CORONA TESTING APPARATUS INCLUDING ENERGY STORAGE MEANS FOR INDICATING TIME DIFFERENCE BETWEEN CORONA SIGNALS

• US 3,612,992 A
• Filed: 09/30/1969
• Issued: 10/12/1971
• Est. Priority Date: 09/30/1969
• Status: Expired due to Term

• Current Assignee: John C. Cronin
• Original Assignee: John C. Cronin
• Inventors: Cronin, John C.
• Primary Examiner(s): Lynch, Michael J.
• Application Number:
  US04/862,431
• Time in Patent Office: 742 Days
• Field of Search: 324/52,72,68,55 340/16 73/71.4
• US Class Current: 324/519
• CPC Class Codes: G01R 31/08 Locating faults in cables, transmission lines, or networks
• CPC Class Codes: H02B 13/065 Means for detecting or reacting to mechanical or electrical defects

Abstract

Apparatus for the detection and location of corona within the casing of fluid-filled electrical apparatus. First and second mechanical to electrical transducers are disposed to pickup corona initiated mechanical vibrations in the apparatus under test. When a corona discharge occurs, the electrical signal from the first transducer to receive the mechanical vibrations is used to initiate the charging of a capacitor. Then, the signal provided by the other transducer, in response to the same corona discharge, is used to terminate the charging of the capacitor. The magnitude of the charge or voltage across the capacitor is a direct indication of the difference between the distances separating each transducer from the source of the corona.

Claims

1. Apparatus for corona testing electrical inductive apparatus having a casing containing electrical windings disposed in a fluid, comprising:

first and second mechanical to electrical transducers adapted to be disposed at predetermined spaced locations which are in vibration responsive association with the electrical apparatus, energy storage means, first and second unidirectional sources of electrical potential, with said first and second sources being positive and negative sources, respectively, first, second, third and fourth switching means switchable between conductive and nonconductive states, said first and second switching means being connected to charge said energy storage means from said first and second sources of electrical potential, respectively, when said first and second switching means are in their conductive states, logic means having first and second input terminals connected to said first and second transducers, respectively, and first and second output terminals associated with the first and second input terminals, respectively, said first and second output terminals being connected to effect the switching of said first and second switching means, respectively, when they provide an output signal, said logic means directing the first signal to be applied to one of its input terminals from the transducers, To the output terminal associated with said one input terminal, and blocking a later arriving signal from the other transducer from the other output terminal, said third and fourth switching means being connected such that one will terminate the charging of said energy storage means in response to the later arriving signal, and means measuring the magnitude of the voltage across said energy storage means, which magnitude is responsive to the difference between the distances separating said first and second transducers from the source of the vibration which initiated the signals, and with the polarity of the voltage indicating which of the transducers is closer to the source of vibrations.

2. The apparatus of claim 1 wherein the third and fourth switching means are connected to switch to their conductive states when a signal is applied to the the first and second input terminals, respectively, of the logic means, with the third switching means being connected across the second switching means and the energy storage means, and the fourth switching means connected across the first switching means and the energy storage means, the switching of the third switching means to its conductive state terminating the charging of the energy storage means when it is charging in response to the second switching means, and the switching of the fourth switching means to its conductive state terminating the charging of the energy storage means when it is charging in response to the first switching means.