engleski

LF signal injection for earth-fault localization in unearthed distribution network

Unearthed neutral is often used in industrial networks, which require continuous power supply, and in distribution networks where the network capacitive current is not too high ; or it is uneconomical to move to compensated grounding. Unearthed networks can remain in operation during an earth-fault, but fast determination of the faulty line is the key for prevention of further fault escalation. Signal injection is one of the fault location methods often used in LV unearthed networks. The possibility of application of this method in MV networks is dependent on how to inject the signal into unearthed phases with voltages ranging from 10 to 35 kV. This paper presents the signal injection circuit, which consist of three inductive voltage transformers (IVTs). The specifics of IVT design for signal injection are discussed. The application of the LF signal injection during an earth-fault was simulated on the model of an unearthed distribution network in EMTP. An intermittent fault and ring-type network connection were considered as possible cases.

Unearthed network ; Earth-fault ; Low-frequency signal injection ; Inductive voltage transformer

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