CS273568B1 - Arrangement of rogowski-chattock potentiometer - Google Patents

Abstract

The arrangement of the Rogowski-Chattock potentiometer for measurement of the magnetic voltage on the surface of the magnetic body is analyzed. The winding of the potentiometer is divided into one central part and two marginal parts, which are of the same length, cross section and winding density. All these three parts are connected in series with the analogous sense of the winding. The ratio of the product of the cross section of the core of the central part and density of the winding of the central part to the product of the core of the marginal part and density of the winding of the marginal part is in the ratio of the length of the marginal part to the sum of this length and distance of the ends of the marginal parts from the surface of the measured sample.<IMAGE>

Description

The present invention relates to the provision of a Rogowski-Cattatt potentiometer for measuring the magnetic stress on the surface of a magnetized body.

The measurement is normally carried out by a Rogowski-Chattock potentiometer, which is a coil wound on a core of constant cross-section of conductive and non-magnetic material with constant thread density along its entire length. The magnetic stresses along its axis are proportional to its coil magnetic flux, and the integration of the voltage induced by time changes of this flux is determined. When measuring the magnetic stress, its ends are placed perpendicular to the surface of the magnetized body.

In many cases the ends cannot be applied directly to the body surface. The necessary magnetizing devices are generally used by windings placed on the chassis, into whose cavities the measured samples are inserted. The ends of the potentiometer are then separated from the sample surface at least by the thickness of the cutter. In addition, it is necessary to protect the ends of the potentiometer from mechanical damage during sample insertion, which is especially necessary for continuous meters, where irregularities in the surface of the running belts are to be taken into account. Measurement errors occur due to the distance between the ends of the potentiometer and the sample surface.

This drawback removes the arrangement of the Rogowski-Chattock potentiometer according to the invention. The essence is that His winding is arranged in one central part and two edge parts. The peripheral parts have the same cross-section, the same winding density and the standing length. The ratio of the cross-section product of the center part and the winding density of the center part to the product of the cross section of the core of the edge part and the winding density of the edge part is equal to the ratio of the length of the edge. All three winding parts are connected in series with a common sense.

The advantage of the arrangement is to increase the accuracy of the magnetic measurements due to the suppression of the dependence of the magnetic voltage measurement on the distance of the ends of the Rogowski-Chattock potentiometer from the surface of the samples. In this case, the integral of the sum of the electrical voltages induced in all three parts of the Rogowski-Chattock potentiometer approximates the magnetic voltage on the sample surface.

An example of an arrangement of a Rogowski-Chattock potentiometer according to the invention is shown schematically in Fig. 1 and Fig. 2 shows the wiring of the Rogowski-Chattock potentiometer in a particular measuring application.

The Rogoweki-Chattock potentiometer ee consists of the center portion 1 and two edge portions 2. The edge portions 2 have the same cross-section, the same winding density and the same length b. The middle portion 11 has a proportionality constant A between the coil flow and the magnetic voltage, and the edge portion 2 has a proportionality constant 8. The proportionality constant A of the middle portion 1 is proportional to the product of the winding density of the middle portion JL and the cross section of the core. The proportionality constant B of the edge portion 2 is proportional to the product of the winding density of the edge portion 2 and the core cross section of the edge portion 2. The edge portion 2 and the middle winding portion 11 are connected in series with a consistent sense of winding. In the actual measurement of the magnetic stress on the surface 3 of the magnetized sample, the edge portions 2 are spaced from the surface 3 of the sample by a distance δ. 2a assuming linear loss of magnetic voltage from the sample surface 3, ie when ^U BM " ^U mCD" ^to V 'where U _m £ Q is the magnetic voltage at the surface 3, the sample between places C and Dy ^u m (y) is the magnetic voltage CD of the same length at a distance y from the surface of the sample 3, the auxiliary is a constant, y is the distance from the surface of the sample 3, which is considered to U _m (y) is a coil flux _ _c j JL central part is given by

-cl “ ^Al V ^{a + b} >“ ^{A / U} mCO “ ^k (a ^{+ b} ) /.

wherein A is a proportionality constant central portion 1, and, js distance from two edge portions of the surface 3 of the sample, b is the length of the edge portion 2 and the coil flux _ _c2 marginal sections 2 Relationship $

CS 273 568 Bl

2.

_c2 »B / U _m (a) - U _m (a + b) / = B kb, where B is the proportionality constant of the edge portions 2.

It follows from these equations that the magnetic voltage U _mCD on the surface 3 of the sample can be expressed in shape

^U mCD ' ₊ - £ 2 AB a + b b • Induced meter voltages are Up resp. Ug ve etředni , respectively. peripheral Parts J., respectively. 2 potenti ^U 1 d _cl / dt and Ug - d c2 ^{/ dt} , so ^U mCO , i AND / U] + (a + b) b Ug / dt If ee density or winding cross section in peripheral parts 2 achieves this . AND - (B) b ^L '9 a + b Yippee ^U mCO 1 and - · AND (u ^ Ug) dt,

that is, the magnetic voltage U _mCD on the sample surface 3 can be determined from a simple sum of the two induced voltages Uj and Ug.

The Rogowski-Chattock potentiometer according to the invention can be used in all magnetic measurements requiring determination of the magnetic stress on the sample surface.

Claims (2)

SUBJECT OF THE INVENTION Rogowski-Chattock potentiometer arrangement, characterized in that its winding is formed by one central part (1) and two edge parts (2) having the same length (b), the same cross-section and the same winding density, where the portion (1) and the winding density of the central portion (1) to the product of the core cross section of the edge portion (2) and the winding density of the edge portion (2) Is equal to the ratio of the length (b) of the edge portion (2) to the sum of the distance (a) of the ends of the edge portion (2) from the surface (3) of the sample to be measured are wired in series with a consistent sense of winding.