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Performance Lab Tests

Groundbreaking Testing Validates TP's Exceptional Performance in Transformer Protection

The most recent study of the TP was carried out by the High Power Test Station (Station d’Essais de Grande Puissance, SEGP) teams at the request of SERGI TP. Transformer Fast Depressurization Systems (TP) manufacturer sought to conduct a testing campaign of the device.

The TP is defined in the 2020 edition of the NFPA (National Fire Protection Association) Code 850 for Transformer Fast Depressurization Systems:

“A passive mechanical system designed to depressurize oil-filled equipment such as transformers, current-limiting reactors, bushing cable boxes, or load tap changers a few milliseconds after the occurrence of an electrical arc”.

The test campaign involved the generation of electric arcs inside a sealed oil-filled transformer tank. Upon arc ignition, the dynamic pressure variation generated by the gas production reaches the TP depressurization assembly (DS), expelling a mixture of oil and gas from the tank, ensuring its depressurization. EDF’s live test was also witnessed by Bureau Veritas, an independent international certification company.

A 7.5 MVA transformer had been modified for the tests purpose, it was equipped with dynamic pressure sensors (8) and static (2), temperature sensors, as well as 2 Arc Generation Devices (AGD): one located at the bottom of the transformer tank, and the other at the top. They were connected to the station busbars for producing arcs from the Arc Generation Device fuse wires. The arc voltage could be modified by adjusting the distance between the electrodes. An unprecedented assembly was carried out during 2 weeks, with pipes, an Oil and Gas Storage Tank (OGST) for gas identification and the volume measurement, control cabinets and an oil treatment plant shown in the attached pictures.

Arc currents between 10kA and 20kA with arc energies between 680kJ and 4,040kJ have been achieved.

The results of the TP tests have clearly demonstrated that the TP is extremely effective in protecting transformers against explosions and fires during arc faults, with a performance that far exceeds the expectations of a fast depressurization system compliant with NFPA Code 850.