
IL heaters
HQM02 coil parts & instrumentation issues
When exactly the short developed ?
 HFU discharge profile compared to a reference plot
Quench # 2
Quench # 3
HQM02 coil parts & instrumentation issues
When exactly the short developed ?
 Ground fault current in quenches #3 and #18, both at ~ 15.7 kA
Quench # 3
Quench # 18
HQM02 coil parts & instrumentation issues
OL RE
HQM02 coil parts & instrumentation issues
2-mil Kapton ground wrap
3 layers of 5-mil Kapton insulation
HQM02 coil parts & instrumentation issues
11/30/2011
HQM02 inspection results
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OL RE spacer-to-end shoe (IL or OL):
OL RE spacer-to-IL RE spacer:
IL RE end shoe-to-OL RE end shoe:
OL RE spacer-to-OL coil:
OL RE spacer-to-IL coil:
OL RE spacer-to-strip heater (NT):
OL RE spacer-to-strip heater (T):
open
open
open
48.99 Ohm
49.12 Ohm
54.8 Ohm
3.37 Ohm
Heater to coil short developed during the quench
Did the spacer-to-coil short develop after the heater failure ?
HQ02
HQ13
22.6 mm
10.6 mm
26.8 mm
18.8 mm
HQ04
HQ14
HQM02 coil parts & instrumentation issues
OL LE before the test
OL LE after the test
HQM03 coil parts & instrumentation issues
Preliminary electrical check-out: short found between the coil
and the OL LE splice block
- Short is located close to B2, could be B2 voltage tap wire
pinched between the splice block
Short location
B2 vtap wire
HQM03 coil parts & instrumentation issues
Different technology of splice wiring is used at Fermilab
SS foil in Kapton
HQM03 coil parts & instrumentation issues
• Wires not potted into the LE OL splice block
• Need to repair (Stycast ?)