GOST 12119.7-98

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  ГОСТ 12119.7-98

GOST 12119.7−98 electrotechnical Steel. Methods for determining magnetic and electrical properties. A method of measuring the electrical resistivity of the bridge DC

GOST 12119.7−98

Group B39

INTERSTATE STANDARD

Electrotechnical steel

METHODS FOR DETERMINING MAGNETIC AND ELECTRICAL PROPERTIES

A method of measuring the electrical resistivity of the bridge DC

Electrical stell. Methods of test for magnetic and electrical properties.
Method for measurement of specific electric resistance by d. c. bridge

ISS 77.040.20
AXTU 0909

Date of introduction 1999−07−01

Preface

1 DEVELOPED by the Russian Federation, the Interstate technical Committee for standardization MTK 120 «steel Products from ferrous metals and alloys"

INTRODUCED by Gosstandart of Russia

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (minutes N 13 dated 28 may 1998)

The adoption voted:

3 Resolution of the State Committee of the Russian Federation for standardization and Metrology dated December 8, 1998 N 437 inter-state standard GOST 12119.7−98 introduced directly as state standard of the Russian Federation from July 1, 1999

4 REPLACE GOST 12119−80 in section 6

5 REISSUE

1 Scope

This standard specifies a method of measuring the electrical resistivity of 0.10 to 0.60 micro-Ohm·m for chetyrehstennoy the connection circuit.

2 Normative references

The present standard features references to the following standards:

GOST 8.028−86 State system for ensuring the uniformity of measurements. State primary standard and state verification scheme for means of measuring electrical resistance

GOST 12119.0−98 electrotechnical Steel. Methods for determining magnetic and electrical properties. General requirements

3 General requirements

General requirements for methods of measurement according to GOST 12119.0.

Terms used in this standard — GOST 12119.0.

4 Preparation of samples for testing

The samples are made of strips with a length of from 280 to 500 mm, width 20 to 30 mm, thickness from 0.05 to 1.0 mm. Number of samples — at least three.

5 Used equipment

5.1 Clamping device for the test samples shown in figure 1.

Figure 1 — Clamping device

1 — screw clamping; 2 — spring; 3 — insulating film; 4 — plate; 5 — sample;
6 — current source; 7 — base; 8 — prism potential contact; 9 — terminal

Figure 1 — Clamping device

The clamping device must have:

between the inner edge of the current contact and its corresponding potential contact distance of at least 30 mm;

between the potential contacts distance not less than 100 mm.

Potential contacts should be placed on the middle line of the specimen. The width of the contact must be not more than 0.005 length . The resistance of the connecting leads between the current carrying contact bridge and the clamping device must be less than 0.003 Ohms.

5.2 DC Bridge for measuring the electrical resistivity should have a minimum measurement limit of not more than 0.01 Ohm, accuracy class not less than 0.2 according to GOST 8.028.

6 Preparation for measurements

6.1 cross-sectional Area of the sample , m, is calculated by the formula

, (1)

where is the mass of sample, kg;

 — density of material, kg/m;

 — band length of the sample M.

The error of measurement of the sample mass should not go beyond ±0.2%, the length of the strip is ±0,2%.

6.2 Strip clean from the dust; in places of contact of the strip with the pins removed insulation coating, thus reducing the thickness of the strips should not exceed 10 microns.

7 procedures for measuring

7.1 Clamping device with the test sample is connected to the bridge include a current. The density of the current flowing in the strip must not be more than 0.8 A/mm. the displacement of the pointer of the indicator bridge is one notch should match the resistance change of the variable arm of the bridge within the ±0.3%.

7.2 Bridge balance and measure the resistance in Ohms.

8 Rules for processing results of measurements

8.1 electrical resistivity , Ω/m, is calculated by the formula

, (2)

where  — the length of the portion of the band between the potential contacts, m;

 — resistance, Ohms.

8.2 measurement Uncertainty of electrical resistivity should not go beyond ±1%.



The text of the document is verified by:
the official publication of the
Electrotechnical steel.
Specifications. Methods of analysis:
SB. Standards. -
M.: IPK Publishing house of standards, 2003