Transcript QPS electronics – quench heater circuits I

QPS system and its risks
 Principal risks
 General remarks
 Quench heater circuits
 Quench detection electronics
AT-MEL-PM, R. Denz, CERN, CH-1211 Geneva 23
 QPS controls
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QPS system and its risks – principal risks
 Electrical safety and the QPS system – principal risks
– Charging voltage and stored electrical energy of the quench heater
power supplies
• 6200 power supplies installed in LHC
AT-MEL-PM, R. Denz, CERN, CH-1211 Geneva 23
– Electrical potential of the superconducting circuits
• All quench detection systems galvanically connected to
superconducting circuits
 Don’t forget …
– All QPS electronics fed by 230 V AC UPS
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QPS system and its risks – general remarks
 All QPS electronics is protection class 1, low voltage B
– Housing conducting and connected to protective earth (PE)
– Operational voltages up to 1 kV DC
 All QPS electronics is protected against contact (according EN 60529)
AT-MEL-PM, R. Denz, CERN, CH-1211 Geneva 23
– IP20 (detectors) or IP30 (quench heater power supplies)
– No risk to touch live parts of the installations as long as you:
• are not E.T. …
• follow the rules
• don’t disconnect or cut the respective cables
• don’t open QPS electronics, distribution boxes, Instrumentation
Feed-through System (IFS) boxes while systems are powered
• don’t flood the QPS installations
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QPS electronics – quench heater circuits I
 Quench heater circuits
– Used within protection of MB, MQ,
insertion region magnets and inner triplets
– 900 V DC between poles, ±450 V DC to
earth (PE)
AT-MEL-PM, R. Denz, CERN, CH-1211 Geneva 23
– Note: a quench heater power supply
stores 2.9 kJ of electrical energy
Quench heater power supplies Q4.L8
– Once charged (i.e. QPS-IST @ cold is
finished) the quench heater power
supplies may discharge into the quench
heaters installed in the magnet cold mass
at any time
• Unless there is a specific request to
switch off all quench heater power
supplies stay charged (until they
break or the de-commissioning of
LHC …)
MB protection rack
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QPS electronics – quench heater circuits II
 Quench heater circuits - main magnets
(MB and MQ)
– Quench heater power supplies
DQHDS installed in the yellow
racks underneath the main dipoles
(also for MQ protection)
AT-MEL-PM, R. Denz, CERN, CH-1211 Geneva 23
• MB: 4 x DQHDS
MB IFS box connection
• MQ: 2 x DQHDS
– A single cable connection
integrating coil instrumentation
and heater circuits to IFS box with
a single connector to the
protection rack
MB protection rack connection
• Rupture of this connection
with powered protection
systems will cause discharge
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QPS electronics – quench heater circuits III
 Quench heater circuits - insertion
region magnets and inner triplets
AT-MEL-PM, R. Denz, CERN, CH-1211 Geneva 23
– Quench heater power supplies
installed in yellow racks
underneath the magnets (Q7 to
Q10) or in the corresponding
underground area (Q4 to Q6,
inner triplet, D1, D2, D3, D4)
– Separated connections for coil
instrumentation and heater circuits
with connectors on both ends
Insertion region magnet –
heater circuit connection
– Rupture of coil instrumentation
connection with powered
protection systems will cause
discharge
Insertion region magnet –
instrumentation
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QPS electronics – quench heater circuits IV
AT-MEL-PM, R. Denz, CERN, CH-1211 Geneva 23
 Switching off of quench heater power
supplies
–
Mandatory for access to IFS
boxes, power supply itself …
–
Recommended in case people
are working in the vicinity of the
heater circuits
–
Classical “lock-out / tag-out”
procedure can not be applied as
power supplies cannot be
padlocked
–
Once switched off an eventual
trigger is inhibited and the power
supply will discharge internally
within ten minutes time
–
Capacitor bank voltage can be
monitored by QPS supervision
with power supply switched off
Quench Heater Power Supply type DQHDS
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QPS electronics – quench detection electronics
 QPS racks in LHC tunnel and
underground areas
– Yellow QPS racks underneath
main dipoles
AT-MEL-PM, R. Denz, CERN, CH-1211 Geneva 23
– Protection rack type DYPG in
underground areas
– QPS current sensors type
DQCSD for protection of corrector
circuits
DQCSD type current sensors
(picture courtesy HCC TWIKI)
– Detection electronics is on the
same electrical potential as the
superconducting circuit / magnet
(up to ±1000 V DC to earth) !
– Only to be accessed by experts
• Also experts are supposed to
follow the rules …
Protection unit Q4.L8 & D2.L8
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QPS electronics – QPS controls
 QPS controls - expert mode
– Expert commands are required for debugging, QPS-IST and specific
hardware commissioning procedures
– Remote activation of quench heaters and energy extraction systems
• Strictly reserved for QPS experts
AT-MEL-PM, R. Denz, CERN, CH-1211 Geneva 23
• Not accessible to sequencer
• Not needed for LHC operation
– QPS-IST will be only executed with permit granted by HC
– During LHC hardware commissioning the QPS expert will only act on
request by EIC
• QPS expert cannot check himself whether a given circuit is ready
for a test  EIC’s responsibility (nobody is working on the
corresponding DFB / magnet, ELQA finished etc.)
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