1 Scope
This Technical Specification covers gas and liquid actuated (Buchholz) relays for
liquid immersed transformers and reactors with conservator for rail vehicles.
The device is intended to detect
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• gas release from the unit to be protected,
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• cooling liquid surge from the protected unit to the conservator,
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• complete loss of the cooling liquid in the conservator.
This Technical Specification gives consideration to both technical and normative requirements
of the railway environment and restricts the variety in particular provided by the
industry-wide standard EN 50216‑2. It determines requirements and tests enabling the interchangeability of Buchholz
relays by defining the following types of interfaces:
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• mechanical interface, e.g. flanges for pipe connection, dimensions;
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• electrical interface, e.g. supply voltage for making and breaking capability;
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• functional interface, e.g. protective operational behaviour.
It is not applicable to flameproof relays. Different liquids may be used, which are
typically used for both cooling and insulating.
Furthermore, operating conditions are described.