Traction and rectifier MV transformers for traction substations

Description

The task of a traction transformer is to convert electrical energy stably and safely between the distribution network and the power supply equipment of rolling stock. Traction load changes sharply, so the units are designed for strong load fluctuations, high currents and the dynamic changes in power consumption typical of traction systems. They work in configurations typical of traction substations, and the design allows them to be integrated with rectifier units and energy recovery systems.

Like the other MV transformers of the plant in Lubliniec (Poland), the traction units are dry-type, with vacuum pressure impregnation (VPI) of the windings. This impregnation gives a low partial discharge level and resistance to moisture and contamination. A robust design, high dielectric strength of the insulation and well-considered cooling support continuous operation even in difficult climatic and temperature conditions. The plant's MV transformer line covers voltages up to 24 kV.

As an example of an implementation, the manufacturer cites a 1,200 kVA rectifier transformer for a 12-pulse rectifier that feeds a tram network from a 15.75 kV grid. There is no separate catalogue card with a parameter table for traction transformers, and the rated data of a specific unit is set in the enquiry sheet. It states the supply network voltage, the rating and the scheme of the rectifier the transformer will work with. Versions with parameters outside the standard range are possible by prior agreement.

The manufacturer names several advantages of the series. Energy is transmitted to the traction network with minimal losses. Stable operation and overload resistance increase system safety. High efficiency and low no-load and load losses reduce operating costs. A long service life meets the requirements of transport infrastructure, and product quality is confirmed by certificates.

The transformer can be retrofitted with temperature sensors, insulation condition monitoring systems and enclosures with a higher protection degree. The sensors and insulation monitoring give substation personnel data on the thermal state and the insulation state of the unit. Outside traction substations, the units are used to supply urban infrastructure and auxiliary equipment of traction systems. For Ukrainian railways and urban electric transport, they are considered as a replacement for converter transformers of DC traction substations, and selection is based on the enquiry sheet.

Technical specifications

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