Electrode configuration for LiMCA

• US 8,928,306 B2
• Filed: 10/29/2008
• Issued: 01/06/2015
• Est. Priority Date: 03/04/2004
• Status: Active Grant

• Current Assignee: Novelis Incorporated (Hindalco Industries Limited)
• Original Assignee: Novelis Incorporated (Hindalco Industries Limited)
• Inventors: Marcotte, Jacques, Slusarenko, Yuhil
• Primary Examiner(s): Valone, Thomas F
• Application Number:
  US12/290,257
• Publication Number:
  US 20090058396A1
• Time in Patent Office: 2,260 Days
• Field of Search: None
• US Class Current: 324/71.4
• CPC Class Codes: G01N 15/02 Investigating particle size or size distribution by measuring osmotic pressure G01N7/10; investigating sedimentation of particle suspensions G01N15/04; investigating individual particles G01N15/10
• CPC Class Codes: G01N 15/12 by observing changes in resistance or impedance across apertures when traversed by individual particles, e.g. by using the Coulter principle
• CPC Class Codes: G01N 27/403 Cells and electrode assemblies
• CPC Class Codes: G01N 33/205 in liquid state, e.g. molten metals

Abstract

The present invention provides a method and apparatus for reducing electromagnetic noise pick up in a Liquid Metal Cleanliness Analyzer (LiMCA), used to detect and measure particles in molten metal. An first electrode inserted in the molten metal is electrically insulated from second and third electrodes, also inserted in the molten metal. Molten metal and particles pass between the first electrode and the second and third electrodes through a passage in the electrical insulation. The second and third electrodes have a configuration with respect to the first electrode sufficient to establish symmetrical current loops between the first electrode and the second and third electrodes when a current is supplied to the second and third electrodes. The current is supplied from an ultra-capacitor. Electromagnetic noise in the symmetrical current loops is detected and is added in opposition to reduce the amplitude of the electromagnetic noise.

Claims

1. A method of making measurements in a Liquid Metal Cleanliness Analyzer (LiMCA), having a body of molten metal containing particles, electrically insulating wall means having a passage formed therein for passage of the molten metal, a first electrode positioned on one side of the wall means and at least one additional electrode inserted in the molten metal on an opposite side of the wall means to the first electrode and voltage recording means connected between the first electrode and the at least one additional electrode, said method comprising:

a) drawing molten metal in one direction through said passage to immerse said first electrode in molten metal;

b) supplying current at an initial predetermined level to the first electrode and to the at least one additional electrode to create a current loop between the at least one additional electrode and the first electrode, said current loop generating a wanted pulse signal that is recorded by the voltage recording means, and wherein said current is supplied from an ultra-capacitor via at least one voltage control resistor associated with the at least one additional electrode;

c) monitoring the change in the current from said ultra-capacitor;

d) adjusting said at least one voltage control resistor associated with the at least one additional electrode to re-adjust the current output to said predetermined level during the course of one measurement while said voltage recording means is temporarily prevented from recording the wanted pulse signal, thereby maintaining said supply of current at said predetermined level for a period of time required for said one measurement; and

e) expelling molten metal in an opposite direction through said passage while recharging said ultra-capacitor.