Lars Buhrkall

Freelance Electrical Engineer

Electrical Drives, Traction Systems, and Electromagnetic Compatibility

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This section provides information about some of the technical and procedural problems that have cost too much money in too many projects.

The 4 big challenges of modern electric railways are:

1. Increased system complexity. 50 years ago, Karl Sachs could describe in just 3 volumes of "Elektrische Triebfahrzeuge" everything one needed to know to design an electric locomotive. Today, 3 volumes are not enough to document just a single circuit board in the train control system. It is no longer possible for a single individual to have the full overview of the behaviour of a locomotive at all possible operation conditions.

2. Signal interference and EMC. The 3-phase inverters of modern AC drives are inherently capable of producing interference currents at virtually any signal frequency. Even if the normal interference levels are low, they can increase dramatically at fault conditions.

3. Electrical system instability. The 4-quadrant line converter of an AC-AC locomotive is an active device, not only at the line voltage fundamental but throughout a wide frequency range. Complete shut-downs of railway systems due to system instability caused by modern high-power locomotives have already been observed.

4. Acceptance procedures and project responsibilities. The new market situation with at least 4 players in the game (the multinational industry, the train operator, the infrastructure owner, and the approving authority or inspectorate) has had a mushrooming effect on the acceptance procedures in most European countries.


(I'm still working on the material for this section. Meanwhile, please take a look at the downloads page - there you will find more information. LB)


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Latest update: 06.09.2014