New HV test specification for the LHC

N. Catalan for the EI section

The current specification

• EDMS 90327 from 2004 (LHC-PM-ES-0001 rev. 2.0)

• Refers to equipment tests from manufacturing to installation in LHC– Operation conditions

define the lower voltage– Apply decreasing voltages

through manufacturing • Only single circuits vs.

ground are considered

The voltage to ground for each circuit

• Two different sources of voltage during operation– Energy extraction at

maximum current U=RI– Quench voltage from

simulations• Either/or for all

circuits but for dipoles• Safety factor 1.2

applied– Except for dipole circuit

• Missing RCO2xV+500Imax x REE 1.2xV

From ElQA EDMS 788197 (2008)

Test Voltage Test Test Voltage Test Test Voltage Test

voltage ramp duration voltage ramp duration voltage ramp duration

rate rate rate

[V] [V/s] [s] [V] [V/s] [s] [V] [V/s] [s]

Main Dipoles (MB) 600 2 300 600 2 300 1900 2 300Main Quadrupoles (MQ) 120 5 300 120 5 300 240 5 300Spoolpieces (MCS, MCD)Arc correctors (MSCB,MO) 300 10 180 300 10 180 600 10 180Trim Quads (MQT, MQTL, MQS)Matching MQM (1.9K)Matching MQM (4.5K)Matching MQY 60 10 180 60 10 180 120 10 180LowBeta Quads 210 5 300 210 5 300 420 5 300Separator magnets 300 10 180 300 10 180 600 10 180

TP4-B TP4-D TP4-E

CIRCUIT type

240

180

240

240

480

360

480

240

180

240

480240

10 300

10 180

10 180

10 180

10 300

10 180

10

10 300

10 180

10 180180

10 180 10 180

Insulation tests during TP4-e tests • Different classification

from EDMS 90327• Different tests for air

cooled leads1. each circuit tested at a

lower voltage one by one versus all other circuits and ground.

2. all circuits of one chimney are tested together at higher voltage level vs ground.

RQ vs Spools• M1/M2 lines and M lines run along

together• General protection will run down all of

them at the same time

Line N circuits

• Bus-bar run together along the same cryogenic line

• Metallic braids already gave insulation problems

• MQT, MQTL, MQS, MSCB with energy extraction

• MO, MQM with no EE

Monday Morning Meeting : 3rd of May 2010

A. Perin AT-ACR, 8

Spool busbar routing inside DFBAs

Busbars in lines M1 & M2 Busbars

merged with line N

All 600 A busbars in the same duct

CorrectorsSpoolBundles of n x 4 busbars

New voltage to ground values• Which electrical circuits

have bus-bars running in the same cryo-line?

• Only circuits whose voltage is coming from EE should be taken into account.

• Nested circuits• Maximum operation

voltage x1.2

• Maximum operational voltage against any neighboring circuit

• Tested circuit vs. all others + ground

Voltage level proposal

• HV tests with new voltages need to be implemented prior to cool-down in 2011/2012

• RCO/RCB Lemo connector insulation weakness– Will be inspected in the next technical stop– Repair during the Xmas break?

• Tests of the two bus-bars of RQ?– Implemented during the assembly in the long

shutdown in 2012– Is it possible to interrupt the circuit?

Practical considerations

• Magnet instrumentation check– Local measurement at warm and cold– Continuity and resistance of diagnostic

Vtaps– Resistance and insulation of QH– QH against coil & ground

• ElQA test procedure needs to be updated– Can be done at the same time as HV

qualification for the magnet

MIC tests introduced during 2009

Quench heaters vs. ground

• Not specified in the note

• Minimum 2x450+500 = 1400 for most circuits

• Voltage on the coil during quench added to this value

• Not taken into account in US magnets during manufacturing

• Needs to be reviewed

Where is it coming from?

• Tests in SM18 at cold • Reception tests in b181(at warm) for US

magnets• Minimum voltage retained• QH/coil vs. ground values?

MIC proposed HV values

• ElQA test procedure 788197 to be rewritten and reissued

• Higher values to be applied almost in all correctors RQ(M) and RQ circuits

• MIC test to be added• Hardware modifications in DFB

chimneys to remove limitations to be implemented– During Xmas stop– During long shutdown

Conclusions

• Machine will be emptied • Three days cooling tower cleaning

will stop active cooling on DFBs• All DFBs SAM and SC links will warm

up above 120K• According to A. Perin that will mean

a full thermal cycle• What parts of ElQA need to be

redone?

Xmas break ElQA tests

From ElQA test procedure

ElQA • Only TP4e tests HV in the arc– One week per sector for a team of 2-3

people– Enough resources in house with the

eventual help of other sections– Two sectors in parallel.– To be fitted in the schedule

• Full TP4e and MIC in the SMA magnets