advances in emc measurements on railways
DESCRIPTION
Advances in EMC Measurements on Railways. Origins of EMI in Railways. Difficulties With Railway EMC Measurements. (Fast) Moving EUT Large EUT Complex Radiation Propagation Mechanisms Poor Control of Measurement Environment Transient Emissions from traction motors from power supply arcing. - PowerPoint PPT PresentationTRANSCRIPT
Advances in EMC Measurements on Railways
Origins of EMI in Railways
Difficulties With Railway EMC Measurements
• (Fast) Moving EUT• Large EUT• Complex Radiation Propagation Mechanisms• Poor Control of Measurement Environment• Transient Emissions
– from traction motors– from power supply arcing
The Measurement System
• Three Spectrum Analysers giving:– constant monitoring of a chosen frequency range
• Two Further Spectrum Analysers:– to detect transient emissions (amplitude & repetition)– set to single frequency (zero span)– wide input bandwidth– two analysers allow for test site variations and
spurious radio signals
• Camera:– to record an image associated with each plot
Transient Detection
• Tuned Receiver / Spectrum Analyser– good dynamic range– readily available in EMC laboratories– good response when wide bandwidths
chosen
• Fast Sampling Oscilloscope– All signal information can be captured
instantaneously
Transient Detector 1 (350MHz)
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25 30
Time (seconds)
Rec
eive
d L
evel
(d
Bu
V)
Transient Detector 2 (360MHz)
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25 30
Time (seconds)
Rec
eive
d L
evel
(d
Bu
V)
Variations in Emissions
0
5
10
15
20
25
30
35
0.1 0.105 0.11 0.115 0.12 0.125 0.13 0.135 0.14 0.145 0.15
Frequency (MHz)
Re
ce
ive
d L
ev
el
(dB
uV
)
Vehicle 1
Vehicle 2
Vehicle 3
The System Aids In:
• Measurement of EM emissions from railway systems dynamically
• Separation of continuous and transient events– Increasingly important as digital communications
become more widespread
• Rapid assessment of rolling stock characteristics• Monitoring and assessing variations and
degradations