Customer: Régie Autonome des Transports Parisiens (RATP)

Location: France

Application: Trackside Transformers

Rating: 3.3MVA – 5.5MVA

Date: 2008 – present

RATP is a state owned organisation in France that operates the Paris public transport network and within the Île-de-France region they carry around 3 billion passengers per year. RATP are responsible for the Paris Métro underground as well as trams, buses and part of the RER suburban rail network. They have an extensive electrified network requiring a large number of trackside and auxiliary transformers.

RATP had been using CG Power’s SLIM transformers on their network. These SLIM units were already more compact than normal transformers, running at higher operating temperatures, through the use of NOMEX solid insulation, in combination with silicone liquid. RATP saw the advantage in this technology as it allows them to achieve higher reliability and handle bigger, more frequent overloads in transformers that will fit into the confined space of trackside substations. A secondary advantage of using the high temperature SLIM technology was that no forced cooling is required. This saves energy, reduces maintenance and lowers noise levels. However this solution was not environmentally friendly since silicone is not biodegradable and RATP wanted to improve this situation.

To provide a more environmentally sound transformer, through collaboration between CG Power and M&I Materials, the Bio-SLIM transformer was developed using MIDEL 7131 synthetic ester as the dielectric fluid, instead of silicone. In addition to being more environmentally friendly, by using MIDEL 7131 the design could be improved further, as MIDEL has better cooling and electrical properties than silicone liquid. This provided even more compact transformers and allowed CG Power to extend the SLIM transformer range into higher voltage ratings, above 36kV.

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