REO provides innovative DC choke for use on Berlins Metro

The unveiling of the new Stadler subway series JK marks a significant step in developing Berlin’s rail network. The existing rolling stock is over three decades old, and the new train represents a leap into a new era of technology.

The initial test cars will be trialled using the Berlin metro network in January 2024 before being put into regular passenger service starting in late summer 2024. Introducing this new subway series represents a significant advancement in rail technology and lays the groundwork for further innovations in the future.

While there are hardly any noticeable external differences, the JK series impresses with many innovations from a passenger’s point of view. Improved doorways and enhanced customer information areas give a more spacious feel and generous standing room. New vertical handrails render ceiling bars unnecessary, and unique bent handrails facilitate easier passage for wheelchair users. Additionally, space-saving screens and integrated size indicators on signs indicating spaces for disabled persons are part of the modernized interior.

On the power side, the collaboration between REO TPM and ABB drives helped accelerate significant technological advancements. A special DC network choke was developed to be integrated into the new subway carriages. As an essential drive train component, this choke protects against circuit-induced current spikes and reduces harmful network feedback.

The carriages are designed to operate at a maximum speed of 70 km/hr, so the chokes must be robust and able to withstand significant levels of shock and vibration and provide excellent EMC performance. A special ferromagnetic enclosure was designed to minimize electromagnetic interference and provide the required durability levels for this demanding application, enhancing the subway’s safety and reliability.

In addition, the units are specially coated to improve insulation and reduce creepage and clearance distances, allowing the physical size and weight to be reduced, an essential factor in modern railways.

If you would like to find out more about REO’s capabilities in the field of chokes, please visit



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