RS Electro: Cables under water or underground, or how just one measurement revealed the cause of a damaged transformer

Swedish company Gasenzer AG specializes in the diagnostic for cables and electrical equipment. Willie Boller works there – and electrical engineer with a rich experience in the field of testing medium voltage cables. One of his business trips to the Lucerne lake under the request of a client has left him surprised. When he began his trip to the client, Willie Boller had no idea if he was just going to test the cables or if he had to localize any faults. "The only information the Gasenzer specialist had was that an explosion had occurred in the transformer at the gravel quarry substation," said the company RS Electro, a partner of the German manufacturer Baur of test equipment for cables and electrical equipment.

It turned out, it was very likely. The connected underwater cable providing power to the dredge has been twisting over and over under the water due to the position of the machine, and the added pressure has resulted in additional mechanical stress. Willie Boller, with the help of the testing equipment in his Baur van, conducted initial tests for cable isolation and echometric tests, but didn’t discover any problem areas. "However, relief came only after a test with Baur's portable viola testing device was performed, with the cable successfully withstanding a VLF test at three times the voltage U₀ for more than 30 minutes, proving that the cable was not the cause of the transformer failure. This meant that the problem could be quickly fixed and the substation put back into operation," commented RS Electro.

"Baur's portable, high-performance viola tester is available in two configurations. The standard model is used for testing cables and cable sheaths of electrical equipment and medium voltage cables up to 35 kV, including insulation testing, with the patented VLF-truesinus® technology ensuring high measurement accuracy," notes PC Electro.

Photo source: RS Electro, Baur, ©Engineer BG via Canva.com