Monitoring system for an LC filter circuit in an AC power network

US4409542A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Michael Becker · Knittlingen, DE
• Alfons Fendt · Erlangen, DE
• Dusan Povh · Nuremberg, DE
• Klaus Renz · Fürth, DE
• Gerhard Schuch · Erlangen, DE
• Hermann Waldmann · Radebeul, DE

Key dates

• Filing date: May 26, 1981
• Grant date: Oct 11, 1983
• Expiry date: May 26, 2001

Classification

• Technology area (CPC H): Electricity
• CPC primary: H02H7/16
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

A monitoring system for measuring the phase currents of a filter circuit, the monitoring system having current measuring transformers coupled to respective filter sections for suppressing the harmonic content. Voltage measuring transformers are provided for measuring the network phase voltages, each such voltage measuring transformer being coupled to an electronic filter simulator and a filtering section for suppressing harmonic content. The fundamental frequency component of the measured phase currents and the simulated phase currents are conducted to transient comparator circuitry which is coupled to indicating and triggering circuitry having individual counter stages. Only rapid variations between the measured and simulated phase currents will result in fault indications, thereby preventing false indications resulting from variations in temperature.