16. Induction predicting simulator applicable to data transmission frequency bands

Induction voltage and current in trackside telecommunication lines are caused by feeder voltage and ground return current (Figure 1). As a means to prevent problems such as electrocution and interference with telecommunication lines, countermeasures of equipment based on results of prediction calculations have been implemented.

However, existing methods for calculating induction predictions could only be used in audio frequency bands. Also these methods modified calculated values by considering influence from cable structures and iron rebars in civil structures, which means that the calculated values were generous approximations of induction occurrence.

Therefore, a new induction predicting simulator was developed, which is applicable to high frequency band above the audio frequency and capable of considering multiple conductors in structures.

The simulator uses a new method where parameters are calculated by suitable approximation equations which take into account the ground effect and the skin effect of conductors, while the model is split into smaller sections as the frequency range increases, extending the frequency range from the audio frequency band of 4 kHz up to the data transmission band of 1 MHz (Figure 2).

While the new simulator removes the limit on the number of longitudinal conductors which was several dozen in old simulators, its calculation speed is also faster by using parallel processing which is used for models with very large calculation loads. Therefore, installation conditions can be considered in great detail, and the prediction accuracy was increased by about 10% (Figure3).

The simulator will make it possible to quantitatively evaluate the effectiveness of anti-induction countermeasures to reduce induced voltage and induced current on telecommunications lines, when upgrading or installing new power, or wire-based telecommunications equipment. The simulator can also be used for predicting voltage and current induction in rails.