1. Low Voltage LB status RPC detector and trigger group

2. Equipment type Totalinstalled spare % of spare SY1527 54125,0% A3485 53266,7% A3512NHV127116119,5% A1676BC A16762017317,6% EASY3000SCRATE403825,3% EASY3000CRATE4439512,8% A3000FBFAN2723417,4% A3486S_380MAO AC/DC1210220,0% A3009LV DC/DC1059699,4% A3801ATemperature AC/DC1714321,4% RPC HV distributor BarrelHV Distribution Box373525,7% A3486S_230 EndcapMAO AC/DC131218,3% RPC HV distributor EndcapHV Distribution Box24 00,0% A3016LV DC/DC686446,3% RPC LinkBoardBoxLBB1059699,4% RPC MasterBoardMLB3513004916,3% RPC SlaveBoardSLB5745007014,0% RPC ControlBoardCB12412043,3% RPC LB FrontPanelLB FP12512054,2% RPC OptoBoxOB1410440,0% 7/6/10Pigi Paolucci - CMS LV review2

3. Low Voltage Link Board status After many failures in the link board system the RPC-Trigger community decided to investigate all the possible causes analyzing not only the LB system but also the LV system: A3016 boards MAO LV and MAO power cut and power cycle Power off and on of the link box CAEN firmware 7/6/103Pigi Paolucci - CMS LV review

4. A3016 behavior cutting the MAO 3Phase

5. LV link board Schema 1.MAO 48 service from BC – Output current = 15-18 A 2.EASY 3000 – Joint 48 Power & Service 3.Output power from A3016: – 2.5 Volts / 5.0 Amp – 3.5 Volts / 10.0 Amp MAO SY1527 48 service 3-phase EASY A301 6 48 service 48 power Link Box 7/6/105Pigi Paolucci - CMS LV review

6. What powering OFF the MAO in the proper ways ? Powering OFF the MAO via SY1527 or using the interlock placed on the front OK 7/6/106Pigi Paolucci - CMS LV review

7. What powering OFF the EASY in a “bad” way ? Powering OFF the EASY 3000 crate removing the power or service connector from the back OK 7/6/107Pigi Paolucci - CMS LV review

8. What cutting the MAO 3-phase ? Shutting-down the MAO cutting 3-phase oscillation does not depend from the MAO load (from 4 A to 18 A) sometimes 2 oscillations in few msec oscillation disappear separating the 48 power from the 48 service No other ways to reproduce it NOT OK 7/6/108Pigi Paolucci - CMS LV review

9. What happen cutting MAO 3-phase ? MAO goes OFF in 2 steps: from 48 to 22 V and a from 22 to 0 V The A3016 channels go off when MAO voltage is around 22 V and this takes about 250-300 msec (fixed load on the MAO) Around 22 V the boards begin to work not properly (Vcc goes from 12 V to 6 V) and generates oscillations on Vout. 7/6/109Pigi Paolucci - CMS LV review Vmao = 22 V Vcc = 12 V 6 V 7/6/109Pigi Paolucci - INFN

10. Mao behavior during 3Phase glitch

11. T0T1 At T0: Turn off the 3-phase switch MAO starts ramping down with a “dummy load” - NO status changing After a while, it gives UNV status, but the channel keeps status ON. At T1: MAO ramps down with different slope (real load) At T2: MAO swiched ON (600 ms from T0). Switching OFF-ON in <1sec, no IntFail status is generated by the MAO and the channel goes back to the 48V without any alarm acknowledge. T2 Scope output MAO A3016 40 V 7/6/1011Pigi Paolucci - CMS LV review

12. What we have done ! Already implemented Solutions: Introducing a big capacitor (33 mF) between the service and power line of the EASY Improve the A3016 firmware Modify the MAO firmware Long Term Solutions: 1.Designing a protection on the Link Box LV lines (see tomorrow meeting) 2.Separating the 48 service and power of the EASY ? 7/6/1012Pigi Paolucci - CMS LV review OK Under test now

13. A3016 firmware requirements Couple of channels in tracking mode (ON/OFF/Trip at same time and with one command). – delay between the 2 channels must be less than 1 msec Ramping up in stepping mode: – overshoot first steps < 10% of the setting voltage – overshoot of the last step must be < setting voltage – voltage must be always < setting voltage (no overshoot above max value) – Over-voltages are very dangerous for the LB. – no under-voltage dips are allowed after VCC2.5 gets above 2.0 V – no under-voltage dips are allowed after VCC3.3 gets above 1.2 V – total time to reach the setting voltages (3.5 V and 2.5 V) should be less than 60 msec 7/6/1013Pigi Paolucci - CMS LV review

14. MAO firmware requirements The MAO behavior is case of glitch on the 3- phase line is potentially dangerous for the LV system. Turn OFF the MAO when the Vmon < 43-40 Volts in about 100 msec and require an acknowledge afterwards to bring the channel back to ON. – In 100 msec firmware measures the voltage 5 times, should be enough. – After 100 msec the MAO voltage is around 35-38 V and it is enough to shut-down properly the A3016. 7/6/1014Pigi Paolucci - CMS LV review

15. 7/6/10Pigi Paolucci - CMS LV review15 MAO Vcc Vout New MAO firmware old MAO firmware Oscillations on both Vcc and Vout 200 msec OFF – 38V 43V New MOA firmware

16. 7/6/10Pigi Paolucci - CMS LV review16 Rumping up - new A3016 firmware 50 msec 80 msec 2.5 V 3.5 V No overshot over the max voltage

17. 7/6/10Pigi Paolucci - CMS LV review17 Overshot - new A3016 firmware Overshot < 10-15% voltage set

18. 7/6/10Pigi Paolucci - CMS LV review18 Channels delay- new A3016 firmware 2 msec Delay stable and < 2 msec (depends on the charge)

19. Results with C and diode power service 1.5 sec 7/6/1019Pigi Paolucci - CMS LV review

20. Results with C and diode 2.5 V 48 V No spikes or oscillations 600 msec 7/6/1020Pigi Paolucci - CMS LV review

21. Conclusions Capacitor protection is working safe New firmwares are ready and under test at CAEN. Next week will be tested at 904 Both Capacitor boxes and firmwares have been payed by INFN (M&O-B 2010)  16 Keuro Hardware protection of the Link Box is in any case necessary 7/6/10Pigi Paolucci - CMS LV review21