EMC Investigation

Unusual event

Sometimes strange events occur, often with serious impact.  Aitken & Partners specialises in identifying and correcting these problems.
 
Extensive experience in electromagnetic compatibility is the basis of a systematic approach to investigation.  We couple this with an extensive array of test equipment, antennas and probes.

Problems we have investigated include ECP crosstalk, RF tag reading faults, induction from locomotive traction systems and communication system performance degradation due to antenna system design and desensitisation.

Measuring earth current on axle

Railway EMC

Aitken & Partners are consulting engineers who specialise in electromagnetic compatibility engineering in the railway environment. With over 30 years of experience, covering most Australian railways, we are very familiar with the environment.

The principal, John Aitken, is a qualified and experienced engineer with specialist training in electromagnetic compatibility engineering (EMC). He is the author of the Australian Standard for train radio communications, AS7660 and has written a number of technical papers associated with rail systems. John is a past chairman of the Institution of Railway Signal Engineers Australasia (IRSE) and has been a member of the IRSE international council. He has attended specialist training in EMC in the USA and Australia and is a member of the IEEE EMC Society.

Aitken & Partners have extensive experience in broadcasting, television and electronic engineering. The diversity of systems and issues encountered in these disciplines has contributed to our understanding of the traction environment.

We are familiar with the requirements of EN50121, the international standard for EMC in railway applications and have performed analysis and tests in accordance with this standard. We have worked with the ATCS specifications for EMC and have designed and tested in accordance with those specifications.

Equipment

Aitken & Partners has a full set of measuring antennas for the frequency range 9 kHz to 6 GHz. These antennas include a rod and loop for the lower frequencies, biconical antennas, log-periodic antennas and a ridged horn for the highest frequencies.

We have a Rohde & Schwarz FSL6 spectrum analyser and specialist equipment for digital television and AM radio measurement.

This set of equipment enables us to perform radiated emissions testing in accordance with a number of standards, including EN50121 - Railway Applications - Electromagnetic Compatibility.

For lower frequency work we have a Narda EHP-50D electric and magnetic isotropic field analyser, covering the frequency range 5 Hz to 100 kHz. This instrument is suitable for both real-time and stand-alone continuous data acquisition.

Experience

Railway EMC and Electrification Projects

The more successful train radio projects start with an EMC analysis. Aitken & Partners developed coverage guidelines for RailCorp electrified track through analysis and then testing of the noise contribution of the traction system. That work on DC systems established the standard for RailCorp and was followed by a similar exercise for Perth Electrification, this time for an AC system.

Desensitisation and intermodulation are important aspects of mobile communications that are often ignored. With the restricted real estate available on a locomotive careful analysis and antenna placement is essential. Aitken & Partners did this for Teknis International Railroad Systems, when we analysed the electromagnetic compatibility of the several voice and data radio systems to be installed on Australian National locomotives. This included selection of antenna locations and measurement of the coupling between the antennas. We have performed similar work for Westrail, Perth Electric, RailCorp and Pacific National.

New locomotives designs require extensive EMC analysis to ensure that each of the components and subsystems will work together, forming a functional and compliant locomotive. Aitken & Partners are responsible for supervising the EMC aspects of a new 4 MW diesel electric locomotive, including preparation of an EMC study, EMC management plan, subsystem integration and final proof testing of the locomotive.

Aitken & Partners have prepared an EMC plan for a railway operator's new freight operations. This work has required desktop analysis of sub systems and then field testing of radiation from the trains.
Much EMC work relates to investigation of problems. One of our more interesting projects was investigating EMC problems with electro-pneumatic braking systems. For this project we worked with Andrew Blakeley-Smith and Associates. The investigation revealed layers of interacting problems, most caused by equipment that complied with the relevant standards. Put together as a railway system it did not comply and problems arose. The root causes of the problems were identified, solutions proposed and the problems were overcome.

Railway electrification projects introduce large electric and magnetic fields close to the traction system and generate wide-band electromagnetic noise in the vicinity of the railway. Aitken & Partners have been commissioned by the South Australian DPTI to provide EMC advice for the Adelaide electrification project. This has included assessment of the effects of the traction systems on a convention centre immediately above the catenary system at the central railway station.

 

Effects of Structures

Other EMC related projects have included pre-construction and post-construction surveys for a number of wind farms. The EMC surveys are usually a condition imposed in the development approval by the regulatory agency. Our surveys quantify the extent of interference with television reception that may occur when the wind farm is built and provide advice on mitigation strategies. The post-construction surveys compare the reception quality with pre-construction measurements, providing an objective basis for mitigation work.

Large buildings can affect television reception: we were engaged by the developer to assess the impact of the Rockdale Gardens development on television reception in the Rockdale area. This was followed by a remediation plan and technical supervision of the remediation work at 59 properties.
Aitken & Partners analysed the impact of a proposed major television and FM broadcasting tower on mobile radio facilities at Mt Lofty for the Electricity Trust of South Australia.

Electronic Design

Electronic design investigations have included investigation of electrostatic fields in a product, evaluation of their impact and proposal of a set of solutions. We were responsible for the design and submission for CE testing of a medical electronic device for Nascor.

Interference

Interference analysis and investigation projects have been performed for Telstra, Standards Australia, equipment manufacturers and the Sydney casino.

Site Proof Tests

Site proof tests are required for some data centres and more sensitive electronic systems. They are often used for selection of satellite earth station locations and receiving systems. We performed site proof measurements at several locations while assessing a satellite earth station location for Optus. We measured of electromagnetic fields at two potential computer centre locations in Perth and a dealing room site at The Rocks, Sydney. This was a sensitive location as there is a naval base nearby that at times radiated substantial energy.

Westpac engaged our services for measurement of electromagnetic fields at a number of potential computer centre sites. Detailed measurements at the selected site, advice to the building architects and preparation of a specification for a large screened room followed.