MAINTENANCE AT LNLS

1. 4th POWER CONVERTERS FOR PARTICLE ACCELERATORS WORKSHOP MAINTENANCE AT LNLS CLEBER RODRIGUES ELP - Power Electronics Group LNLS – BRAZILIAN SYNCHROTRON LIGHT LABORATORY CNPEM – NATIONAL CENTER OF RESEARCH IN MATERIALS AND ENERGY SEPTEMBER/2014

2. OUTLINE INTRODUCTION MAINTENANCE STRATEGY OVERVIEW OF LNLS POWER SUPPLY SYSTEM EXAMPLES OF CORRECTIVE MAINTENANCE CONCLUSIONS

3. OUTLINE INTRODUCTION MAINTENANCE STRATEGY OVERVIEW OF LNLS POWER SUPPLY SYSTEM EXAMPLES OF CORRECTIVE MAINTENANCE CONCLUSIONS

4. 1. INTRODUCTION Hostel & Restaurant Sirius Accelerator engineering and instrumentation The LNLS: Located in Campinas (São Paulo state) Part of CNPEM (National Center of Research in Energy and Materials) Bioethanol center Molecular and Structural Biology and Proteomics UVX Microfabrication and Nanoscience

5. 1. INTRODUCTION 500 MeV booster The UVX source: 120 MeV LINAC (1995) 1.37 GeV Storage Ring (1996) 500 MeV Booster (2001) 120 MeV linac (underground) 1.37 GeV storage ring

6. LINAC view StorageRingViewbeforeshieldinginstallation (1995) 1. INTRODUCTION The UVX source:

7. 1. INTRODUCTION Responsible For (UVX): More than 200 DC Current Source Power Supplies (design, mounting, maintenance): 5 to 500A, 10 to 900V, up to 270kW About 20 DC Voltage Power Supplies for valve heaters (design, mounting, maintenance) 15 AC Power Supplies for Titanium Sublimation Pump (maintenance) About 200 7kV/30mA Power Supplies for Ion Pump (maintenance) Two 80 keVElectron Guns (design, mounting and maintenance) The Power Electronics Group (ELP): 3 Engineers 5 Electronic Technicians 2 Students Activities in Sirius: Design, prototype mounting, tests and coordination of the building of all current source Power Supplies

8. 1. INTRODUCTION Storage Ring and LINAC Power Supplies of UVX (1) SMPS – Switched Mode Power Supplies

9. 1. INTRODUCTION Booster and Transport Lines Power Supplies of UVX

10. OUTLINE INTRODUCTION MAINTENANCE STRATEGY OVERVIEW OF LNLS POWER SUPPLY SYSTEM EXAMPLES OF CORRECTIVE MAINTENANCE CONCLUSIONS

11. 2. MAINTENANCE STRATEGY The control software: Developed in 2007 by LNLS staff using ASP language

12. 2. MAINTENANCE STRATEGY Tools of the software: Registration of every maintenance and operation events Registration of every equipment unit and its present position Easy search of events, equipment localization, etc. List of pendent preventive maintenance Failure statistics Spare parts control Equipment documentation Etc. Time for maintenance (usually): Short stops: one day per month Longer stops: approximately 6 weeks per year, which can be divided according to needs (2 3-week stops, 6 1-week stop, etc.)

13. 2. MAINTENANCE STRATEGY Types of preventive activities with Power Supplies: Bolts and nuts retightening Almost all PS, once each 2 years Substitution of ventilators Only the PS which have critical ventilators (PS that don’t work without them) Once each 2 or 3 years Problems with bad quality ventilators Washing or substitution of the ventilator filters Once a year Visual verification of ventilators Only in the case of non critical ventilators, each 6 months Output current ripple and output voltage measurements All PS, once a year Measurement of current distribution in the modules Only PS with modules operating in parallel Once each 6 months

14. OUTLINE INTRODUCTION MAINTENANCE STRATEGY OVERVIEW OF LNLS POWER SUPPLY SYSTEM EXAMPLES OF CORRECTIVE MAINTENANCE CONCLUSIONS

15. 3. OVERVIEW OF LNLS POWER SUPPLY SYSTEM Power Supplies with Linear Regulation (BCA model): Usually +/-10A, +/-10V output Operating since 1993 Gradually been substituted by SMPS topologies Periodic activities: ripple measurement, retightening, ventilator exchange

16. 3. OVERVIEW OF LNLS POWER SUPPLY SYSTEM PS with combined Linear Regulation and SMPS (BCB model): Output current: 5A, 6A or 10A (bipolar); output voltage: 10V or 15V Operating since 2001 High reliability Problem: substitution of PC power supplies Periodic activities: ripple measurement, retightening, ventilator exchange

17. 3. OVERVIEW OF LNLS POWER SUPPLY SYSTEM Bipolar SMPS (PSA and PSB models): Usually +/-10A, +/-10V output Periodic activities: ripple measurement No ventilator No need of retightening observed up to now PSA Model (since 2008) PSB Model (since 2012) Cratewith 4 unitsof PSB Model

18. 3. OVERVIEW OF LNLS POWER SUPPLY SYSTEM Unipolar SMPS: Output: 10A/26V or 20A/50V Operating since 2001 High reliability Periodic activities: ripple measurement, retightening, ventilator exchange

19. 3. OVERVIEW OF LNLS POWER SUPPLY SYSTEM SMPS Power Supplies with parallel modules: Output: 225A/22.5V Operating since 1995 Periodic activities: output ripple and module current measurements, retightening, ventilator exchange

20. Power Supplies with a series association of: 12-pulse controlled rectifier 10 parallel module SMPS Output: 300A/900V Operating since 1995 Periodic activities: output ripple and module current measurements, retightening, ventilator exchange 3. OVERVIEW OF LNLS POWER SUPPLY SYSTEM

21. Power Supplies with a series association of: 12-pulse controlled rectifier 10 parallel module SMPS 3. OVERVIEW OF LNLS POWER SUPPLY SYSTEM

22. 3. OVERVIEW OF LNLS POWER SUPPLY SYSTEM Power Supplies with controlled rectifier and parallel bipolar SMPS: Output: 225A/45V Operating since 1995 Periodic activities: ripple measurement, retightening, ventilator exchange and ventilator verification

23. OUTLINE INTRODUCTION MAINTENANCE STRATEGY OVERVIEW OF LNLS POWER SUPPLY SYSTEM EXAMPLES OF CORRECTIVE MAINTENANCE CONCLUSIONS

24. Ch3 Ch2 4. EXAMPLES OF CORRECTIVE MAINTENANCE Ch1 Ch2 Thyristors: The storage ring dipole PS (300A/900V – controlled rectifier + SMPS) was built in 1995 using SCRs from Aegis brand 2001: due to the great number of failures of these thyristors, they were substituted by Semikrondevices 2004: Many PS shutdowns with the indication of “overcurrent in the capacitive filter” It was observed (after spend much time!) that 2 thyristor, after warming (≈0,5 hour), triggered before pulses in their gates, increasing the rectifier output voltage ripple The only difference observed among these units and the “normal ones” were a decreasing in the RGK resistance (≈30Ωto 20Ω) A thirdunithadthesameproblemwiththeresistance, butdidn’taffectthe PS behavior The three units were substituted and no more problem were found up to now One faulty thyristor was sent to Semikron, but no feed back was received Ch3 Ch1 Pulses before (above) and after (below) warming in one faulty thyristor Ch1: Anode-cathode voltage (200V/div) Ch2: Capacitive filter current (5A/div) Ch3: Gate-cathode voltage (2V/div)

25. 4. EXAMPLES OF CORRECTIVE MAINTENANCE BJTs (Power Supplies with Linear Regulation Stage): It was observed that the BJT gain decreased with the time, leading to problems to reach the maximum current. To solve this problem it was necessary to change the bias point or substitute the BJTs In 2004 (after nearly 10 years of operation) all the BJTs were exchanged Some years later this problem started again, which led to the substitution of this model in the critical positions (storage ring steering magnet PS) by the PSB model (switched) in 2011/2012 In order to save time and money with the ventilator substitutions in these power supplies, it was tried to turn on them only when the heatsink reached a high temperature. This change increased the number of BJT failures due to the junction temperature variation

26. 4. EXAMPLES OF CORRECTIVE MAINTENANCE IGBTs: The high current PS (225A and 300A) which have parallel modules to share the output current uses IGBTs as switch (13 PS / 82 modules) During the first 10 years of operation no failure with IGBTs Now the number of events has been kept once a year, but in the 2 last years they were catastrophic, damaging all switches of the PS Aging of the IGBTs? Substitution? (1) (1) (10) (1) (1)

27. 4. EXAMPLES OF CORRECTIVE MAINTENANCE Other activities: Electrolytic Capacitors In 2010, after 14 years operating and more than 50,000 hours, the power electrolytic capacitors were substituted No important changes were observed in the old capacitors Possibility to extend their life time Relays It was observed that the relays which apply the reference voltage (analog) to the regulation circuit were with poor contact after many years operating It was necessary to substitute all of them Moreover, it was connected 2 switches of the relay in parallel Breakers After many years operating, breakers from Fael brand started to present problems, turning off and no more resetting They were substituted by Siemens breakers and no more failures happened Ultrafast fuses It was observed that after grid faults, the ultrafast fuses from Siemens (Sitor model) in the PS input used to fail some days later The reason was the fusing of some of their internal wires increasing the current in the remainings

28. OUTLINE INTRODUCTION MAINTENANCE STRATEGY OVERVIEW OF LNLS POWER SUPPLY SYSTEM EXAMPLES OF CORRECTIVE MAINTENANCE CONCLUSIONS

29. 5. CONCLUSIONS The preventive and corrective maintenance of the PS at LNLS have kept their reliability enough for the synchrotron source operation However, it was observed that some parts and components can be starting to show problems due to the aging, after more than 17 years of operation It is expected that UVX operate during 8 more years, then the investments in the PS improvements must take this in account Many lessons learned with UVX PS concerning to maintenance are been considered in the Sirius PS designing

30. QUESTIONS?THANK YOU!!!