Comportamento de transformadores de corrente sob condições de energização de um transformador de potência

Abstract

The objective of this dissertation consists in the study of the neutral current on the connection of current transformers when in secondary, shows or not an unbalanced level during the process of energization in a power transformer. These currents according to the test realized in the laboratory can cause disconnection and interruption, causing big damages. To illustrate this work the results are showing by the software ATP. By the end, some alternatives to avoid that the neutral current become sensitive in a wrong way during the process of energization of a power transformer are showing in a conclusive way. The proposal methodology contemplates the following stages: - Considerations about current transformer, which remember some simple rules that allow to define the characteristics of a current transformer TC ; - Analysis and modeling of current transformers for protection service; - Experimental assays, which contemplates the study of the neutral current in TC's, caused by unbalanced loads of the secondary current transformers connected in grounding star; - Computational assays, in this stage the computational assays were carried through using the computational tool ATP.