SU86192A1 - Electrical Material Research Device - Google Patents

Description

A device is proposed for the study of electrical materials, in particular for determining the dielectric loss angle and for determining the magnetic properties of materials.

In the known devices for determining the dielectric flux angle, the latter is found by calculating on the basis of two measurements, one of which gives a current value depending on the phase, and the other a current value that does not depend on the voltage applied to the sample.

The aim of the invention is to create a universal device for determining both the dielectric and magnetic characteristics of materials with the ability to directly read the values of measured values on the scale of the dial gauge without additional calculations.

This is ensured by the presence of two parallel branches in the device, connected in series with an alternating current source and a test sample, one of which includes a lamp rectifier and another - a triode (or thyratron), to the grid of which a voltage is applied that coincides in phase with the voltage on the test sample.

The dielectric loss angle is measured on a scale of a meter that measures the ratio of currents in the branches, or at the tip of a voltmeter that measures the difference in voltage drops in two active resistances connected in series with a lamp rectifier and triode.

The ability to determine the magnetic properties of materials is ensured by the presence in the device of two windings serving to place a test sample in them, ii a switch designed to turn on one of the windings in the triode circuit (or thyratron) in accordance with L1 86192-- 2 -. ; hence with an alternating current source, and the other into a power circuit in series with the meter.

FIG. Figure 1 shows the complete electrical circuit of the device; in fig. 2 - part of the scheme used in determining the dielectric loss angle and capacitance; in fig. 3 - part of the circuit, valid when removing the magnetic characteristics.

The complete device diagram shown in FIG. 1, consists of a test transducer T, a three-electrode lamp or a thyratron .y / i, a rectifying lamp L, two identical resistances RI and RZ, connected according to the voltage divider, balancing resistances and Rj, resistances and R-. Phasoregulator, adjusting resistances R and R &, bias resistance, ,,, two magnetoelectric measuring devices: device A n voltmeter, switches // i, // 2, Yaz, I, Pe P and I and test specimens O and 0 Transformer T can be replaceable, partitioned, or divided into two transformers, one of which contains windings for supplying the incandescent lamps and a phase regulator winding, and the other has a high voltage winding for supplying the anode of lamps. The primary windings of both transformers in this case must be powered from a single current source.

All switches, except the switch P, are controlled by one. handle, so they are hereinafter referred to as - "common switch / 7.

To determine tgd (dielectric loss tangent), the common switch I is set to position a and the device diagram takes the form shown in FIG. 2

The current flowing through the test sample Oi splits at point a into two equal parts, one of which flows through the lamp L, and the other through the lamp Lch. A voltage is applied to the grid L of the lamp that coincides in phase with the voltage applied to the sample.

The current / ,, flowing through the lamp L is equal to / i - ;; and the current / g flowing through the lamp 2 is equal to / 2 -, where / is the effective current value. These currents can be passed through the appropriate obmogki logometer magnetoelectric system, which will measure their ratio.

The scale of the logometer can be calibrated directly with the values of tg6. Instead of a thyratron, a triode can be taken, which will increase the reliability of the circuit.

The drawing shows a diagram not with a logometer, but with a conventional voltmeter. This allows the same meter to be used for other measurements described below.

In this case, a resistance R is introduced into each branch L and // 2. On the resistance / there will be a voltage drop, respectively.

Ul .- Rcosff i and 2 - 9 Measuring the potential difference between two points equally equal to the center, we will have: and ..- :: L-a - Ll - -yy (1 - coscpj.

Icosvf

// With a certain degree of approximation, we can assume cos9 tg6.

mf7.Jl (), from tg-fi - 1 - -t

Therefore, after preliminary calibration of the scale, the Ig6 can be determined by direct reading on the scale of the measuring instrument (voltmeter) without additional calculations.

Thus, for measuring tg6, it is enough to put the open switch / 7 in position a, and the voltmeter switch P to position 6i - 62, then read on the scale of voltmeter V.

If switch P is turned to ui-Z2, then voltmeter V will be turned on as an ammeter, with a shunt and it can

measure the capacitance of the sample, Oi, since С s-, where bz is the voltage,

applied to sample Oi. Production of capacitance at a constant voltage (Oz, a voltmeter V can be calibrated in units of capacitance. If it is necessary to measure capacitance C at other voltages, then the true value of capacitance Cn can easily be calculated from

When using a device to remove magnetic characteristics, it is necessary to turn the knob of the knob, its switch I to position b (Fig. 3).

If switch P is set to, then voltmeter V will show the voltage drop LJ in the secondary circuit of the test sample 02 and, therefore, the maximum value of induction in

the tested sample B. „„ ks 4 4V-s-l is the cross section, W is the number of turns of the secondary winding and f is the frequency of the alternating current. Considering them constant, we can put .., Ci,

where C is a constant value. As a result, we get

By supplying a voltmeter to the third scale, you can directly count VU.

Switching switch J4 to position ei-62 and moving the rheostat slider Rj until the arrow of the voltmeter V is on the zero scale of induction B, we get that ammeter A will measure the voltage equal to the reactive component of the voltage drop Cs on the resistance Rs, i.e. t / s R Ismtf, and since the resistance: —nie is a constant value, then / sshf - can be directly measured on the scale of instrument A.

You can calibrate the scale of the device L so that it directly shows not / sincp, but / e / 3, where "and w -

the number of turns of the primary winding and / - Alina average field line.

- 3 - № 86192

, ,

 mx

t. , g, .W, „„

No. 86192- 4 The magnetic permeability of the sample becomes, therefore, calculated, as the ratio of the readings of the two instruments | d -JiM where

/ / e / z1pf there is an instrument reading A.

Based on the results obtained, iron loss can also be determined. To do this, move the rheostat lever / BEFORE the voltmeter V shows B, g again, then device A will show the active component of the voltage drop on R, i.e. U / 5 / sof, and supplying the device A the second scale, you can count f.

Since the loss of iron / ,. U Jcostp -, then, taking measurements at a constant voltage (74, we get /,. Kj, where k U,

a / is readout from instrument A. Thus, by providing instrument A third, with a scale, one can directly measure iron loss.

Subject invention

Claims (3)

1. A device for the study of electrical materials, in which the measurement of the dielectric loss angle is carried out by comparing the active component and the total value of the current passed through the test sample, characterized in that it is composed of two parallel branches connected in series with the AC source and the test sample, one of which includes a lamp rectifier, and the other a triode (or thyratron), on the grid of which a voltage is applied that coincides in phase with the voltage applied to the subject the sample, for the purpose of direct reading of the dielectric loss angle on the scale of the gauge measuring the ratio of currents in branch x. 2. A device according to claim 1, characterized in that active resistors are connected in series with the rectifier and triode in order to directly read the dielectric loss angle on the bar of a voltmeter measuring the difference of the voltage drop in these resistances. 3. A device of claim 1, characterized in that, in order to use it also to determine the magnetic properties of materials, it is equipped with two windings serving to place the test sample in them and a switch intended to turn on one of the windings in the triode circuit (or thyratron) in series with an alternating current source, and the other into a rectifier circuit in series with a measuring device. W № 86192 f 6