A common 400 Hz AC Power Supply Distribution
A common 400 Hz AC Power Supply Distribution System for CMS FEE. Authors C. Rivetta– Fermilab. F. Arteche , F. Szoncso, - CERN
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 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
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 48 V DC & DC-DC converters 3 phase rectifiers-filters & DC-DC converters will operate under neutron radiation and fringe magnetic fields. 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 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
2. DESIGN - GENERAL GUIDELINES Power quality distribution IEEE Std 1100 - 1992 – 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. 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
3. 1 STEADY STATE VOLTAGE DISTURBANCE - VOLTAGE REGULATION Distribution cable impedance much higher than 50 / 60 Hz – Non-ferrous conduits. – 400 Hz especial cables. – Impedance drops up to AWG #1 / 54 mm 2 Voltage drop in transformers and generators. – Generator can operate with closed loop voltage regulators. 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 - EXAMPLE Group of loads AWG 8 P 1 5 mts AWG 6 / 13, 3 mm 2 8, 36 mm 2 P 2 20 mts 100 mts No load +5% Vn -5% Full load Gen A common 400 Hz AC Power Supply Distribution System for CMS FEE. – 7 / 19 P 1 P 2 Load 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. 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 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 % 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 - Example - A I 1 A common 400 Hz AC Power Supply Distribution System for CMS FEE. – 10 / 19 I 2 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 /100 mts AWG#8 - 13. 3 mm 2 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 B 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 In : one power converter Vn: 15 power converters /100 mts AWG#8 - 13. 3 mm 2 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. 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. . ) 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. 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 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
4 OVER CURRENT PROTECTIONS Appropriated co-ordination of current protections – Rating & Clearing Timing 50 / 60 Hz components has to be properly derated for 400 Hz 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 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
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 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 SENSITIVE LOAD 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
6 CONCLUSIONS Design considerations for quality power distribution of the CMS 400 Hz 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) 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
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