Download ELECTROMAGNETIC TOPOLOGY

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
8th 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.
A common 400 Hz AC Power Supply
Distribution System for CMS FEE.– 3 / 19
8th Workshop on Electronics for LHC Experiments
COLMAR - France, 9-13 September 2002
1.SYSTEM DESCRIPTION
4 0 0 H z D istrib u tio n at C M S
• T o p o lo g y – B ased o n H C A L /E M U sy stem s
 -Y o
D istr.P an el
MG
A C -D C
2 0 8 V /4 0 0 H z
A rea 2
A C -D C
A rea 3
A C -D C
1 0 -2 0 m ts.
1 5 0 m ts.
A rea 1
A common 400 Hz AC Power Supply
Distribution System for CMS FEE.– 4 / 19
8th 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
8th 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 / 54mm2
 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
8th 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
P1
5mts
AWG 6 / 13,3mm2
8,36mm2
P2
20mts
100mts
No load
+5%
Vn
-5%
Full load
Gen
A common 400 Hz AC Power Supply
Distribution System for CMS FEE.– 7 / 19
P1
P2
Load
8th 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
8th 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
8th Workshop on Electronics for LHC Experiments
COLMAR - France, 9-13 September 2002
3.2 STEADY STATE VOLTAGE DISTURBANCE
HARMONIC DISTORTION - Example - A
I1
A common 400 Hz AC Power Supply
Distribution System for CMS FEE.– 10 / 19
I2
8th 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 - 13.3mm2
A common 400 Hz AC Power Supply
Distribution System for CMS FEE.– 11 / 19
8th 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
8th 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 - 13.3mm2
A common 400 Hz AC Power Supply
Distribution System for CMS FEE.– 13 / 19
8th 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
8th 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
8th 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 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
A common 400 Hz AC Power Supply
Distribution System for CMS FEE.– 16 / 19
8th 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
8th 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
8th 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)
A common 400 Hz AC Power Supply
Distribution System for CMS FEE.– 19 / 19
8th Workshop on Electronics for LHC Experiments
COLMAR - France, 9-13 September 2002