Tap changing assembly for power transformer

• US 6,965,217 B2
• Filed: 02/27/2004
• Issued: 11/15/2005
• Est. Priority Date: 04/03/2003
• Status: Active Grant

• Current Assignee: Maschinenfabrik Reinhausen GmbH (Richard Scheubeck Beteiligungs-Gmbh & Co. KG)
• Original Assignee: Maschinenfabrik Reinhausen GmbH (Richard Scheubeck Beteiligungs-Gmbh & Co. KG)
• Inventors: Dohnal, Dieter, Viereck, Karsten
• Primary Examiner(s): Riley, Shawn
• Application Number:
  US10/790,326
• Publication Number:
  US 20040196010A1
• Time in Patent Office: 627 Days
• Field of Search: 323/257, 323/258, 323/256
• US Class Current: 323/257
• CPC Class Codes: H01H 2009/0061 Monitoring tap change switching devices
• CPC Class Codes: H01H 9/168 making use of an electromagnetic wave communication

Abstract

A tap changing assembly for power transformers having vacuum interrupters each of which is associated with a radio interrogated surface wave sensor capable of detecting whether the respective vacuum interrupter opens circuit in a timely manner. The sensors are interrogated by an interrogating unit transmitting high-frequency signals to the sensors and associated with a monitoring circuit responsive to signals received by the interrogating unit for signalling the status of the vacuum interrupter.

Claims

1. A tap-changing assembly for power transformers, comprising:

a tap changer having at least one vacuum interrupter open-circuiting upon a tap change and conducting an electric current in an absence of a tap change; and

a monitoring device for monitoring timely operation of said vacuum interrupter, said monitoring device comprising;

at least one interrogatable surface wave sensor proximal to a conductor in circuit with said vacuum interrupter,

an interrogating unit spaced from said vacuum interrupter and transmitting a high-frequency signal to and receiving a high-frequency signal from said sensor, and

a monitoring circuit electrically connected to said interrogating unit and responsive to a signal received by said interrogating unit from said sensor for signalling a status of said vacuum interrupter.

2. The tap-changing assembly defined in claim 1 wherein the tap changer is configured for a polyphase system and each phase is provided with at least one of said vacuum interrupters and each of said vacuum interrupters is provided with a respective one of said surface wave sensors.

3. The tap-changing assembly defined in claim 2 wherein said vacuum interrupters and surface wave sensors are located in an oil-containing housing of said tap changer and said interrogating unit and monitoring circuit are located in a region of a motor drive for said tap changer.

4. The tap-changing assembly defined in claim 2 wherein said surface wave sensors are radio-interrogated surface wave sensors and said interrogating unit has an oscillator operating in a frequency range of 100 MHz to 3 GHz and an antenna.

5. The tap-changing assembly defined in claim 2, further comprising contacts connected to said monitoring circuit for establishing critical time points for interrogating said sensors.