Ricerc@Sapienza

The paper reports laboratory tests to evaluate the thermal behavior of thermal-magnetic protection circuit-breakers. They are characterized by a rather variable intervention mode according to the environmental and operating thermal conditions. The scope is verify a relationship between the thermal image of the circuit-breaker and the phenomena that lead the actuator mechanism to tripping. The work shows a various types of temperature sensors and location, highlighting their performance, according to these measurement tests.

The paper focuses on the time domain output-only technique called Data-Driven Stochastic Subspace Identification (DD-SSI); in order to identify modal models (frequencies, damping ratios and mode shapes), the role of its user-defined parameters is studied, and rules to determine their minimum values are proposed. Such investigation is carried out using, first, the time histories of structural responses to stationary excitations, with a large number of samples, satisfying the hypothesis on the input imposed by DD-SSI.