SU1677659A1 - Method of measuring two-terminal rc-network parameters - Google Patents

Description

one

(21) 4399153/21

(22) 03/29/88

(46) 09/15/91. Bul №34

(71) Chita Polytechnic Institute

(72) A.G.Mashkin and A.V. Kudr vtsev (53) 621.317.70803 (0888)

(56) USSR author's certificate N 892347.kl G 01 R 27 / 02,1979

(54) METHOD OF MEASURING PARAMETERS OF RC-TWO-PLANET

(57) The invention relates to electrical measuring equipment and can be used to determine the properties of complex dielectric systems and electrical insulating structures, including cables, power capacitor batteries, electric machines and apparatus, rocks, etc., as well as to control the state of the isolators. electrical cable networks, direct current networks, cable lines,

in particular, to determine the ability of an insulation to change properties under the simultaneous action of a combined constant alternating voltage. The aim of the invention is to provide measurements of RC parameters of two-port networks with absorption properties. The input voltage of the studied RC two-port network is supplied with varying voltage and the total leakage current and the active component of the total leakage current are determined, which determine the desired parameter as variable voltage a rectangular-shaped alternating voltage, the active component of the total leakage current is measured by the magnitude of the effective value of the first harmonic, the varying voltage, the measurement is performed additionally when exposed to a constant voltage, as well as a combined constant and variable Zil

WITH

with

The invention relates to electrical measuring equipment and is intended primarily for determining the properties of complex dielectric systems and electrical insulating structures, including cables, power capacitor batteries, electric machines and apparatus, rocks, etc., as well as to monitor the state of electrical insulation cable networks, DC networks, cable lines, in particular, to determine the ability of the insulation to change properties with the simultaneous action of the combined constant AC voltage and

The purpose of the invention is to improve the accuracy in measuring the parameters of RC two-terminal networks with absorption properties

Fig. 1 shows a functional electrical diagram of a device for measuring parameters of an RC two-port device implementing a method of measuring parameters of an RC two-pole device, Fig. 2 shows timing diagrams illustrating the operation of individual units of the device; in FIG. 3, a replacement circuit of an RC two-pole device with absorption characteristics, where I is the total leakage current, 1a, is respectively active and the reactive component of the total leakage current, 1SKv is the current through wire

Xi

Vj

I abs, Icr - the absorption and capacitive components of the bias current 1CM, 1AABs, Trabs - active and reactive components of the absorption current, ROM - the ohmic resistance of the two-pole device, the inverse of the through conduction G NACSi,), - the resistance to absorption current, the inverse of the active conductivity to the absorption current of Ga6c (U), Ca6c (LL), Cr is the absorption capacity and geometric capacity of the two-pole, respectively. Resistance and active conductivity of a two-pole device is determined accordingly.

RHS -

Re

Ra6c

ROM Ra6c

D ROM R a6c (y

ROM b abs ()

Cyz Ga6c + G

u / r2 + 1

+ G;

C, m () + C

SizN2 2

Utt + 1

A device for measuring RC-two-pole parameters includes a generator of 1 rectangular sign-alternating pulses, a dividing filter 2 at a constant current, a two-terminal 3, a resistor 4, a pulse amplifier 5, an active filter b according to the first harmonic of rectangular pulses, a measuring rectifier 7, converters 8.1 , 8,2 voltages per code; blocks 9.1, 9.2 input and output; 10 DC source; AC separation filter 11, resistor 12, DC amplifier 13, memory block 14, arithmetic logic block 15 subtraction, recording block 16, generator turn-on key 17, switch on DC-source switch 18, recorded-value switch 19.

The generator 1 is connected through a filter 2 to an RC two-port 3, the second input of which is connected to the common bus through the switch 17 and the resistor 4 to the common bus, the output of the switch 17 is connected to the input of the amplifier 5, the second input of which is connected to the common bus. The output of amplifier 5 is connected in series with filter 6, rectifier 7, sampler 8.1, block 9.1, first input of block 14. Source 10 output is connected via filter 11 to RC two-port input 3, as well as via switch 18 and common bus resistor 12 . The output of the key 18 is connected to the input

amplifier 13, the second input of which is connected to a common bus. The output of the amplifier 13 is connected in series with the converter 8.2, unit 9.2 and the second input of the unit

14. The outputs of blocks 9.1,9.2 are connected in series with the first and second inputs of block 15, switch 19 and block 16.

The outputs of the converters 8.1, 8.2 are connected to the second and third inputs of the switch 19,

According to the prototype method, the value of the non-active, and ohmic resistance of the two-pole network is to be measured (since the relaxation component of the leakage current is

5 is associated only with a great relaxation capacitance without losses), if the measurement time is chosen at least five times longer than the current decay time of the absorber on the front and cut sections of the voltage pulse, otherwise the apparent ohmic resistance value, the value of which is random in the transition from one

5 measurement object to another. When using a known method for measuring the absorption capacity of objects with a large value of the tangent of dielectric loss, the value of the measured

0, the capacity will be determined with a large error up to complete uncertainty, and thus this measurement will have practically no informative value for determining the parameters and properties of RC two-port networks with absorption characteristics.

According to the invention, in addition to the magnitude of the ohmic resistance (conductivity), which characterizes the conductive properties

0 of the two-pole and determines the active losses from the transfer of free charges (ohmic losses), the amount of active resistance to the absorption current that characterizes the dielectric properties of the two-pole and determines the active losses from different types of low-frequency migration polarizations (dielectric losses), as well as the magnitude of the active resistance, which determines all the active losses in a two-pole network when operating at alternating voltage, which are defined as under the action of a single variable th, and the combined voltage. This is due to the fact that when acting on an RC bipolar with the absorption characteristics of a sinusoidal voltage with a circular frequency w and an amplitude U, an active current will flow through it at a value of one alternating and combined voltage

+ 1

la (-) u

/ So t2 wz2

ALT (D + 1

+ G

+ G)

where S, S (-) is the initial value of the conductivity without and under constant voltage, g, c-) is the constant decay time of the absorption current without and under constant voltage; G is the through-conduction, the inverse of the ohmic resistance of the two-port G 1 / R0M. This current is determined by the two components 1a 1aabs + 1scv; Ia () Jaa6c (-) + JCKB, where Taabs, 1aabs (-) is an active component of the absorption current and at a constant voltage; | Well - through conduction current.

Therefore, by the active component of the absorption current, it is possible to judge the active resistance to the absorption current, by comparing the values of RABs and NABs (-) of the control action of direct current

Ra6c U / laa6c; Ra6c (-) U / iaa6c (-)

according to the magnitude of the current through conduction - about the ohmic resistance of the ROM U / ICKB.

A device for measuring parameters of an RC two-pole device operates as follows.

The square-wave alternating voltage pulses developed by the square-pulse generator 1, after turning on the key 17, are supplied through a splitter filter 2 to the input of the measured RC two-port Z. A voltage proportional to the total leakage current of the RC-two-pole 3 is applied to the input of the amplifier 5.

U kll (Se l1b + G),

where t is the decay time of the absorption process; k is a constant determined by the parameters of the separation filter 2 and resistor 4; U is the amplitude of the rectangular pulses of the generator 1. From the output of amplifier 5, the inputs of the active filter 6 of the first harmonic are supplied with an increased voltage proportional to the total leakage current of an RC two-pole device:

Us kiU (G),

where ki is a constant determined by the parameters of the connecting filter 2 and amplifier 5. In this case, the output of the active

filter 6 of the first harmonic is formed sinusoidal voltage with amplitude (figure 2):

5i / 2ft / rt

U6 4k2U / (Se t / 6 + G) sin (27rft) dt

 4k2U (V th / V-M

t / e + fG

with /

1 / 2f

where ka is a constant determined by the parameters of the connecting filter 2, resistor 4, amplifier 5 and active filter 6. 15 In case 2f, then

it -4k2U /,. U6 - / + s

 Wr + 1

Therefore, for specific measurement conditions, when k2 and U are constant, the alternating voltage amplitude Kb is determined by the active conductivity of the two-port RC.

The measuring rectifier 7 rectifies and is formed from a sinusoidal signal with an amplitude Ue constant, the value of which is proportional to the active conductivity of the RC two-pole:

., 4 k2 k3 U r U- -oiz

I

or

U4 k2 U l: 4 k2 U

Siz - Sy

40 rA6k3 4k2U

constant

Parameters of straightener 7.

The constant voltage generated by the measuring rectifier 7 is supplied to the input of the transformer 8.1.

5 code voltage. From the output of the converter 8.1, the pulse train is fed to the input of the recording unit 16, through the switch 19 of the recorded values. After achieving a stable Ces reading on the unit

By registering using the I / O unit 9, the magnitude value is entered into the memory unit 14. Then, a DC source 10 is connected to the measured RC two pole 3

5 AC filter 11 with key 18. The voltage taken from resistor 12 is fed to the input of the DC amplifier, proportional to the through current and absorption current of the leaks, and after amplification by amplifier 13 to the input of the converter 8.2

the voltage in the code receives a voltage that is proportional to the magnitude of the ohmic (through) conductivity G of the two-port 3:

Ui3 k4l) - (Se -Sh G)

where U is the voltage of the DC source; k4 is a coefficient depending on the parameters of the DC 10 source, resistor 12 and amplifier 13. Changing the parameters of the above elements, achieve equality M 1 / U-. The value of Se t t becomes very small compared to G. The pulse packet from the output of converter 8.2 is fed to the input of registration unit 16 through switch 19. When a constant G is reached at input 16 of registration with input-output unit 9.2, the value of G is entered into the second cell of the memory block 14, then through the input-output blocks 9.1,9.2, the values of Ces and G are output to the inputs of the arithmetic logic block 15 of the subtraction, and the result of the subtraction is output through the switch 19 to the input of the register 16, which displays Sabe value, then, after erasing, in the first cell of the memory block 14, the value of Ces is entered, the value of CES (-), which, when the switch 19 is switched to registering CPS values, is displayed on the register 16, and when CES (-) is output, output 9 to the arithmetic logic unit 15 subtracting and switching the switch 19 to register the Sabe value on the registration block 16 displays the value Ga6c (-) Compared the values of Sabe and Sabs (), one can judge the control action of the constant voltage on the quality of the R parameters C-two-port. If C & C, then the control action of a constant voltage can be judged by comparing Ces and Ces (-).

When implementing the invention, it is possible to determine the non-linear dependence of the active parameters of an RC-two-port network on voltage and frequency, a unipolar effect, and to evaluate the effectiveness of controlling the DC voltage, depending on polarity, on the quality of the insulation. For example, by changing the amplitude of the voltage of the generator of rectangular pulses from 0 to

Umaks it is possible to find the dependence of the active parameters on the voltage Siz (s). Ga6c (U) and G (U), as well as GM3 (-XU), Ca6c (-) (U).

Claims (1)

The voltage generated by the generator 1 can be varied both in amplitude and frequency, and the frequency of the active filter can be varied at the same time. It is also possible to regulate the magnitude of the voltage of the direct current source 10 and change its polarity. Claim method for measuring RC parameters of a two-port device, including applying a variable voltage to the input of the studied RC two-terminal device and measuring the total leakage current, the active component of the total leakage current, and determining it with the aim of improving the accuracy when measuring RC-two-port parameters with absorption properties, the alternating sign voltage of a rectangular shape is used as a variable voltage, the active component is measured by The leakage current is measured by the magnitude of the effective first harmonic value of the varying voltage, and the active component of the total current Ja (-) is additionally measured; 1c (+) leakage when the two-terminal RC under test is fed to the input parallel to the changing voltage of the dc voltage, respectively, negative and polar polarity, and through the damping time of the absorption process, the component of the active component of the total leakage current — 1Sq pass-through conduction at the input of the studied constant-two-pole RC and determination of the active component CURRENT 1abs, 1abs (+); 1abs (-) absorption of CO corresponding to full currents 1a, respectively; 1a (+); a (-) by formulas 1a — the component of the total leakage current is active; 1abs 1a - 1scv; 1aabs (-) 1a (-) - 1skv, Iaa6c ((+) - JCKB, moreover, the frequency F of the following pulses of the alternating pulsed voltage is selected from the condition F-k-, where it is constant for the time of absorption current decay. LI a one ten J YU- tf Sh-pm. v Vstf V9 & & t Zj I 6.1 M 7D I 15 M4 tr / Phys. 1 FIG. Z J Icn hell Gabs OM Rrtcfu) r Cr T Iq. 0t / aJ Icr 7 rabs