Electromagnetic Compatibility Test for CMS Experiment.

1
Electromagnetic Compatibility Test for CMS
Experiment.

• Authors
• C. Rivetta Fermilab
• F. Arteche , F. Szoncso, - CERN

2
OUTLINE

• 1.Introduction
• 2. Common Impedance
• LISN.
• CDNs.
• 3.Emission Test
• Harmonics.
• RF conducted emission test.
• 4.Immunity Test
• RF conducted noise immunity test.
• Slow transients - Surge immunity test.
• Fast transients - Burst immunity test.
• Voltage dips and short voltage interruptions
  immunity test
• 5.Conclusions

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1.INTRODUCTION

• EMC phenomena are present in CMS
• Noise generated by DC-DC converters
• Common mode Differential mode
• Transients
• Over-voltages
• Induced via magnetic fields
• Load changes
• Switching
• Voltage variations
• Harmonics
• It is important to measure control them
• Goal of these tests
• Get the levels of emission and immunity
• Identify possible EMC problems.

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1.INTRODUCTION

• Generic, Basic and military Standards Aerospace
  rules.
• There are a lot of standards
• For practical reasons we only consider some of
  them
• Emissions test
• RF conducted noise (based EN-55011-22 //
  MIL-STD-461// IEEE Std 1515)
• CM DM ( high and low frequency)
• Harmonics (based EN- 61000-3)
• Special for 400 Hz power supply distribution
  system (very low)
• Immunity test
• Immunity to RF conducted noise (based
  EN-61000-4-6)
• Electrical fast transient burst immunity test
  (based EN-61000-4-4).
• Surge immunity test- Over-voltage (based
  EN-61000-4-5).
• Voltage dips, short interruptions and voltage
  variations immunity test (based EN-61000-4-11).

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2. COMMON IMPEDANCE LISN CDNs

• Two kinds of common impedance
• Line Impedance Stabilisation Network (LISN)
• Coupling De-coupling Network (CDNs)

• CDNs
• Protect auxiliary equipment
• Values specified by the standards

• LISN
• Present stable a well defined impedance
• Standardise the measurements of test
• Values estimated from power cables
• HF - Characteristic Impedance (CM DM )
• Different from commercial LISN
• Couple EUT - Measuring equipment.
• Standardise the measurement to 50 Ohms

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2. COMMON IMPEDANCE LISN CDNs

• LISN HCAL Sub-System

Zcm 13 Ohms
Zdm 42 Ohms
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3.EMISION TEST - Harmonics

• Effects by pulling the current from power main
  for only a part of the cycle
• Typically rectifiers ( we have 400 Hz power
  distribution)
• Implications
• Quality power distribution.
• Power supply distribution over-design
• Power transformers over-stress
• Equipment overheat
• Oriented to the 400 Hz PS distribution
• AC-Dc converters
• Transformers
• Limits of harmonics based on international
  standards studies.

Power supply unit
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3.EMISION TEST - RF conducted noise

• Goal of test control the conducted emission level
• Power Supplies FEE
• Frequency Range 9 kHz - 50 MHz
• Conducted emissions Propagation
• Common Mode
• Group of conductors and ground or other
  conductors.
• Differential Mode
• Conductor pairs (Negative-Positive or
  Phase-Neutral)
• Abundant energy exchange between modes CM - DM
  conversion
• System topology as close as possible to final one
• Common impedance LISN
• Equipment used
• Current probes Spectrum Analyser

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3.EMISION TEST - RF conducted noise

• Power Supply

• FEE

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4.EMISION TEST - RF conducted noise
EN-55022

• Test Results Power Supplies
• Input
• Results refereed to 50 Ohm to compare them with
  the standards
• We used EN - 55022 B
• Output
• There is no standards so we need to generate them
• From this values and the values from Immunity
  test
• FEE
• Input
• Results refereed to 50 Ohm to compare them with
  the standards

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4.IMMUNITY TEST- RF conducted noise

• Electromagnetic immunity is the ability,of a
  device equipment or system to perform without
  degradation in presence of electromagnetic
  disturbances
• Goal of these tests
• Immunity level of FEE and PS to conducted
  disturbances.
• Injection of conducted noise to the FEE
• Common impedance - LISN
• The idea is inject signal and measure pedestal
• Identify frequency areas where the pedestal is
  not valid
• This test will define sensible areas of the FEE
• Injection via current probes
• It is recommended to Voltage Current

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4.IMMUNITY TEST - RF conducted noise

• Three different set-ups
• DM configuration
• 9 kHz / 14 kHz up to 100 MHz
• CM at HF configuration
• 10 kHz up to 100 MHz
• CM at LF configuration
• (A few hertz up to 10 kHz)
• The value of the amplitude of the signal depends
  on the sensitivity of the FEE.
• This test is complementary of Conducted emission
  TEST

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4.IMMUNITY TEST - RF conducted noise - Example

• CM

I1
ICM
12.05 µA
12 V
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4.IMMUNITY TEST - RF conducted noise - Example

• I1

• CM

0.41mA
IDM
ICM
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4.IMMUNITY TEST - Surge immunity Test

• The goal of test - Determinate the equipment
  susceptibility to damage by over-voltage
  generated by
• Load changes /Short Circuits /Faults to earth
• Common Impedance LISN CDNs to protect auxiliary
  equipment
• Coupling network will be used to inject the
  transient
• 9 µf 10 Ohms or 18 µf - Depends on the Test
• Pulse Characteristic
• Voltage O.Circuit 1.2/50 µs.
• Current S.Circuit 8/20 µs
• A Zenner / Trans-absorb protect EUT from this
  emission

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4.IMMUNITY TEST - Surge immunity Test

• The amplitude of the signal
• Standards
• Electrical environment
• 5 Different Class
• 0.5 , 1kV , 2 kV, 4 kV
• For CMS values
• Counting Room - Detector
• Class 3 or 4 - (1kV-4 kV)
• Balconies - Detector
• Not clear
• Test simulation for 3 different amplitudes
• 1 kV , 500 V , 100 V
• Line - Line

Trans-absorb
Filter
FEE
CDNs
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4.IMMUNITY TEST - Surge immunity Test

• It is difficult to find a device to dissipate
  this power and clamp the voltage within maximum
  values valid for the FEE.
• Level selection
• High level
• Increase cost or could not have any technical
  solution
• Low level
• Increase risk of failure by over-voltage
• Final selection based on
• Preliminary studies
• Reliability.
• Cost
• Risk

83 V
45 V
15 V
17 kW
4.5 kW
0.3 kW
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4.IMMUNITY TEST - Burst immunity Test

• The goal of test
• Fix the susceptibility to damage by over-voltage
  generated by switching transients.
• Common Impedance LISN CDNs to protect auxiliary
  equipment.
• Coupling network will be used to inject the fast
  transient - 33 nf.
• Pulse Characteristic
• Double exponential 5ns/50 ns.
• Burst duration 15 ms / 300 ms
• (1 minute).
• Spectra content of signal HF.
• Layout very important.
• Coupling of burst depends strongly from parasitic
  capacitance.

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4.IMMUNITY TEST - Burst immunity Test

• Class is not defined yet.
• Not very important
• A simple Capacitor protects to FEE from this
  emission
• Test simulation
• 3 different RF capacitors
• 5nf, 500nf, 1000nf
• Line - Ground
• Amplitude
• Class 3 - 2 KV.

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4.IMMUNITY TEST - Voltage dips immunity Test

• Noise source
• Faults in the networks
• Sudden large change of load
• Test on FEE
• Short interruptions Voltage variations
• Test on Power Supplies
• Short interruptions Voltage variations
• Voltage dips
• Common impedance LISN
• Test level
• Standards
• Voltage dips
• ( 0-40-70) V nominal - Voltage variations
• (0 -40 ) V nominal. -
• For us under study

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5. CONCLUSIONS

• EMC phenomena is present in CMS
• It is important to measure and control them
• EMC tests are based on standards and aerospace
  industry .
• EMC test will be focus on conducted noise
• Immunity and emissions test
• Only a few test will be considered due to
  practical reasons
• Test levels has not fixed yet
• It has a big influence in the elections of
  filters protections
• It will depend on
• Technical studies
• Reliability
• Cost
• Risk