Three- or four-pole low-voltage power switch with Rogowski coils operating as current sensors

• US 7,309,993 B2
• Filed: 03/02/2005
• Issued: 12/18/2007
• Est. Priority Date: 03/04/2004
• Status: Active Grant

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Driehorn, Thomas, Krauss, Andreas, Pancke, Andreas, Redmann, Ilka, Röhl, Wolfgang
• Primary Examiner(s): Benson, Walter
• Application Number:
  US10/591,461
• Publication Number:
  US 20070182401A1
• Time in Patent Office: 1,021 Days
• Field of Search: 324/509, 324/515, 361/31, 361/42, 361/62
• US Class Current: 324/509
• CPC Class Codes: H02H 1/0007 concerning the detecting means in general G01R or other subclasses of G01; reed switches H01H71/2445
• CPC Class Codes: H02H 3/32 involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors

Abstract

A three or four pole low-voltage power switch is disclosed wherein the switch is partly provided with a device for detecting ground faults. For this purpose, the current vectorial sum must be produced in the three or four conductors of a monitored network. For the switches of this type, output signals received from Rogowski coils are directed via resistances to an integration capacitor whose voltage forms an input signal of another measuring amplifier representing the current sum of a monitored network. The output signal of the measuring amplifier is, afterwards processed in a known manner in the microprocessor of an excess-current trip.

Claims

1. At least one of a three-pole and four-pole low-voltage power switch, comprising:

an electronic overcurrent release;

a device for ground-fault detection; and

Rogowski coils usable as current sensors for a power network, outputs of the Rogowski coils each being taken via an RC low-pass filter to an instrumentation amplifier of the electronic overcurrent release, and

output signals of all the Rogowski coils being taken via resistors in common to an integration capacitor, whose voltage forms an input signal of an additional instrumentation amplifier indicating summation current in the power network.

2. The switch of claim 1, wherein an output signal of the additional instrumentation amplifier is processed further in a microprocessor of the electronic overcurrent release.