Energy losses in magnetic materials. Magnetic losses Determination of specific losses for remagnetization of iron

GOST 12119.4-98

INTERSTATE STANDARD

Electrical steel

magnetic field

Official edition

INTERSTATE COUNCIL FOR STANDARDIZATION, METROLOGY AND CERTIFICATION

Foreword

1 DEVELOPED by the Russian Federation, Interstate Technical Committee for Standardization MTK 120 "Metal products from ferrous metals and alloys"

INTRODUCED by Gosstandart of Russia

2 ADOPTED by the Interstate Council for Standardization, Metrology and Certification (Minutes No. 13-98 dated May 28, 1998)

3 Decree State Committee Russian Federation on standardization and metrology dated December 8, 1998 No. 437, the interstate standard GOST 12119.4-98 was put into effect directly as state standard Russian Federation since July 1, 1999

4 INSTEAD OF GOST 12119-80 in part of section 4

© IPK Standards Publishing House, 1999

This standard cannot be fully or partially reproduced, replicated and distributed as an official publication on the territory of the Russian Federation without the permission of the State Standard of Russia

INTERSTATE STANDARD

Electrical steel

METHODS FOR DETERMINING MAGNETIC AND ELECTRIC PROPERTIES

Method for measuring specific magnetic losses and the effective value of the intensity

magnetic field

electrical steel.

Methods of test for magnetic and electrical properties.

Method for measurement of specific magnetic losses and actual value of magnetic field intensity

Introduction date 1999-07-01

1 area of ​​use

This International Standard specifies a method for determining specific magnetic losses from 0.3 to

50.0 W / kg and the effective value of the magnetic field strength from 100 to 2500 A / m at frequencies of magnetization reversal of 50-400 Hz using the wattmeter and ammeter method.

It is allowed to determine the values ​​of magnetic quantities at remagnetization frequencies up to 10 kHz on ring samples and on samples from strips.

2 Normative references

GOST 8.377-80 GSI. The materials are soft magnetic. Methods for performing measurements when determining static magnetic characteristics

GOST 8476-93 Analog electrical indicating instruments direct action and accessories for them. Part 3 Special Requirements for wattmeters and varmeters

GOST 8711-93 Direct-acting analog indicating electrical measuring instruments and auxiliary parts to them. Part 2: Particular requirements for ammeters and voltmeters

GOST 12119.0-98 Electrical steel. Methods for determining magnetic and electrical properties. General requirements

GOST 13109-87 Electrical energy. quality requirements electrical energy in electrical networks of general purpose

GOST 21427.1-83 Electrical cold-rolled anisotropic sheet steel. Specifications

GOST 21427.2-83 Electrical cold-rolled isotropic thin sheet steel. Specifications

3 General requirements

General requirements for test methods - according to GOST 12119.0.

The terms used in this standard are in accordance with GOST 12119.0.

Official edition

4 Preparation of test specimens

4.1 Test specimens shall be insulated.

4.2 Ring-shaped samples are assembled from stamped rings with a thickness of 0.1 to 1.0 mm or wound from a tape with a thickness of not more than 0.35 mm and placed in cassettes of insulating material with a thickness of not more than 3 mm or non-ferromagnetic metal with a thickness of not more than 0.3 mm. The metal cassette must have a gap.

The ratio of the outer diameter of the sample to the inner should be no more than 1.3; the cross-sectional area of ​​the sample is not less than 0.1 cm 2 .

4.3. Samples for the Epstein apparatus are made from strips with a thickness of 0.1 to 1.0 mm, a length of 280 to 500 mm, and a width of (30.0 ± 0.2) mm. The strips of the sample should not differ from each other in length by more than ± 0.2%. The cross-sectional area of ​​the sample should be between 0.5 and 1.5 cm 2 . The number of bands in the sample must be a multiple of four, the minimum number of bands being twelve.

Samples of anisotropic steel are cut along the rolling direction. The angle between the directions of rolling and cutting of strips should not exceed G.

For samples of isotropic steel, half of the strips are cut along the rolling direction, the other - across. The angle between the rolling and cutting directions must not exceed 5°. The strips are grouped into four packages: two - from strips cut along the rolling direction, two - across. Packages with equally cut strips are placed in parallel coils of the apparatus.

It is allowed to cut strips at the same angle to the direction of rolling. The direction of rolling for all strips laid in one coil must be the same.

4.4 Sheet samples are made from 400 to 750 mm long. The length of the sheet must be at least the outer length of the yoke: the width of the sheet must be at least 60% of the width of the solenoid window. The tolerance in length should not exceed ± 0.5%, in width - ± 2 mm.

The surface and shape of the sheets must comply with GOST 21427.1 and GOST 21427.2.

5 Applied equipment

5.1 Installation. The installation diagram is shown in Figure 1.

5.1.1 Voltmeters PV1 - for measuring the average rectified voltage value and subsequent determination of the amplitude of magnetic induction and PV2 - for measuring the effective value of voltage and subsequent determination of the shape factor of its curve must have a measurement limit from 30 mV to 100 V, the maximum input current is not more than 5 mA , accuracy class not lower than 0.5 according to GOST 8711.

It is allowed to use a voltage divider to the PV1 voltmeter to obtain readings numerically equal to the amplitudes of the magnetic induction.

5.1.2 The PW wattmeter for measuring active power and subsequent determination of specific magnetic losses must have a measurement limit of 0.75 to 30 W, a rated power factor of not more than 0.1 at a frequency of 50 Hz and 0.2 at a higher frequency; accuracy class not less than 0.5 at a remagnetization frequency from 50 to 400 Hz or not less than 2.5 - at a frequency of more than 400 Hz according to GOST 8476.

It is allowed to use a voltage divider to the wattmeter to obtain readings numerically equal to the values ​​of specific magnetic losses. The output of the voltage divider must be connected to the parallel circuit of the wattmeter, the input - to the winding II of the T2 sample.

5.1.3 The RA ammeter for measuring the effective value of the magnetizing current and the subsequent determination of the effective value of the magnetic field strength must have a measurement limit of 0.1 to 5.0 A, an accuracy class of at least 0.5 according to GOST 8711. It is allowed to increase the smallest measurement limit up to 1.0 A when monitoring the load of the current circuit of the wattmeter. The maximum power consumed by the ammeter when measuring with samples from sheets with a width of more than 250 mm should be no more than 1.0 V A; for other samples - no more than 0.2 V - A

5.1.4 Frequency counter PF for measuring frequency with an error not exceeding ±0.2%.

5.1.5 Power source C for sample magnetization should have a low-frequency generator with a power amplifier or a voltage regulator with a 50 Hz frequency stabilizer. The voltage non-sinusoidality factor of the loaded power source should not exceed 5% according to GOST 13109. The rated power of the source at a magnetization reversal frequency of 50 Hz should be at least 0.45 kVA per 1.0 kg of sample mass and at least 0.3 kV-A for values indicated in table 1.

Table 1

It is allowed to use the amplifier with feedback to get the shape of the curve magnetic flux sample close to sinusoidal. The coefficient of non-sinusoidality of the shape of the EMF curve in the winding should not exceed 3%; the power consumed by the voltage feedback circuit must not exceed 5% of the measured magnetic losses.

5.1.6 Voltmeters PV1 and PV2, the voltage circuit of the wattmeter PW and the feedback of the amplifier must consume no more than 25% of the measured value.

5.1.7 Coil 77 for compensating the magnetic flux outside the sample must have the number of turns of the winding I not more than fifty, the resistance - not more than 0.05 Ohm, the resistance of the winding II - not more than 3 Ohm. The windings are laid on a cylindrical frame made of non-magnetic insulating material with a length of 25 to 35 mm and a diameter of 40 to 60 mm. The axis of the coil must be perpendicular to the plane of the lines of force of the sample when it is fixed on the Epstein apparatus. The relative difference between the coefficients of mutual inductance of the T1 coil and the Epstein apparatus without a sample should not exceed ±5%.

It is allowed to exclude coil T1 from the circuit (see Figure 1) with a magnetic flux outside the sample that does not exceed 0.2% of the measured one.

5.1.8 Magnetizing I and measuring II windings of the ring sample T2 must comply with the requirements of GOST 8.377.

5.1.9 The Epstein apparatus used for testing samples composed of strips, T2, shall have four coils on frames of non-magnetic insulating material with the following dimensions:

inner window width - (32.0±0.5) mm;

height - from 10 to 15 mm;

frame wall thickness - from 1.5 to 2.0 mm;

the length of the section of the coil with the winding is not less than 190 mm;

coil length - (220±1) mm.

The number of turns in the windings of the apparatus is selected in accordance with Table 2.

table 2

5.1.10 The sheet apparatus used for testing specimens T2 shall have a solenoid and two yokes. The design of the yokes must ensure the parallelism of the contacting surfaces and mechanical rigidity, which excludes the influence on the magnetic properties of the sample. The width of the poles of electrical steel yokes must be at least 25 mm, those of precision alloys - 20 mm. Magnetic losses in the yokes should not exceed 5% of the measured ones; the relative difference of the amplitudes of the magnetic flux in the yokes should not go beyond ±15%.

It is allowed to use devices with open yokes to measure the relative change in specific magnetic losses, for example, when assessing the residual voltage according to GOST 21427.1.

The solenoid must have a frame made of non-magnetic insulating material, on which the measuring winding II is first placed, then the magnetizing winding I is placed with one or more wires. Each wire is evenly laid in one layer.

The relative maximum difference in the amplitudes of the magnetic induction in the area of ​​the sample inside the solenoid should not go beyond ±5%.

6 Preparing for measurements

6.1 Samples from strips, sheets or annular shapes are connected as shown in figure 1.

6.2 Samples from strips or sheets are placed in the apparatus. Samples from the strips are placed in the Epstein apparatus, as indicated in Figure 2.

It is allowed to fix the position of strips and sheets in the apparatus, creating a pressure of not more than 1 kPa perpendicular to the surface of the sample outside the magnetizing coils.

6.3 Calculate the cross-sectional area S, m 2, of the samples:

6.3.1 The cross-sectional area 5, m 2, for annular-shaped samples of a material with a thickness of at least 0.2 mm, is calculated by the formula

Figure 2 - Scheme of laying strips of the sample

O)

where m is the mass of the sample, kg;

D, d - outer and inner diameters of the ring, m; y is the density of the material, kg / m 3.

The density of the material y, kg / m 3, is selected according to Appendix 1 of GOST 21427.2 or calculated by the formula

y \u003d 7865 - 65 (tf Si + 1.7A ^\u003e,

where K S i and Ad) - mass fractions of silicon and aluminum,%.

6.3.2 The cross-sectional area S, m 2 , for annular specimens of material less than 0.2 mm thick, is calculated by the formula

to y (D + d) (1 + C t

(3)

where C y \u003d y is the ratio of the density of the insulating coating to the density of the sample material, where y p is the insulation density, taken equal to 1.6 10 3 kg / m 3 for an inorganic coating and

1.1 ■ 10 3 kg / m 3 - for organic;

K, - fill factor, determined as specified in GOST 21427.1.

6.3.3 The cross-sectional area S, m 2 , of samples composed of strips for the Epstein apparatus, is calculated by the formula

(4)

where ^ - strip length, m.

6.3.4 The cross-sectional area of ​​the sheet sample S, m 2, is calculated by the formula

(5)

where 1 L is the length of the sheet, m.

6.4 The error in determining the mass of the samples should not exceed ±0.2%, the outer and inner diameters of the ring - ±0.5%, the length of the strips - ±0.2%.

6.5 Measurements at a magnetic induction amplitude value of less than 1.0 T are carried out after demagnetization of the samples in a field with a frequency of 50 Hz.

Set the voltage corresponding to the amplitude of the magnetic induction of at least 1.6 T for anisotropic steel and 1.3 T for isotropic steel, then gradually reduce it.

The demagnetization time must be at least 40 s.

When measuring magnetic induction in a field with a strength of less than 1.0 A/m, the samples are kept after demagnetization for 24 hours; when measuring induction in a field with a strength of more than

1.0 A/m exposure time can be reduced to 10 min.

It is allowed to reduce the exposure time with a relative difference in the induction values ​​obtained after normal and reduced exposures, within ± 2%.

6.6 The upper limits of the values ​​of the measured magnetic quantities for the samples of an annular shape and composed of strips must correspond to the amplitude of the magnetic field strength of not more than 5 10 3 A/m at a magnetization reversal frequency of 50 to 60 Hz and not more than 1 10 3 A/m - at higher frequencies; lower limits - the smallest values ​​​​of the amplitudes of magnetic induction, given in table 3.

Table 3

The smallest value of the magnetic induction amplitude for sheet samples should be equal to 1.0 T.

6.7 For a PV1 voltmeter calibrated in average rectified values, the voltage

V B, corresponding to the given amplitude of the magnetic induction B ^, Tl, and the magnetization reversal frequency /, Hz, is calculated by the formula

U cp = 4fSW 2 B mx (\-%, (6)

where S is the cross-sectional area of ​​the sample, m 2 ;

W 2 - the number of turns of the winding of the II sample;

g 2 - the total resistance of the winding II sample T2 and coil 77, Ohm; g e - equivalent resistance of devices and devices connected to the winding II of sample T2, Ohm, calculated by the formula

(7)

where g p g p, gzg, g A are the active resistances of the voltmeters PV1, PV2, the voltage circuit of the wattmeter PW and the voltage feedback circuit of the power amplifier, respectively, Ohm.

The value - in formula (6) is neglected if its value does not exceed 0.002.

6.8 For the voltmeter PV1, calibrated in the effective voltage values ​​​​by the sine of the far form, the value of the value U, V, is calculated by the formula

U=4.44fSJV 2 B max (l-^).

6.9 In the absence of coil T1, calculate the correction AU, V, due to the magnetic flux outside the sample, according to the formula

A U = 4/U", ^ Mo (^ -S)f-U> (9)

where is the number of turns of the windings of the sample T2,

But - 4th 10 -7 - magnetic constant, H/m;

S 0 - cross-sectional area of ​​the measuring winding of the sample, m 2 ;

S is the cross-sectional area of ​​the sample, determined as specified in 6.3, in m 2 ;

1 C p - the average length of the magnetic field line, m.

For ring-shaped samples, the average length of the magnetic field line / sr, m, is calculated by the formula

l cp = y(D + d). 0°)

In standard tests for a sample of strips, the average length l^, m, is taken equal to 0.94 m. If it is necessary to improve the accuracy of determining magnetic quantities, it is allowed to choose the values ​​/ cp from table 4.

Table 4

For a sheet sample, the average length of the magnetic field line / cf, m, is determined by the results of the metrological certification of the installation;

/ max - current amplitude, A; calculated depending on the amplitude of the voltage drop U R p ^, V, on a resistor with a resistance R, Ohm, included in the magnetizing circuit, according to the formula

(P)

or according to the average rectified value of the EMF t / cpM, V, induced in the winding II of the coil 77 with the winding I included in the magnetizing circuit, according to the formula

I and cf.s (12)

where M is the mutual inductance of the coil, H; not more than 1 10 -2 H;

/ - remagnetization frequency, Hz.

6.10 When determining the specific magnetic losses in the Epstein apparatus, one should take into account the inhomogeneity of the magnetization of the corner parts of the magnetic circuit by introducing the effective mass of the sample m and kg, which for samples from strips is calculated by the formula

4

(13)

where m is the mass of the sample, kg;

^ - strip length, m.

For annular samples, the effective mass is assumed to be equal to the mass of the sample.

The effective mass of the sheet sample is determined by the results of the metrological certification of the installation.

7 Measurement procedure

7.1 Determination of specific magnetic losses is based on the measurement of the active power consumed by the magnetization reversal of the sample and consumed by the devices PV1, PV2, PW and the amplifier feedback circuit. When testing a sheet sample, losses in yokes are taken into account. Active power is determined indirectly by the voltage on the winding II of sample T2.

7.1.1 At the installation (see Figure 1), the keys S2, S3, S4 are closed and the key S1 is opened.

7.1.2 Set the voltage £ / sr, U or (U ^ + DU), V, according to the PV1 voltmeter; remagnetization frequency /, Hz; check on the ammeter PA that the wattmeter PW is not overloaded; close the key S1 and open the key S2.

7.1.3 If necessary, regulate the reading of the voltmeter PV1 by the power source to set the specified voltage value and measure the effective value of the voltage U x , V, with the voltmeter PV2 and power R n, W, with the wattmeter PW.

7.1.4 Set the voltage corresponding to the larger value of the amplitude of the magnetic induction, and repeat the operations specified in 7.1.2, 7.1.3.

7.2 Determination of the effective value of the magnetic field strength is based on the measurement of the magnetizing current.

7.2.1 At the installation (see Figure 1), the switches S2, S4 are closed and the switches S1, S3 are opened.

7.2.2 Set the voltage U cp or U, V, the remagnetization frequency /, Hz, and determine the values ​​​​of the magnetizing current /, A using the ammeter PA.

7.2.3 Set the voltage to a higher value and repeat the operations indicated in

8 Rules for processing measurement results

8.1 The shape factor of the voltage curve on the winding II of the sample is calculated by the formula

shche U x - effective voltage value, V;

U c p - voltage calculated by formula (6), V.

8.2 Specific magnetic losses P^, W/kg, of a sample from strips or an annular shape are calculated by the formula

where m x is the effective mass of the sample, kg;

R m - average value of power, W;

U\ - effective voltage value, V;

W x , W 2 - the number of turns of the windings of the sample 72; g b g e - see 6.7.

The values ​​-y- and ^ are neglected if the ratio ~ does not exceed 0.2% of -f R m, and

ratio - does not exceed 0.002.

The error in determining the resistance g e should not go beyond ± 1%. It is allowed to substitute a value equal to 1.11 f / cp instead of voltage U x at = 1.11 ± 0.02.

8.3 To exclude the influence of distortions in the shape of the magnetic flux curve on the result of measuring magnetic losses, an adjustment is made based on the fact that the magnetic losses are equal to the sum of the losses for hysteresis and eddy currents, the first value being independent of the distortions in the shape of the magnetic flux curve, and the second being proportional to the square the shape factor of the voltage curve on the winding II of the sample.

8.3.1 If the value of the voltage curve shape factor Af differs from 1.11 by more than ±1%, the specific magnetic losses for the sinusoidal shape of the magnetic flux curve P yjLC9 W/kg are calculated by the formula

^sp.s ^sp I 1 ^d)

UlJJ'

where Rud - specific magnetic losses, W / kg;

A,. - the ratio of specific magnetic losses for hysteresis to specific magnetic losses.

8.3.2 The voltage curve shape factor should be in the range of 1.08-1.16 when measuring specific magnetic losses and 1.09-1.13 when measuring the effective value of the magnetic field strength.

8.3.3 The value of value 04. is selected from table 5.

Table 5

The value a is allowed, calculated from the magnetic losses measured at two values ​​of the shape factor of the voltage curve and constant values amplitudes of magnetic induction and frequency, according to the formula

(Ld ~ La)" ^ \

(*V^i)L,.'