SU1302226A1 - Method of measuring magnetic characteristics of materials - Google Patents

Abstract

The invention relates to the field of electrical measurements and can be used to measure the complex magnetic permeability of materials in electrical and radio engineering. The aim of the invention is to improve the measurement accuracy. To achieve this goal, a sample of the material is alternately placed in the electric field of the capacitors of the transverse arms of both T-circuits and the increments of the capacitors of the counting capacitors are determined. Then the sample is placed in the magnetic field of inductance of the transverse arm of the second T-chain and the increment of the capacitance of the reading capacitors is determined. A device for implementing the proposed method contains a resistor 1 and a capacitor 2 s (L loo o | S ISD o P5

Description

1302226

the longitudinal arm of the first T-circuit, the reading capacitor 3, the sample connecting capacitor 4, the inductance coil 5 of the first T-circuit, the sample connecting device 6, capacitors active loss resistance 7, capacitors 8 and 10 of the longitudinal shoulder of the second T circuit, generator

one

The invention relates to the field of electrical measurements and can be used to measure the complex magnetic permeability of materials in electrical and radio engineering.

The purpose of the invention is to improve the measurement accuracy.

The drawing shows a diagram of the device that implements the method.

The device contains a resistor 1 with the value R of the longitudinal arm of the first T-circuit, the capacitor 2 of the longitudinal arm of the first T-circuit with capacitance C ,, connected at one end to the resistor 1, the reference capacitor 3 of variable capacitance C,; mountain condensation 4 sample connections with the capacitance Cn, the coil 5 of the inductance of the first T-circuit value

at

converter 6 - device

connect the sample to the coil 5 inductance with the value of inductance and connected in series with

Ooh

the inductor 5, the resistance 7 active losses in the capacitors 3 and 4, the Converter 6 and the inductor 5 value of g. Bipolar circuits (capacitors 3 and 4, inductance 5, resistance 7 of active loops) are interconnected in parallel, with one end of their connection connected to the junction of resistor 1 and capacitor 2, and the second one to the case, i.e. grounded In addition, the device contains a capacitor 8 of the longitudinal arm of the second T-circuit of size C, connected at one end to the capacitor 2 and to the potential output of the generator 9, a capacitor 10 of C of the longitudinal shoulder of the second T-circuit connected to the second end of the resistor 1 and potential9 , indicator 11, readout capacitor 12 and inductance coil 14 of the second T-circuit, sample connection capacitor 13, sample connection device 15 to inductor coil 14, active loss resistance 16 in epemat x 12,13,14 and 15 circuits. 1 il.

The social terminal of the balance-voltmeter indicator 11 (the low-potential outputs of the generator 9 and the indicator 11 are grounded), the reading capacitor 12

5 variable capacitance Cd of the second T circuit, capacitor 13 for connecting the sample with capacitance Spd ,,; coil 14 of the inductance of the second T circuit of Lg, converter 15 -

0 (device connecting the sample to the coil | inductance 14 with the value b. In series with the coil 14 inductance, the resistance 16 active losses in two-pole:

5 capacitors 12 and 13, inductance coil 14 and converter 15 with gq. Bipolar networks are connected to each other in parallel and form the transverse arm of the second T-chain,

0 and one end of their connection is connected to the junction of capacitors 8 and 10, and the other is grounded.

The device works as follows.

five

0

five

In the double T-bridge, with the initial balance, minimum conductivity at the operating frequency ts between the generator 9 and indicator 11 is achieved by changing the values of the elements of the transverse arms of both T-chains, i.e. capacitor 3 and inductance coil 5; the capacitor 12 and the coil 14 inductance, corresponding to the balance equations of the bridge:

Co l

 - C, - C ,. With ,, ,, gn)

40

l-csga.

(one)

c, (1 .o 2 | o c, s

(2)

where R is the value of the active conductivity of the resistor 1, Cg is the reactive conductivity of the resistor 1, which is always the case and is neglected in the known method. When a sample of the material is introduced into the electric field of the capacitor Spa, a change in its conductivity occurs, since the dielectric constant e and the loss tgS of the sample cause a change in the field of this capacitor, i.e. its capacitance C, q and conductivity gxa, which leads to the imbalance of the bridge. The balance of the bridge is restored by varying the capacitance of the counting capacitors 3 and 12 per lCD and DC, respectively. Then the values СХР and gKq "3 of equations (1) and (2) can be expressed:

Xq

Q

  --8хс, Сд „- A-gxo -, (3)

five

..L iIT- bcd

Ss 1 .u 9 |

about s

a - t-

When the sample material is subsequently introduced into the electric field of the capacitor Cqft of the same sample, it causes a change in its capacitance Sy and conductivity, which leads to imbalance of the bridge, and when the balance of the bridge is reached by changing the capacitance of the counting capacitors 3 and 12 - the balance is restored. Then the values of and from equations (1) and (2) can be expressed:

 one

gi (1

. С, с2

ys

Bq

AT

in j

5i

where a Cg / g, b.

Solving Eqs. (3) - (6) with respect to A and B, we obtain expressions that allow us to determine the values of the associated constant values of the elements of the missus, taking into account the reactance R of the longitudinal arm resistor 1 at the operating frequency, taking into account the reactance of its device connect:

yscd

 Ce.bC, j, - (uC;, - uCea)

, 2 С, „В 1. . (7)

, - (ÑСд, -ь.Свь) 2

Upon subsequent placement of a sample of material with magnetic permeability “and loss of tgujij in the magnetic field of inductance L of transducer 15, the active and reactive conductivity of bridge inductance Bd-14 changes by b and q, respectively. This leads to imbalance of the bridge, which is restored by changing the capacitance of the reading capacitors 3 and 12, respectively, by the value of lds,. Then g j, g and bxa can be expressed by these increments and from equations (1) and (2) and taking into account expressions (7):

g ".v ,,.

° ha

T + u A w (bC ...- Ag, a).

35

40

45

50

Subsequent placement of the same material sample into the magnetic field of inductance Log Converter 6 causes a change in the active and reactive conductivity of coil 5 of the inductance of the bridge L by the value of g, g and. This leads to imbalance of the bridge, which is restored by changing the capacitance of the counting capacitors 3 and 12, respectively, by the value of LSv and LSD. Then, from equations (1) and (2) and taking account of expressions (7) and the obtained values of the capacitance increments of the capacitors, it is possible to determine b and (); (ten)

1 V

SXB R BQ

(eleven)

Taking into account the transforming properties of the lines used as coils 5 and 14 of inductance, (L and b), constituting components of the specimen

51302226 6

(8), (9) and (10), (11) are determined by the second cases of placing the sample through the resulting increments of the capacitance of the material in a magnetic field of inductive-reading capacitors in the first and second respectively

g g lI ". .

gna gxa .Ц „

(12) i.

Y -ctgft - xa.Ie. aLiliStsAlal00 o v + h

& XOI t

(13)

 (14)

exe hb

Y. cts B - i .. fb)

06 PC t-B „5 .. K2

6x6 (15)

where / jo y

.one

oa

and fb

  f (is the working wavelength 06 wave conduction of the lines of induction coils 14 and 5, respectively;

- the length of these lines. Equating in pairs (12), (14) and (13), (15) we obtain two equations, when Solving for Relative and Stroke and YO, we obtain expressions for their determination through the increments of the capacitance of the reading capacitors

mt - S4mn

Od

. Y qm - np ° am -

qm - np

where m is Siu - i- (i + ctg peEa) i n

-xa ":

i- (uctg | 3 e);

g

xe xe

ib-b: V "--i: Vtf-.

Sxa "

b

ixB- ° M5

 (1 + ctg /, j) -, s ctg PO r “. .

The substitute values obtained for Yjpg and YOU are respectively equal to

i-f (n and jJCLD n I.

(12) - (15), determine the values of the compounding constants of the sample, from which the formulas are calculated from the formulas;

50

"

B + g

or

 Xsft. “.2.v.

na

fW

p that tgSn. Sit

paOftt,

g r-b b; 55

(17)

(12) i.

tsAl

s), 25

ZO

35

40

-.

M5

50

55

Thus, by measuring the sample of the material in the first and second arms of the bridge, it is possible to determine the wave conductivity of coils 5 and 14 of inductance (B and L) at the operating frequency taking into account the transient resistances of devices connecting them to the bridge and converter to the line. This increases by 10-20% the accuracy of measuring the magnetic characteristics of materials, since the line parameters are determined experimentally during the measurement, i.e. in real terms.

Claims (1)

Invention Formula Method of measuring magnetic properties of materials c. using a double T-bridge, concluding that they certify the bridge, place a sample of the material in the magnetic inductance field of the transverse arm of the first T-circuit and determine the increments of the capacitances of the reading capacitors of the transverse arms of both T-circuits, calculate the magnetic characteristics of the material using increment of capacitance characterized in that, in order to improve measurement accuracy, a sample of the material is alternately placed in the electric field of the capacitors of the transverse arms of both T-circuits, the increments of the capacitances are determined capacitors, then a sample of the material is placed in the magnetic field inductance of the transverse arm of the second T-chain and the increments of the capacitance of the reading capacitors are determined.