1. A common 400 Hz AC Power Supply Distribution System for CMS FEE. Authors C. Rivetta– Fermilab. F. Arteche, F. Szoncso, - CERN

2. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 2 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 OUTLINE  1- System Description  2- Design - General Guidelines  3- Voltage Disturbances –Steady State - Voltage Regulation –Steady State - Harmonics –Transient Voltage Disturbances –Voltage Sources  4- Over current protections  5- Grounding  6- Conclusions

3. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 3 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 1.SYSTEM DESCRIPTION  M-Gs convert 50 Hz mains to 400 Hz - 208 V - 3 phase  Sub-detectors will be supplied by individual units.  3-phase distribution system between counting room and periphery of the detector.  Sub-detectors have proposed 2 different conversion units: –Simple 3-phase rectifiers-filters & LV regulators –AC/DC conversion to 48V DC & DC-DC converters  3 phase rectifiers-filters & DC-DC converters will operate under neutron radiation and fringe magnetic fields.

4. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 4 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 1.SYSTEM DESCRIPTION

5. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 5 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 2.DESIGN - GENERAL GUIDELINES  Power quality distribution –Amplitude variations  Several forms - Duration: sub-cycle to steady state –Waveform variations  Distortion –Unbalances  No single-phase loads –Frequency variations  Characterisation of loads -Characterisation of the environment. IEEE Std 1100 - 1992

6. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 6 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 3.1 STEADY STATE VOLTAGE DISTURBANCE - VOLTAGE REGULATION  Distribution cable impedance much higher than 50 / 60 Hz –Non-ferrous conduits. –400Hz especial cables. –Impedance drops up to AWG #1 / 54mm 2  Voltage drop in transformers and generators. –Generator can operate with closed loop voltage regulators.

7. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 7 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 3.1 STEADY STATE VOLTAGE DISTURBANCE VOLTAGE REGULATION - EXAMPLE Group of loads AWG 6 / 13,3mm 2 AWG 8 8,36mm 2 5mts 100mts 20mts P1 P2 +5% P2Load +5% Vn -5% No load Full load Gen P1 Vn -5% No load Full load P2Load

8. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 8 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 3.2 STEADY STATE VOLTAGE DISTURBANCE HARMONIC DISTORTION  All CMS loads connected to the 400 Hz. system are non linear. –Generate harmonics current.  Harmonics currents imply: –Over-rating. –Voltage distortion  400 Hz. harmonic effects are more severe than 50/60 Hz.  Voltage generators and static converters can produce good quality sine waves - THD 3%  Current harmonics can be reduced by filtering /compensation or imposing restrictions to the load harmonics generation.

9. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 9 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 3.2 STEADY STATE VOLTAGE DISTURBANCE HARMONIC DISTORTION  Loads are qualified by harmonic indices –Strongly correlated to the severity of the harmonics effects.  Recommended harmonics indices are : –Individual and total voltage distortion. –Individual and total current distortion.  Standards define limits based: –On loads size. –Characteristics of load groups.  Examples –Dedicated system:  Maximum individual frequency voltage harmonic = 2.5 / 3 %  Maximum individual frequency current harmonic - Lower 4 %

10. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 10 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 3.2 STEADY STATE VOLTAGE DISTURBANCE HARMONIC DISTORTION - Example - A I1 I2

11. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 11 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 3.2 STEADY STATE VOLTAGE DISTURBANCE HARMONIC DISTORTION - Example A  In : one power converter  Vn: 15 power converters /100mts AWG#8 - 13.3mm 2

12. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 12 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 3.2 STEADY STATE VOLTAGE DISTURBANCE HARMONIC DISTORTION - Example B

13. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 13 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 3.2 STEADY STATE VOLTAGE DISTURBANCE HARMONIC DISTORTION - Example B  In : one power converter  Vn: 15 power converters /100mts AWG#8 - 13.3mm 2

14. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 14 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 3.3 TRANSIENT VOLTAGE DISTURBANCE  Load related changes & switching events cause disturbances between equipment and power source –Step loads. –In-rush currents.  Origin: Start-up transformers & Rectifiers with capacitive filters –Faults currents.  Origin: Short-circuit faults.  Long duration: Several cycles of fundamental wave form.  Impact : –Complete loss of AC power. –Short term voltage variation. –Data up-set.  Design criteria –Reduce the transient energy ( Start-up systems, load sectioning..)

15. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 15 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 3.4 VOLTAGE SURGES  Switching surges –Originated by fuses, circuit breakers and switches –Wave form - Fast rise time followed by damped oscillation  Sub-cycle voltage transients  Impact depends on the severity of the transient and equipment susceptibility. –Signal data disruption –Gradual hardware stress –Immediate hardware destruction  Design criteria –Transients voltage supressors in distribution system and equipment

16. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 16 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 4 OVER CURRENT PROTECTIONS  Appropriated co-ordination of current protections –Rating & Clearing Timing  50 / 60 Hz components has to be properly de- rated for 400Hz applications –Fuses are not appreciably affected –Thermal-Magnetic & Magnetic circuit breakers are affected  Magnetic circuit breakers & switchers must be excluded from areas where exist magnetic field

17. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 17 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 5 GROUNDING  Grounding is essential for safe and satisfactory performance of the complete system.  Characteristics –Low impedance path for the return of fault currents. –Low potential difference between expose metal parts to avoid personal hazards. –Over-voltage control on sensitive electronics. –Should be compatible with the system performance and noise, without compromising safety  The grounding of the distribution system will follow the general grounding rules imposed to CMS experiment

18. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 18 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 5 GROUNDING SENSITIVE LOAD

19. A common 400 Hz AC Power Supply Distribution System for CMS FEE.– 19 / 19 8 th Workshop on Electronics for LHC Experiments COLMAR - France, 9-13 September 2002 6 CONCLUSIONS  Design considerations for quality power distribution of the CMS 400Hz distribution has been presented.  Further considerations –Better understanding of the impact of environment conditions on protections, load performance, etc. –Definition of final system topology.  Definition of specifications based on voltage quality wave form and system reliability –System design specifications –Load specifications (Sub-detectors)