EMC applied to railways

Goals

formation-objectifs-seointro EMC applied to railways :

- Learn how to identify EMC risks for a system or installation
- Be able to identify the main sources of interference
- Know how to recognise and understand the coupling mechanisms involved
- Master the appropriate protection methods, their industrial implementation and verify their effectiveness
- Be able to take into account regulatory requirements related to human exposure to electromagnetic fields
- Master the risks of coexistence of two HF communication systems

Program

Introduction
4,000 years of electricity
Electromagnetic compatibility
Interference: causes and effects
EMC terminology
Compatibility margin
Disturbance levels
EMC analysis method
Reminder on the use of decibels
Correspondence table
Why use frequency representation?
Time-frequency conversion
Propagation of electromagnetic fields
Spectral density of a pulse
Spectral envelope of repetitive pulses
Railway EMC - Harmonised standards
Emission orders of magnitude - Railway sector
Immunity orders of magnitude - Railway sector

Coupling by conduction
Common mode / Differential mode
Mains disturbances
The two common modes
Coupling via common impedance in atable
Coupling by common impedance on a board
Impedance of conductors (cylindrical wire and track)
Impedance of cylindrical conductors
Ground connections for equipment
Impedance of aEquipotentiality of the ground Reducing impedance through meshing Capacitive coupling between board and ground Total capacitance between board and ground plane>Mechanical mass / electrical mass
Connection of 0 V to the chassis
Differential mode crosstalk
Attenuation by twisting
Simple measurement of the reducing effect of a pair
Common mode crosstalk
Crosstalk reduction via ground plane
Use of electrostatic screens
Floating 0V: mechanical arrangements
Case of a train sound system
Summary of conducted disturbances

Radiation coupling
What is a field?
Coupling between E and H fields
Wave impedance as a function of distance
Radiation from a Hertz doublet
Radiation from a magnetic doublet
Near field/far field
" magnetic field à loop »
Calculation of loop voltage
Example of susceptibility of an audio system
Twisting of conductors
Example of induced voltage in differential mode
Special case of pulsed magnetic field
Summary of loop field problems
‘Electric field to cable’ couplingField propagation
Antenna current
Example of induced current
Field reduction by ground plane
Summary of wire field problems

Mastery of two HF communication systems
The five types of interference between transmitter and receiver
Different cases of interference or disturbances
EMC and spectrum sharing between services
Intermodulation in the reception chain
Calculation of intermodulation products
Intermodulation components: classification
Case study with the two systems TETRA and GSRM

Switching circuits
Static converters
Common mode of a switching power supply
Calculation of common mode
Common mode filtering
Common mode from input to output
The three cases of common mode from input to output
Reduction of common mode from input to output
Differential mode in switching power supplies
Impedance of a chemical capacitor
Implementation of chemical capacitors
Calculation of differential mode
Differential mode filtering
Mains power filter
Rectifier diode coverage
Reduction of loop area
Summary of switching problems

Power supply
Power supply quality issues
Breakdown of a current into harmonics
Mains voltage waveform distortion
Harmonic filter
Resonance of compensation capacitors
Overvoltage at relay cut-off
Clipping solution: Diode in parallel
Clamping solution: Resistor in parallel
Clamping solution: Varistor in parallel

Design, wiring and filtering rules
Principle of the reducing effect
Simple measurement of thethe reduction effect of a coaxial cable
Verification of the reduction effect of a coaxial cable
Common mode rejection by cabling
New rules of theart
BF common mode isolation components
BF protection by differential bonding
Grounding of transformer screens
Envelope detection of optocouplers
Wiring of very low-level sensors
Connection of screens at both ends
Termination of shielding
Avoid screw terminals!
Example of implementation
Connection of shielded connectors
Reducing effect of cable routes
Use of cable routesCable tray in wall crossings
Different reduction effects
Signal classification - Standard NF EN 50343
Cabling rules - Standard NF EN 50343
Advantages of optical fibres
Different structures of mains filters
The 3 rules for installing filters
Examples of filters,
Common mode filtering at the
Benefits of a local ground plane
Filter layout and routing
Common mode chokes
Ferrite core impedance
Acquisition of charges by a conductor
Teaching method: demonstration of the acquisition of charge by a conductor using a static field meter (field mill)
Triboelectric series
Continuous-continuous transformer
Potentials on floor coverings
Direct personal discharges
Typical direct discharges
Typical indirect discharges
Destruction of an IC by handling
Some typical values in electrostatics
Component degradation
Energy and power of a discharge
Standard NF EN 61340-5-1
ESD control programme
ESD protection: standard references
Use of materials (according to AEMC)
NF EN 61340-5-1: Summary table
Control of antistatic precautions: wrist straps, heel pads
Typical installation of an EPA
Access control in antistatic areas

Human risks
NF EN 50500: Human exposure in the railway sector
Exposure level - Electric field LF
Exposure level - Magnetic field LF
Exposure level - Electric field HF
Example of magnetic field LF emitted by a railway substation