Status 100% 30% 100% STATUS REPORT on Electromagnetical Perturbations on the Hardwired Safety Alarms  The investigations to understand the causes of hardwired alarm level 3 induced by electromagnetic perturbations in correspondence of the 18kV power breakdown indicated two actions: A Implementation of a low-pass filter on the input of the hardware-triggering unit, A Revision of the shielding and grounding of the existing hardwired network. A Implementation of a data logger on the main hardwired links.

Status OK OK OK OK STATUS REPORT on Electromagnetical Perturbations on the Hardwired Safety Alarms  Implementation of a low-pass filter on the input of the hardware-triggering unit A Designed using MATLAB and test field measurements A Installed, tested and in operation since May 2001 A NO spurious alarms due to Electromagnetical Perturbations have been recorded A Inspected by TIS and their EMC consultant

Triggering unit’s equivalent circuit: with and without the input filter.

Comparison between the experimental data and the simulations

Note that the input voltage of the triggering units follows closely the perturbation in case A Note that the presence of the input filter avoids that short-lived events trigger alarm while long- lived events trigger alarm

Status OK OK Planned Planned STATUS REPORT on Electromagnetical Perturbations on the Hardwired Safety Alarms  Revision of the shielding and grounding of the existing hardwired network. A Review of the existing cable paths and rack location A First TIS and EMC consultant audit A Recommendations by TIS expected middle October 2001 A Work on the cable connections, terminations and shielding start middle October 2001

Status OK STATUS REPORT on Electromagnetical Perturbations on the Hardwired Safety Alarms  Implementation of a data logger on the main hardwired links. A Design, installation and testing of a LabVIEW data logger

Photos of the Installation Filters Data Logging HW Alarm Terminal blocks