Thermal conditions during prequalification testing in HVDC cable systems mimicking reality by a sandbox

Abstract

The behavior of a prefabricated joint buried in a sandbox, in order to mimic real installation under PQ test conditions has been investigated. Simulations, in combination with measurements, show that the thermal behavior of the cable and the joint in the sandbox is strongly dependent on the specific test blocks within a PQ test. It is demonstrated that such modifications pose an unnatural risk to the test circuit, which can jeopardize the positive outcome of a qualification test, by driving the system out of requirements. Moreover, this specific correction does not reflect “realistic” burial conditions. Further circuit set-up modifications, compared to a common lab test set-up, are discussed and potential thermal impact during PQ testing is discussed. It is concluded that standard recommendations are well chosen and should be followed.