Switch comprising a testable current transformer, and method for testing a current transformer of a switch

US8817442B2 · kind B2 · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Thomas Driehorn · Berlin, DE
• Gerd Muller · Falkensee, DE

Key dates

• Filing date: Jul 20, 2012
• Grant date: Aug 26, 2014
• Expiry date: Dec 18, 2032

Classification

• Technology area (CPC H): Electricity
• CPC primary: H02H3/08
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

A switch and a method for testing the power transformers of a power supply of the switch are provided, wherein each power transformer generates an analog transformer voltage corresponding to the alternating current, wherein an electronic trip unit, to which each transformer voltage is applied, compares a current derived from each transformer voltage with a current condition, and wherein a rectifier circuit connected to the power transformer charges a capacitor which feeds the power supply of the trip unit. A switching device short-circuits each rectifier circuit when a predefined capacitor voltage is reached. To provide the protective function of the switch, a monostable multivibrator is connected to one pole of each power transformer, wherein each monostable multivibrator is set by the respective transformer voltage and reset after a predefined time, and wherein the level at the output of each monostable multivibrator is used to test the respective power transformer.