The procedure to replace CALO rectifier (AC/DC converter)

1

– Check low voltage (LV) readings for the problematic power supply (PS) to be sure that it is not some sort of software glitch [see Slide #3 for xCAL readout crates PS / Slide #4 for phototubes PS or PS/SPD VFE]

– If the problematic PS provides LV for detector photomultipliers:• switch off Medium Voltage on the corresponding side of the

corresponding detector (mandatory)• together with Shift Leader exclude corresponding HV node from BigBrother

tree (see Slide #5)• exclude problematic PS from DCS tree (see Slide #6) so data taking can

continue. Detector readout may stay in Global.

– If the problematic PS provides LV for readout crate:• ask Shift Leader to exclude corresponding detector from Global (in case of

ECAL: together with TCALO). If it is not possible (e.g. the problem occurred in the middle of data taking), exclude corresponding readout crate from the Global hierarchy (instructions are here:)

– Inform Shift Leader and descend downstairs. You will need a screwdriver.

Preparatory Steps

2

3

Checking LV readings (case of xCAL readout PS)

If PS is OFF,numbers are close to zero;status is not

green

INFDAI1_UI_DEN

4

Checking LV readings (case of phototube PS or PS/SPD VFE)

The fastest way to get all numbers is touse CADCSLV_UI_DEN “Hardware” tab.

Left-click on corresponding PS to getthe panel with operational details.

Description

Exclusion of HV node from Big Brother

Click on the lock andexclude entire node

for corresponding side

5

Exclusion of detector side from DCS tree

Click on the lock and exclude entire node

6

– Locations of rectifier units, protection relays and spare parts: see Slide #8– Check white boxes with protection relays to see if corresponding relay has

tripped [see Slide #9]. If boxes are locked, contact Eric Tomas or Laurent Roy.– If protection relay has tripped:

• Switch off corresponding rectifier (big green switch)• Arm the relay again (push up its handle). If it is not possible, contact Eric Tomas (if he is

not with you) – the problem is there.• As soon as relay is armed, try to turn on the rectifier. If relays trips again, replace rectifier.

– If protection relay is OK, check the status of corresponding rectifier [see Slides #10 and #11]• The rectifier is OK, if the big green button is illuminated and status LED shines with green.

Then the problem is elsewhere (99% probability).• If rectifier is not OK: try to switch it off and then back on. If it will not help, replace

rectifier

– Replacement of rectifier [see Slide #11]:• Obtain spare rectifier from PZ alcove [see Slide #8 and Slide #12]• Switch off corresponding rectifier (big green button)• Unscrew the unit and replace it with spare one• In case of protection relay trip: arm the relay• Switch on rectifier. If relay trips again, alarm CALO experts. Otherwise return to the

Control Room and start recovery procedure.7

Downstairs

Gateway to LHCb detector

Exit from elevator

DELPHI

COUNTING HOUSE (D)

PZ alcove with spares (last floor)

Protect.relays

CALOrectifiers

8

Protection Relays

Boxes with protection relays

Check the position of handlefor corresponding crate

(they are labeled)

9

Rack with Rectifiers

CALO rectifiers (second rack)

RCM units

10

Rectifier units

Rectifier Units

ScrewsStatus LED

11

Check if light is ON(be careful: some lights

are really dim!)

ON/OFF switch

One rectifier unit

Spare Parts

Spare unitsof rectifiers

Location: PZ alcove, last floor (take stairs)

12

– In case of problematic PS for xCAL readout:• Turn on the power supply via INFDAI• Restart DAQ project for the corresponding side of the

corresponding detector via Service+ (will take some time).• Together with Shift Leader include corresponding detector

itself (if it was excluded) or disabled power supply back into Global (if corresponding detector was not excluded)

– In case of phototubes PS:• Turn on the power supply via CALO_HV_top• For affected detector part:

– restart HV-control project via Service+ (will take some time).– initialize the system like after power cut, set Medium Voltage and apply

HV-recipes (see presentation of Yuri Guz for details: https://indico.cern.ch/conferenceDisplay.py?confId=181183 )

• Together with Shift Leader include back into LHCb_top and Big Brother trees the nodes which were excluded 13

Recovery