TE/MPE/EE

Summary of Electrical Engineering SessionEd & Knud

K. D

ahle

rup-

Pete

rsen

TE/

MPE

/EE

23 N

ovem

ber 2

012.

RB – RQ EE facility consolidation & upgrades (Bozhidar):

- Motivations: Readiness for safe 7 TeV operation, increase lifetime and reliability, eliminate over-voltages, smoothen the voltage waves upon commutation, meet new requirements, reduce tear and overcome flaws detected during operation.

- For most activities the equipment is ready and tested – BUT NOT FOR ALL (e.g. RL4,6,8 & 10: adequate contactor to be selected).- For some subjects there are logistics and practical difficulties – but no technical showstoppers.

- The upgrade cannot start before 1st May 2013 because of U70 operation @ IHEP - IF A CONTRACT CAN BE MADE AT ALL! Depends on goodwill of DG Prof. Tyurin. We are pursuing a 30 man-month resource agreement . BUT: a back-up solution is in preparation.

- Following the wish of our DG, contracts with CERN –member states shall be favored w.r.t. non-member states agreements. CONSEQUENTLY, we are in a process of phasing-out with Russia and phasing-in with member-state contracts.

- It is not foreseen to replace the 13 kA EE systems in any foreseeable future. No opening failures ever, no loss of redundancy ever.

- Few spurious openings. Origin of LAST EVENT (S67), however, not yet disclosed (BCM removed for testing in January).

- The 2 hours maximum cool time is a hard limit, given by the design of the air-to-water heat exchanger.

- The exercises require little help from other services inside or outside the EE team.

- The problem with the voltage measurements of U-DUMP is understood and solved (it was a ground plain without ground connection on the ‘measurement board’). Corrected everywhere.

LHC Machine

TE/MPE/EE

Summary of Electrical Engineering SessionEd & Knud

K. D

ahle

rup-

Pete

rsen

TE/

MPE

/EE

23 N

ovem

ber 2

012.

600 EE facility consolidation & upgrades (Gert-Jan):

- Motivations: Achieve longer lifetime and higher reliability, cure certain teething problems, apply remedies for flaws detected during operation since LHC start-up.

- Emphasis on breaker upgrade, with principal faults being the main axis rupture (concept mistake, now corrected on new production (but it doesn’t help us much) and detection of overheating by contact pressure release.

- Origin of the loosening of the holding coil has been identified to design and material mistakes of the central U- shaped supports. Remedy: Filling the gap so that the coil cannot move. We believe that basically ALL Perfiliev problems (closing failures) are due to this flaw!!

- Overheating can have serious consequences (fire) as EE systems placed in high equipment density areas.

- Question from Edward: Signal from thermostats on the three equalizing resistors: Alarm or interlock? Threshold? Switching @ 130 deg. C. Better interlock as risk (= frequency of failure x consequences) is high.

- Need for repetition of opening time measurements: YES, all breakers have been partially opened and modified. To be considered as a commissioning FROM ZERO.

- The upgrade also relies on the availability of new DQAMS boards (24-bit ADC for high-precision voltage measurements). Reiner explain that this could happen to be ready only AFTER LS1. We understand the reasons and will live with this situation.

- The installed supervision software is working well and has already produced lots of useful information. In fact, our regular preventive maintenance directly rely on this info.

- Also problems with contract: Verbal agreement by BINP DG Prof. Academician A. Skriensky, but no contract signed yet. Also here: Phasing out to become less dependent on Non-member state assistance.

LHC Machine

TE/MPE/EE

Summary of Electrical Engineering SessionEd & Knud

K. D

ahle

rup-

Pete

rsen

TE/

MPE

/EE

23 N

ovem

ber 2

012.

Cabling Issues (Gert-Jan):

- Motivations: Being able to pull out the yellow racks to the centre of the transport zone. To reduce pick-up of noise through the large loop of the existing instrumentation cables and the power busbar on all Q8, Q9 and Q10 circuits in the tunnel (except Q10.L2 already upgraded). To secure the cables of the DYPB racks against damage from the IC Train and other tunnel activities. To make sure that connections of the 13 kA water-cooled cables to the EE busways (conical electrical/hydraulic connectors) are correctly mounted (Bozhidar).

- Baseline approach so far: EN/EL shall provide and install all required new cables during LS1.

- EN/EL was contacted 6 months ago by Gert – no answer was received.

- Securing cables in the tunnel is under the responsibility of MPE. Help from AGH.

- EN/EL has communicated their limitations in terms of resources.

- A compromise can maybe be found through pre-manufacture by EN/EL of many of the new cable segment before LS1.

- Campaign for determination of cables shorter-than-required will be performed during the first week of access to the tunnel during TS4. This will give us the situation in half the machine – scaling with smaller error.

- The new cabling of the DYPB yellow racks will be ‘clean’. - elimination of all patches, short and adapted interconnecting cable links.

LHC Machine