D. Bozzini, AT/MEL/EM, Chamonix Workshop XIV, January 2005 1 Chamonix Workshop XIV Session 4 –...
-
Upload
aubrey-stewart -
Category
Documents
-
view
217 -
download
0
Transcript of D. Bozzini, AT/MEL/EM, Chamonix Workshop XIV, January 2005 1 Chamonix Workshop XIV Session 4 –...
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
1
Chamonix Workshop XIVSession 4 – Other Issues affecting Beam Commissioning 1
Electrical Quality Assurance (ELQA)
Tuesday, 18th January 2005
Davide Bozzini, AT-MEL-EM
Thanks to S. Russeschuck, F.Rodriguez Mateos, T. Zichler & the HCWG members
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
2
Introduction to the LHC Electrical Quality Assurance (ELQA)
The ELQA activities and LHC operation with beam
Detection of electrical faults
Classification of electrical faults
Diagnostic methods for detection
Examples of electrical faults diagnostic
Acceptance and qualification criteria
Accessibility to the electrical circuits
Sequence and duration of diagnostic activities
Staff experience and familiarity with the LHC machine, resources
The experience of String 2
Conclusion
Outline
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
3
The ELQA activities
A series of actions to ensure the correct functioning of the electrical circuits of the LHC machine
Definition
Define a quality assurance plan to apply to the machine during installation, hardware commissioning and operation
Provide the procedures, tools and resources to perform the necessary checks and tests during ELQA activities
Grant the traceability of checks and tests performed at the different stages
Aim
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
4
The ELQA activities
When
Manufacturing of componentsDFBX, Line N cable,…
Machineassembly
- diagnostic- re-qualification
- Continuity- Polarity- Electrical insulation- Global resistance, inductance- Global insulation- ... ...
- Insulation prior/during/after cool-down - Transfer function- ... ...
Time
Hardwarecommissioning
Operation, Shutdown, repair
- Continuity- Polarity- Electrical insulation
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
5
The ELQA plan
Qualification and preparation before introduction into the tunnel- Surface (cold) tests
- generation of non conformity lists- qualification of individual electrical component
DFBDFBXDFBMDFBA
current leads13 KA7.5 KA600 A60 A
120 A
magnetsdipolesarc sssIR sss
separation dipolesinner triplet
bus bars6 KA
600 A (line N cable)
Specification ofComponents
(Electricalparameters)
EStype of circuitsinstrumentation
Electrical conformityreport
ELQA activities during sub-sector assemblySpecification for
electricalinterconnections
M1 & M2Line N BBinner triplet
Electricalinterconnection
Layouts
ELQA activities of sub-sector circuitsduring hardware commissioning
Traceability ofELQA
documentationgenerated during
assembly andcommissioning
Technicalsupport
- Tools forassembly
-Tools forelectrical
verifications- Tools fordiagnostic
Beam commissioning&
Operation
Tunnel environment
LHC Referencedatabase
Existingelectrical
non-conformities
Generatedelectrical
non-conformities
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
6
ELQA and LHC operation with beam
Though considered unlikely, it’s almost sure that due to the complexity of the LHC machine we will face faults and problems related to the superconducting (SC) electrical circuits during the operation with the beam
A fault affecting a SC electrical circuit can be unpredictably provoked by different sources and, in most cases, it cannot be detected on-line or anticipated
Most of the electrical faults will have a direct impact on the machine availability and/or on the beam quality
Beam Based measurements may require in-situ verification of the magnets polarities (Chamonix X, J-P Koutchouck, Finding a faulty element of the machine)
Motivation
Therefore Efficient postmortem ELQA diagnostic methods to be applied during commissioning and
operation with beam must be established
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
7
Detection of electrical faults
The beam (1)
– Via the BPM’s and after investigation
The power converters (2)
– Over voltage
– Detection of an earth fault
– Monitoring of leakage current
The quench protection system (3)
– Loss of instrumentation (Voltage taps)
– Detection of an open circuit
– Consecutive quenches in a given half/cell
During the ELQA activities (4)
– Measured electrical characteristics after a shut down period or re-commissioning out of specified parameters
Except for (1), practical experience acquired during hardware commissioning will be available
Sources for electrical faults detection
Events that may launch an ELQA
diagnostic intervention
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
8
Classification of the electrical faults (some examples)
Fault Consequence Detection Diagnostic method
Inverted polarity of a magnet within a series (ex: MCS)
Beam quality- BPM’s- Beam observations
- Polarity check
Open circuit of a main circuit
Beam abort- QPS- Power converter
- Continuity check- Transfer function
Short to ground of a main circuit
Beam abort - Power converter- High voltage test- Transfer function
Loss of instrumentation used for magnet protection
Beam abort - QPS- Continuity check- TDR
…………….. ………………. …………………… …………………
The notorious one’s
The malicious one’sFault Consequence Detection Diagnostic method
Quench of bus bar segments or splices
Beam abort - QPS ?
Transitory shorts to ground or between circuits
Beam abort - Power converters ?
High ohmic resistance of bus bar interconnect
?- QPS- Cryo system
…………………
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
9
Diagnostic tests (1)
Diagnostic test Applied to Method
Electrical insulationsegment - ground DCV supply
segment - segment I leakage
Capacity Circuit - groundDCV
Measurement of C
Continuitysegments DCA supply
Circuit Closed loop
Polaritysegments DCA supply
Circuit Voltage drop via V_taps
Instrumentation Current lead V_tapsDCA supply
Voltage drop via V_taps
Diode polarity MB,MQ diodesACV supply
Turn on voltage
Transfer functionCircuit Z(f)
Circuit - ground Z(f)
For the notorious faults
Wide experience acquired during machine assembly and hardware commissioning
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
10
Diagnostic tests (2)
For the malicious faults
All tests of the previous slide are applicable but probably not enough
Several ideas on the air, some of them already tested
– Time domain Reflectometry + high voltage pulse
– High voltage partial discharge
– Specific hardware to be locally and temporarily installed during operation in order to get detailed information about transitory faults
– Power dissipation measurements to localize ohmic resistances (require collaboration with cryogenic specialists)
– ……………………..
A systematic approach will be difficult to be applied
Experience will only be acquired on field when such faults will arise
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
11
Electrical fault diagnostic (1)
Ga
in/
rea
l
Ph
ase
/ im
ag
Frequency [Hz]
Ga
in/
rea
l
Ph
ase
/ im
ag
Frequency [Hz]
Transfer function of MQD and MQF string circuits at cold (1.8 K)
– RQF (reference)
– RQD phase(1Hz)= 0º !!
– RQD Z(1Hz)= 6309 ohm
– RQD has a high resistance somewhere, NOT OK
Transfer function of a portion of circuit via the local voltage pick-up instrumentation
– Coils of two MQs (blue and green), OK
– Portion of circuit including three dipoles (red), NOT OK
Transfer function Z(f)
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
12
Electrical fault diagnostic (2)
Progressive powering (without beam) of the SC circuit
Follow-up of temperature trend through the string of magnets
Calculation of the dissipated power by joule effect
Localization of an increase of temperature
Detection of a high ohmic resistance in a MQF circuit
RQF Power dissipation test @ 1.8 K
0.0E+00
5.0E-01
1.0E+00
1.5E+00
2.0E+00
2.5E+00
3.0E+00
27/0
6/20
0310
:00:
00
27/0
6/20
0310
:01:
40
27/0
6/20
0310
:03:
20
27/0
6/20
0310
:05:
00
27/0
6/20
0310
:06:
40
27/0
6/20
0310
:08:
20
27/0
6/20
0310
:10:
00
27/0
6/20
0310
:11:
40
27/0
6/20
0310
:13:
20
Time
Cur
rent
[kA]
,
U_d
iff [V
],
Res
ista
nce
[ohm
]
0.E+00
2.E+02
4.E+02
6.E+02
8.E+02
1.E+03
1.E+03
Pow
er d
issi
patio
n [W
]
Power dissipation
Current
U_diff
Resistance
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
13
Electrical fault diagnostic (3)
Allows to determine the quality of the electrical insulation
Is a qualitative analysis
Requires time and a high practical experience, good feeling and good luck
Partial discharge test of a PS dipole magnet
Courtesy T. Zickler
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
14
Electrical fault diagnostic (4)
Electrical insulation degradationDescription RB [Mohm]
Reference at warm before pump down of phase 3
(2003-03-28)10.1
Reference at cold before pump down of phase 3
(2003-04-28)9.4
Reference at cold after 13 kA circuit problems
8.7
Warm cables connected, cold masses under gaseous helium
10
After warm cable dismantling 14
After cold mass purge and injection of air
29.6
After MRB dismantling 30.8
Separation of Bus Bars in the MRB ext BB int BB
After short circuit dismantling and BB cleaning 31.6 725
After disconnection of RB Bus bars in
between SSS4 and MB4
MB4-to-MB6 13100 9150
DFB-to-SSS4 31.4 16800
Example of the MB circuit of String 2 phase 3
Resistance to ground out of specification but not a firm short to ground
Localization of fault only possible if the circuit can by split in sub circuits (opening of interconnections is needed)
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
15
Acceptance and qualification criteria
Current leakage of a main dipoles (MB) electrical circuit
The power converter will turn off if Ileak > 50 mA (LHC-D-ED-0001 rev 2.0)
By specification (LHC-M-ES-0001 rev 1.1) the maximum current leakage allowed for a MB circuit corresponds to the number of components that composes the circuit (434) times 20uA / component. This gives an Imax < 8.68 mA
Active leakage current detection level is 5 times higher that the maximum leakage accepted in the specification
The leakage may change depending on the machine/circuit conditions. It is essential to store all the measurements during the time to allow analysis and understanding of the variation
Need to define how to deal, in particular at the beginning of the machine operation with measured values between the two limits
Applicable to all 1715 SC circuits
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
16
Accessibility
PS machine “warm”. Electrical circuits are easily accessible and visible
For diagnostics almost all senses can be used: hearing , visual, smell, touch
Warm machine
LHC machine “cold” electrical circuits will not be directly accessible
This picture shows the String 2 phase 1, i.e. 54 meters without access to the circuits. Diagnostic has been a nice exercise. LHC machine will be 2700 m!
Diagnostic may require the local access to the circuit (opening of interconnections).
Cold machine
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
17
Sequence and duration of diagnostic activities
T0
Activity
Diagnostic phase #1
Analisys and decision
Diagnostic phase #2
Intervention repair
Re-qualification
T1 T2 T3 T4 T5 Time
Time for diagnostic phases #1 and #2 - fixed, if the fault is observable
- variable, if the fault is not observable
Time for analysis and decision - variable, and relies on decision makers
Time for intervention and repair - fixed, if the intervention is known
- variable, if the intervention is new
Time for re-qualification - fixed, procedures known from HC
T0
Activity
Diagnostic phase #1
Analisys and decision
Diagnostic phase #2
Intervention repair
Re-qualification
T1 T2 T3 T4 T5 TimeT6 T7
Opening of the machinefor local diagnostics
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
18
Staff experience and familiarity with the LHC machine, resources
Fundamental experience will be acquired during machine assembly and hardware commissioning
Beam commissioning starts in 2007 most of the knowledge will be gone
Success of ELQA activities during beam commissioning need experienced and well trained personnel
0
2
4
6
8
10
12
14
16
18
Q12005
Q22005
Q32005
Q42005
Q12006
Q22006
Q32006
Q42006
Q12007
Q22007
Q32007
Q42007
Time
Nr.
of
pe
rso
n
HNINP collaboration
FSU
Tech. Students
Staff
Assembly Hardware commissioning
Beam commissioningand operation Interventions during beam
commissioning and operation will have to deal with radiation
Staff shall be familiar not only with the ELQA procedures but also with safety rules and tunnel environment
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
19
The Experience of STRING 2
Reference documents
– From String 2 to the Hardware commissioning of the first sector: A challenge?, slides,F. Rodriguez Mateos, LHC days workshop 2003
– F. Rodriguez Mateos, String 2 Report, EDMS
Outcomes related to the ELQA activities
– Time for diagnostic and analysis was largely underestimated
– Several new methods for diagnostic where tested to determine the source of the faults. →some of them described in this speech
– Despite all the effort put into diagnostic and analysis we could not determine what was the fault in a bending dipole magnet
– The beam, the radiation and most of the tunnel environment constraints were not there
D.
Boz
zini
, A
T/M
EL/
EM
, C
ham
onix
Wor
ksho
p X
IV,
Janu
ary
2005
20
Conclusion
Assuming a successful hardware commissioning, day 1 of commissioning with beam might be successful, nevertheless we must be prepared for diagnostic interventions during the following days, weeks, months
Operation with beam will have an impact on ELQA activities. Access, safety, radiation rules shall be respected
The detection of faults will be done by different systems (PC, QPS, BPM’s,…). Exchange of information, collaboration is essential
Be ready for unpredictable faults requiring hard interventions (opening of interconnections)
Resources: Experience acquired during hardware commissioning is not granted for 2007 and later. A sufficient number of CERN staff specialists supported by the extension of the HNINP collaboration (motivated now by the need of personnel during beam commissioning and operation) shall be considered
On call service 24/24 and 7/7 seems to be necessary. Not foreseen at the moment
String 2 was an excellent exercise. A sector test with beam would be a must for optimization of ELQA diagnostic activities