1. Major Event 76537 Fire on batteries of UPS ESS118/5CX
Date of event: Saturday 25th May 2019, 22H42
Davide Bozzini, on behalf of EN-EL

2. Calendar of LS2 activities
Major event – 22h42

3. Sequence of events
22h42 Fault on UPS ESS118/5CX and fire alarm in SDX5
23h10 Fire detected and extinguished in SCX5 in room 3562/R-403
Finding that UPS ESS118/5CX battery rack is completely destroyed
23h45 EN-EL stand-by on site
00h10 UPS ESS118/5CX isolated, EOD2/CX5 reconfigured in by-pass mode
07h00 Detector Safety System (DSS system) back to nominal conditions
09h00 Electrical network hooked on DSS system back to nominal
09h30 End of EN-EL intervention
More details available here:

4. Location (SCX5) 3562/R-403 CMS – Control room
Room hosting UPS ESS118/5CX
SDX5 – Fire detection triggered

5. Single line diagram LHC-EB500-LV
UPS ESS118/5CX
CMS control room
CMS DAQ servers room

6. Damaged batteries in 3562/R-40

7. Consequences EN-EL next steps
Supply of CMS DAQ Servers room supplied through EOD2/5CX in by-pass mode (No UPS)
Request from CMS to avoid any power cut on EOD2/5CX
AUG tests planned at point LHC-5 for Monday 27th May have been cancelled
CMS control room severely impacted
EN-EL next steps
Root cause of fault to be investigated with the contribution of UPS manufacturer and systems experts
Contribution and support to HSE investigation
Temporary/alternative UPS sources under study in collaboration with CMS
AUG tests at point LHC-5 to be rescheduled