Method and circuit arrangement for measuring earth leakages in intrinsically safe current feeds

US6864673B2 · kind B2 · utility

Assignee

• DBT Automation GmbH · DE

Inventors

• Jens Titschert · Grafenau, DE
• Emmanuel Charruau · Grafenau, DE
• Helmut Hermann · Bochum, DE

Key dates

• Filing date: Feb 28, 2003
• Grant date: Mar 8, 2005
• Expiry date: Feb 28, 2023

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R27/18
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method and a circuit arrangement (10) for the measurement of earth leakage in intrinsically safe current feeds to electronic control units (4) for underground mining installations and machines, whereby at least one earthed control unit is connected to the two intrinsically safe potentials of an intrinsically safe direct current supply (1) and at least one earth leakage sensor (20) is provided for earth leakage measurement with which steps of the periodical application of a test potential (Umess) from an intrinsically safe switchable test voltage source (21) to an RC-element (22), isolated from earth (8) by means of decoupling capacitors (C1, C2), measurement of the charging or discharging current behaviour of the RC-element (22) after each switching of the test voltage source (21) and comparison of the measured charging or discharging behaviour with stored reference data.