1. Mikhail Ovsienko TE-MPE-EE 27.03.2014
Upgrades and Activities on 13kA EE systems done during LS1 by IHEP team 
Mikhail Ovsienko TE-MPE-EE

2. The following works were executed in the period from June 2013 up to March 2014 by a team of specialist from IHEP, under supervision of CERN personnel and the help of a team from AGH-UST.
General maintenance of the 13kA EES switches (VAB 49)
Retightening of all bolted electrical connections on the power busbars of the 13 kA EES
Installation of Snubber capacitors in RQD/F EE systems
Replacement of arc chambers for RQD/F EE switches
Mechanical modification in all RB dump resistors (DQRB)
Dump resistors re-configuration
Modification of the BCM modules for improving protection of VAB49 holding coil.
General maintenance of Solenoid and Toroid switches on Atlas
Works in Bld377 on 13kA EES test bench

3. General maintenance of the 13kA EES switches (VAB 49)
All 256 switches installed in the 13kA EES have been
Opened
Cleaned
Inspected and repaired if necessary
Adjusted according to producer recommendation
Tested in a local mode

4. General maintenance of the 13kA EES switches (VAB 49)
Non conformities observed during the maintenance
Disrupted micro switch
activator and wires 4

5. General maintenance of the 13kA EES switches (VAB 49)
Non conformities observed during the maintenance
Broken insulator
In comparison with previous maintenance the quantity of broken insulators decreased.
Maintenance pcs
Maintenance pcs 5

6. General maintenance of the 13kA EES switches (VAB 49)
Non conformities observed during the maintenance
Deformed pins
inside “Burndy” connectors
for VAB 49 holding coil .
This fault could provide
unexpected switch opening 6

7. General maintenance of the 13kA EES switches (VAB 49)
Non conformities observed during maintenance
Broken ODU connectors for VAB49 fast opening circuit
There are two types of breakages:
Melted pins
Unfixed inner insulator 7

8. General maintenance of the 13kA EES switches (VAB 49)
Damage observed during maintenance
UA 47 falling scaffold part damaged X1 connector of QF damp resistor 8

9. General maintenance of the 13kA EES switches (VAB 49)
Damage observed during maintenance Have been discovered missing neutral and one of the three phase in UA67 three phase main. Probably this malfunction may have provoked the unexpected opening of EES switches As a result of this malfunction were damaged two time relays in side of the DJRQ 9

10. General maintenance of the 13kA EES switches (VAB 49)
Damage observed during maintenance
In the RQF system in UA 83 a resistor in the interface
module was discovered broken insulation to ground
In the RQF in UA83 the connector SK102 in BCM module 2 was discovered not properly soldered (pin N10). This malfunctions also can provoke unexpected opening 10

11. General maintenance of the 13kA EES switches (VAB 49)
All non-conformities discovered during general maintenance were corrected and repaired 11

12. Verification of all bolted electrical connections on the power busbars of the 13 kA EES
All bolted electrical connections were checked by torque key set up to the180N.
There were discovered a few non tightened nuts.
On UA 23 RB busway have been found broken lamella contact (Multi Contact device). The nature of this breakage was incorrect assembling during the installation. The problem has been solved. 12

13. Installation of Snubber capacitors in RQD/F EE systems
The benefit: To suppress the voltage transient perturbations in the circuits during switch commutation and to make the opening process lighter by reducing the electrical arc existence
All 16 EE systems of RQD/F circuits were equiped. Four snubber capacitors per system + associated auxiliary boards  in total 64 snubbers and 64 boards

14. Replacement of arc chambers for RQD/F EE switches
The replacement of the existing 200V quadrupole arc chambers by new 1kV units was combined with snubber capacitors installation.
12 EE systems were equipped by 1kV dipole arc chambers .
Four EE system in sectors 1-2 and 2-3 were installed earlier.

15. Mechanical modification in all RB dump resistors (DQRB)
Mechanical modifications in dipole dump resistors was done by AGH team.
IHEP team took part only in few moments concerning repairing of some copper leads

16. Dump resistors re-configuration
The expected new conditions in LHC after LS1 require a new configuration of the dump resistors in RB and RQD/F EE systems
RB_EE system  requires only cable reconnection to get all three resistors in parallel
Before LS1
t=55 sec
After LS1
t=102 sec 16

17. Dump resistors re-configuration
RQD/QF_EE system  requires exclusion of additional 20 mOhm resistor, to get value of dump resistors 6.6mOhm or 7.7mOhm
Additional 20mOhm resistor shorted and ready to use if necessary
Before LS1
Rdump=27.8mOhm t=9.8s.
Rdump=28.9mOhm t=9.4s.
After LS1
Rdump=6.6mOhm t=32.15s.
Rdump=7.7mOhm t=28.6s. 17

18. Modification of the BCM modules for improving protection of VAB49 holding coil.
As a part of preventive maintenance it has been decided to replace relays in all EE systems (RB and RQD/F) 8 relays per EE system  32 systems  256 relays in total
At the same time to improve holding coil protection has been decided to replace circuit breakers Q5,6,7,8 in BCM 8 circuit breaker per EE system  32 systems  256 breakers in total

19. All replacement were done
Modification of the BCM modules for improving protection of VAB49 holding coil.
All replacement were done
BCM before
modification
BCM after
modification 19

20. General maintenance of ATLAS solenoid and toroid switches
Switches were:
Opened
Cleaned
All bolted electrical connections were checked
All 32 arcing contacts were cleaned and replaced by new if necessary
All arcing contacts pressure force were adjusted up to correct value
All main contacts were cleaned
All 96 main contact springs were replaced and adjusted according producer recommendations
We found possible malfunction of the Toroid switch, under certain conditions. The problem was discovered when, as in the situation with overheating , one contactor, instead of two, was conducting 20 kA. This malfunction defined by design feature. The owner of equipment was informed and problem have been discussed. To solve this problem was decided to install additional sensors to control state of contactors.

21. Work in Bld377(extention) on 13kA EES test bench
Installed and electricaly connected
4 quadrupole and 3 dipole resistors 21

22. Work in Bld377(extention) on 13kA EES test bench
Designed and manufactured two commutation boards in order to get the flexibility in the choice of Dump resistor value
Commutation boards
for dipole resistors
Commutation boards
for quadrupole resistors 22

23. Thank You