Monitoring device for detecting faults in an electrical device, particularly in an LC filter circuit in an AC voltage network

US4713604A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Michael Becker · Knittlingen, DE
• Klaus Renz · Fürth, DE

Key dates

• Filing date: Apr 10, 1985
• Grant date: Dec 15, 1987
• Expiry date: Apr 10, 2005

Classification

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

Abstract

A monitoring device connected to an LC filter circuit for determining the occurrence of faults therein includes sensors for measuring the voltage drop across the LC filter circuit and the current flow therethrough. The monitoring device includes simulation circuits for estimating the voltage drop and current flow in response to the actual values of the current flow and voltage drop, respectively. In one position of the double-throw switch, the actual value of the current is compared with an estimated value thereof while in another position of the double-throw switch, an estimated value of the voltage drop is compared with the actual value thereof. Differences between the compared values are detected by a multiplicity of Y-connected limit and counting stages activatable by voltages of different magnitudes and directions for indicating different kinds of faults and for selectively disconnecting the LC filter circuit from a power supply network.