1. The Control System for the LHC tunnel cryogenics Controlling Cool Accelerators Controle da Criogenia de Aceleradores de Partículas
Dr. Paulo Gomes
on behalf of the team CERN – TE – CRG
with the precious contributions of the colleagues:
Project Associates (NTU-Athens, AGH-Krakow)
Industrial Support
Cryogenic Operation
AB – CO

2. LHC : 27km proton-proton collider , 8 sectors of 3.3 km
Sector = 3.3 km
2 460 m
170 m
270 m

3. energy per beam: 7 TeV
luminosity: 1034 cm-2s-1
main dipoles field: 8 T
current: 12 kA
main magnets superconducting: 1200 D Q

4. QRL feeds He to the superconducting magnets
The arc: Most of a sector is composed of 154 dipoles and 40 quadrupoles which
are in series: dipoles in series & quads in series
operate at 1.9 K
the dipoles have a huge inductance 16H
contain
families of correctors in series
dipole correctors
The matching sections: small subsectors
operating at 4.5K
often standalone magnets
very special – often unique - magnets
The inner triplet: composed of very high gradient quadrupoles and a dipole which
operate at 1.9K
contains a complex electrical circuit with nested converters
in all magnets +QRL:
cryogenic sensors & actuators
super-fluid liquid He bath temperature: 1.9 K
cryo distribution line feeding magnets every: 107 m

5. 52 DFBs 5 000 instruments support and cool
Current Leads that power the magnets

6. RF superconducting accelerator cavities @ 4.5 K
grouped on 4 modules, on IP4
16 cavities
200 cryo instruments

7. a r c h i t e c t u r e industrial electronics → protected areas
CERN Control Centre
CRYO-SCADA
PVSS data server
CIET
PVSS data server
a r c h i t e c t u r e
surface - local control room
Ethernet
Technical Network
2 PLC
Siemens S7-400
500 ms cycle
8 FEC
WorldFIP – Ethernet
Gateway
500 ms cycle
4x Profibus
1.5 Mbit/s
4x WorldFIP
1 Mbit/s
100 m
100 m
alcoves - radiation free
industrial electronics → protected areas
FieldBuses ← large distances
CVs → electronics moved into protected areas
front-end electronics → radTol custom made
“intelligent”
CV positioners
with electronics
point-to-point
cables
tunnel - radiation
sector = 3.3 km
180
cryogenic CV
without electronics
100
FIP crates
custom rad-tol electronics

8. a few numbers (per sector)
2 000 sensors and actuators
100 FIP crates
2 Siemens S7-400 PLCs
500 Closed Control Loops
1 100 alarms & interlocks
PLC cycle 500 ms
5 600 objects of 16 types
lines of SCL source code
>3 Mbytes of machine code
AND...
the last 5 sectors were to be deployed at a rate of 1 new sector every 2 weeks

9. Databases are intensively used - LHC Controls Layout DB
17 055
instrumentation
channels
798 FIP crates
855 cards
1 738 Profibus
components
5 000 cable
numbers
LHC Layout Database
specification files
for manufacturing
FIP Crates
cabling files for
connecting &
inspecting cables
XML files for
Mobile Test Bench
specifications for
control software
PLC , FEC, SCADA

10. software production cycle
(existing) UNICOS framework (Unified Industrial Control System)
provides methodology & baseline tools to program industrial control CERN
(developed) generator of process specifications
extracts from DBs the list of all objects,
parameters, logical relations
(written) logic templates
similar code for objects of same family
(existing) UNICOS source code generator for PLC & SCADA
code compilation with UNICOS libraries
project deployment on field machines
(new) last 5 LHC sectors to be deployed at a rate of 1 new sector every 2 weeks
Proces Logic
*.xls
Process Logic
Layout DBs
Specs
*.xls
xls 2d 1d 1h
0.5d
(new) checker of specifications
(new) external function with common logic
(new) generator for specificities not covered by UNICOS gen
(new) run/check code on test PLC with simulated inputs
full sector code generation now takes 2 days
Checker
Code generation
Code generation
Template
Templates
Templates
Compilation
Test
Deployment

11. SCADA : Supervisory Control & Data Acquisition
CIET for Instrumentation Experts
40 synoptics, 35 bar-graphs, 60 alarms & interlocks
Repetitive panels use parameterized templates
200 panels / sector
Parameters generator, directly from DB
CRYO-SCADA for operation

12. Conclusions The control software production relies strongly on
a set of databases and on
a package of automatic generation tools,
which have been developed to create code
in several steps,
according to a well established methodology
The UNICOS automated generation & checking tools proved to be essential for flexible and robust PLC code generation
Thanks to extensive automatic code generation, we achieved
reduced software-production time and effort
increased code reliability
minimised risk of human mistakes
simplified long term maintenance
We managed to reach a deployment rate of 1 new sector every 2 weeks,
while in parallel giving support and modifications on other operating sectors
And…

13. 10 Sep 08 – the first proton beams in the LHC
At 10:28, one beam of protons was steered around the machine for the 1st time
Around 15:00 the other beam circulated in the second ring (anticlockwise) (

14. The 19 Sep 08 incident
In Sector 3-4, during powering tests (without beam) at high current (9 KA) for 5 TeV
a fault occurred in one electrical connection between magnets,
resulting in mechanical damage
and release of helium from the magnets into the tunnel.
During the ramping-up of current,
a resistive zone developed in the faulty connection
An electrical arc punctured the L He enclosure,
leading to a release/expansion of He into the insulation vacuum of the cryostats;
the pressure-relief system was not able to contain the rise of the He pressure;
large pressure forces displaced some magnets;
several magnets were contaminated with dust;
and had their multilayer insulation blankets damaged; (

15. Why did the LHC break down
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16. The measures taken
Sector 3-4 was warmed and 53 magnets were taken to the surface for repair or cleaning
New systems were installed, to ensure that similar incidents will not happen again:
enhanced protection system, with more sensitive measurement of resistance
(early detection of high-resistance, and quench, of electrical connections)
new pressure relief system, with installation of extra relief valves
(avoid high pressure to build inside the magnets)
the anchoring of the LHC magnets to the floor was strengthened
In all LHC sectors, high-current superconducting electrical connections were tested:
the ones with critically high resistance were repaired
the remaining ones do not pose problem for safely running below 5 TeV
( PR06.09E.html, PR13.09E.html)

17. The re-start plan
After finishing cooling and electrical-tests on all sectors,
the LHC beams will restart in Nov09;
During a few weeks:
Inject and capture proton beams in each direction,
for a few days, take data for collisions at the injection energy (0.5 TeV),
gradually increase energy up to 3.5 TeV per beam (= 1/2 nominal E);
Run at 3.5 TeV to collect data and gain experience
then, increase energy towards 5 TeV per beam;
At the end of 2010:
run with lead ions
After that:
shut down and do the necessary to have 7 TeV per beam in 2011 (

20. 10 Sep 08 - first beams @ CERN – media event
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