Small current measurement method for resistivity of large size graphite electrode

A graphite electrode and measurement method technology, applied in the measurement of resistance/reactance/impedance, measurement device, measurement of electrical variables, etc., can solve the problems of backward technology, complex and huge equipment, high use and maintenance costs, and achieve simple and effective measurement equipment. Good and low cost effect

Inactive Publication Date: 2017-02-22
JILIN CARBON
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Problems solved by technology

This measurement method is backward in technology, requires a special rectification device, the equipment is complex and huge, and the cost of use and maintenance is high

Method used

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  • Small current measurement method for resistivity of large size graphite electrode
  • Small current measurement method for resistivity of large size graphite electrode
  • Small current measurement method for resistivity of large size graphite electrode

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0025] Example 1: see image 3 , The relationship between the resistivity of the graphite electrode and the current density, the voltage drop is measured by applying a small to large current through graphite electrodes of different specifications from Φ250mm to Ф500mm. The conclusions obtained are:

[0026] 1. The measurement resolution becomes lower due to the current density, the difficulty of measurement increases, and the requirements for measuring instruments are higher.

[0027] 2. When the current is reduced to a certain level (0.015A / cm 2 ), the stability of the measured value is destroyed, and the measurement error increases significantly; the measurement curve has an inflection point, and after the inflection point, the slope of the curve becomes steeper sharply, and the measured value enters the unstable zone.

[0028] 3. When the current density is greater than or equal to 0.02 amperes, the measurement error is within 0.6%; when the current density is greater tha...

example 2

[0029] Example 2: see Figure 4 , in the small current mode, the relationship between the voltage drop of the graphite electrode and the measurement distance, the experimental conclusion is: when the distance of the voltage measurement section is less than 100mm, the measured value is unstable, and when it is greater than this value, the output voltage is basically linearly proportional to the distance of the measurement section The relationship, or the measured resistivity is basically unchanged.

example 3

[0030] Example 3: see Figure 5 , apply current on both ends of the graphite electrode, and measure the voltage on one side of the graphite electrode circle surface, compare with applying current and measuring voltage on the same straight line parallel to the axis of the graphite electrode circle surface, the conclusion is: apply current on both ends of the graphite electrode The measured value is stable; while the voltage measured by applying current on the same straight line on the surface of the graphite electrode tends to increase on the measured value of the large-scale electrode, which brings a certain measurement deviation.

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Abstract

The invention provides a small current measurement method for the resistivity of a large size graphite electrode. The method is characterized in that the method comprises the steps that 40 to 100 A direct current output by a constant direct current source is applied to both ends of the measured graphite electrode; the reading of the current value is measured and conversed by a shunt; the voltage of the graphite electrode is measured, and the current is measured by two contact probes which impact the cylinder surface of the graphite electrode and are distributed at a certain distance through voltage drop generated by the graphite electrode; two millivolts signals representing the current and voltage are sent to a calculation display meter; calculation is carried out according to a resistivity calculation formula; and the resistivity of the measured graphite electrode is directly displayed. The current density interval is between 0.02A/cm<2> to 0.1A/cm<2>. The distance between two contact probes which are distributed at a certain distance on the cylinder surface of the graphite electrode is from 400mm to 3/4 of the graphite electrode length. The small current measurement method has the advantages of being scientific and reasonable, simple measurement device, convenient measurement, low cost, good effect and so on.

Description

technical field [0001] The invention belongs to the field of instruments and meters, and relates to a small-current measurement method for the resistivity of a large-scale graphite electrode. Background technique [0002] Large-scale graphite electrodes are important materials in the electric furnace steelmaking industry, and the annual domestic demand is nearly 400,000 tons. Large-scale graphite electrode products are generally cylindrical, with diameters ranging from Φ250 to 700mm and lengths ranging from 1500 to 2900mm. Electrode resistivity is an important indicator of graphite electrodes. The traditional measurement method is based on the high current measurement of the carbon industry standard. way, the measured current density is graphite electrode cross section 1A / cm 2 , The working current of the conventional graphite electrode resistivity detection device reaches 1000-4000 amperes, for example, the working current of the graphite electrode measuring resistivity wi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R27/14
CPCG01R27/14
Inventor 乌光钟闻宇马意冰
Owner JILIN CARBON
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