Upgrades and Activities on 13kA EE systems done during LS1 by IHEP team

Upgrades and Activities on 13kA EE systems

done during LS1 by IHEP team

Mikhail Ovsienko TE-MPE-EE 27.03.2014

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 2

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

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Non conformities observed during the maintenance

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Disrupted micro switch activator and wires



5

Broken insulator

In comparison with previous maintenance the

quantity of broken insulators decreased.

Maintenance 2012 - 5pcsMaintenance 2013 - 1pcs



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Deformed pinsinside “Burndy” connectors for VAB 49 holding coil .

This fault could provide unexpected switch opening


Non conformities observed during maintenance

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Broken ODU connectors for VAB49 fast opening circuitThere are two types of breakages:• Melted pins• Unfixed inner insulator


Damage observed during maintenance

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UA 47 falling scaffold part damaged X1 connector of QF damp resistor


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

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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

All non-conformities discovered during general maintenance were

corrected and repaired

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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.

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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

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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.

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• 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

Mechanical modification in all RB dump resistors (DQRB)

thermal

crack and shortexpansion

Modification

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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

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Before LS1

After LS1

t=55 sec

t=102 sec

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

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Before LS1

After LS1

Rdump=27.8mOhm t=9.8s.




• 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

Modification of the BCM modules for improving protection of VAB49 holding coil.

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All replacement were done

Modification of the BCM modules for improving protection of VAB49 holding coil.

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BCM before modification

BCM aftermodification

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.

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Work in Bld377(extention) on 13kA EES test

bench

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Installed and electricaly connected 4 quadrupole and 3 dipole resistors

Work in Bld377(extention) on 13kA EES test

bench

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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

Thank You

Upgrades and Activities on 13kA EE systems done during LS1 by IHEP team

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