The occurrence of arc faults in electrical systems, e.g., in transformer substations, is an exception with a risk of personal injury and damage to switchgear and the surrounding buildings due to the thermal and mechanical effects. The arc fault involves a pressure load, which has to be taken into account in the structural design of the system. In order to estimate the pressures that occur, arc fault pressure calculations are carried out using different methods. The paper focuses on a transformer substation (a precast concrete construction) with an internal arc fault in the medium voltage switchgear. The pressures simulated before the test are compared to the values measured during the test. With the recorded electrical quantities and the pressure, the thermal transfer coefficient, which can be used for new simulations, is then determined as an essential input parameter for the pressure simulation. In addition, the effect of an absorber grille in the relief path is examined, and the pressure plots before and after this energy-dissipating element are compared. In preparation for the arc fault test, the pressure plots in the transformer substation are calculated using two different commercial programs. During the experiment, the initial pressure of an arc fault initiated in a controlled way is measured in the cable basement with piezoelectric pressure sensors. The pressure plots are compared with the values measured during the internal arc fault test. The pressure that builds up in the switching chamber (inner metal housing of the switchgear) due to the arc is measured with a piezoresistive pressure sensor. Together with the calculation of the power conversion of the arc, the thermal transfer coefficient of the switchgear is determined at the beginning. This way, an important parameter for the pressure calculation can be determined by means of space-averaging and spatially resolved pressure calculation methods. Thus, a contribution can be made to improve these methods and to bring the simulation closer to practice.
|Translated title of the contribution||Practical experience from internal arc fault testing|
|Number of pages||9|
|Journal||Elektrotechnik und Informationstechnik|
|Publication status||Published - Feb 2022|
ASJC Scopus subject areas
- Electrical and Electronic Engineering