SU1471137A1 - Method of measuring electrical parameters of electrical installation groundings - Google Patents

Abstract

This invention relates to electrical measuring technology. The purpose of the invention is to improve the accuracy of measuring the potential distribution at controlled points on the ground surface of a grounding system. For this, a test voltage is applied to current electrodes with a phase shift equal to * 98P / 2 with respect to the main harmonic of the interference voltage. The induced voltage is then integrated over the half-period of the test voltage from the time it is applied. 1 il.

Description

one

The invention relates to electrical measuring equipment, in particular to measurements of the distribution of potentials at controlled points and on the ground surface of a grounding system, as well as the ground resistance of an electrical installation.

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

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

The device contains current electrodes 1 and 2, potential electrodes 3 and 4, voltage measuring unit 5, switching unit 6, power supply 7, current measuring unit 8, switch 9, indicator 10.

The voltage measurement unit 5 comprises a differential amplifier 11, a switch 12, an integrator 13, a diode 14. The switching unit 6 comprises a band-pass filter 15, a pulse shaper 16, a coincidence block 17, a phase switch 18, an interrupter 19, a single-oscillator 20. Power supply unit 7 contains a storage unit 21, a power source 22. The current measurement side 8 comprises a dividing unit 23, a memory unit 24, a current sensor 25.

The electrode 1 is connected to one of the H) 1 inputs of the accumulator 21, the second output of which is connected to the electrode 2 through the phase switch 18 and the current sensor 25 to the current sensor 25 through memory unit 24 connected to the dividing unit 23, the second input of which and the output is connected to one of the torus 9 groups, the movable contact of which through the indicator 10 is connected to the common bus of the device. The second input block

four

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23 divisions are connected with a movable contact of the second group of switch. 9, the fixed contacts of which are connected to the output of the integrator 13 and the cathode of the diode 14,

The device works as follows.

To measure the electrical parameters of the earth ground, the potential electrodes 4 and 3 are located in the control point 1, and the toe electrode 2 is located at a certain distance from the earth conductor outside the zone of current spreading.

The switch 9 is set to the position shown in the drawing.

If there are currents in the measurement zone on the electrodes 3. and 4, an interference voltage is applied to the input of the voltage measurement unit 5 and then through the switch 9 to the indicator 10, which indicates the voltage level of the voltage.

After that, the switch 9 is switched to position II and the breaker 19 is pressed, and the square signal is received at the second input of the coincidence unit 17. At the same time, the voltage induced on the electrodes 3 and A enters through the F1-mtr 15J separating the main harmonic of the interference with the conventionally extended phase angle of the phasf, on the driver 16, in which

0

five

0

about

harmonics in, at an angle ;; . Wherein

An aggregate voltage (test signal and interference) is induced on electrodes 3 and 4 and is memorized in integrator 13, the key 12 of which is activated half a period of the main harmonic of the interference voltage.

The integral value of the truncated positive half-sine wave of the main harmonic of the interference voltage in absolute value is equal to the negative half-sine wave, therefore the total value of the main harmonic for the half-period as a result of integration is zero.

Similarly, the even-numbered harmonics are eliminated. The effect of odd harmonics is reduced by - times, where K - K

The odd-numbered harmonic number is higher. Thus, integration is subjected to

a signal consisting of test voltage, even and odd pp. ar- monic voltage interference.

If the interference voltage is not present, the phase switch 18 opens in the same way as described above by pressing the chopper 19 and setting switch 9 to position III. In this case, the inputs of the block I7 matches simultaneously

By the torus, the signal is amplified and transformed, with a pulse coming from the output of one., - - SeJt-1-1-t / -. , p ...- .. about LLTT. . .

is in form from sinusoidal to rectangular with a shift of the output pulses relative to the input

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angle 2,

Thus, at the first input of block 17, the coincidence arrives a series of rectangular and bulbs with phase

/ V

(P) relative to the main phase

harmonics eg; This is interference. I

At the time of coincidence in time and at the inputs of the block of 17 matches, keys 12 and 18 receive a single direct pulse from the phase

40

the vibrator 20. The voltage from the output of the integrator 13 is fed to the second input of the Delech block 23, which also receives a voltage proportional to the value of the test current from the output of the current sensor 25.

The deviation of the arrow of the indicator 10 corresponds to the ratio of the magnitude of the test voltage (without the voltage of 1) interference to the value of the test current.

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Claims (1)

Invention Formula A method for measuring electrical parameters of earthing devices of electrical installations, in that test voltage is applied to current electrodes and electrical parameters are measured by integrating the induced voltage, which, in order to improve accuracy, (tp- -). There is a dd circuit passing the test current — the discharge circuit of the accumulator 21. The discharge current pulse is in the form close to a sinusoid, which is provided by the parsheters of the LC circuit of the accumulator 21 and electrode 1, and lags behind the main “-SeJt-1-1-t / -. , p ...- .. about LLTT. . . 40 the vibrator 20. The voltage from the output of the integrator 13 is fed to the second input of the Delech block 23, which also receives a voltage proportional to the value of the test current from the output of the current sensor 25. The deviation of the arrow of the indicator 10 corresponds to the ratio of the magnitude of the test voltage (without voltage), to the magnitude of the test current. 50 55 Invention Formula A method for measuring electrical parameters of earthing devices of electrical installations, which means that the test voltage is applied to the current electrodes and the electrical parameters are measured by the method. the integration of induced voltage, characterized in that, in order to improve accuracy, By applying the test voltage, the phase of the first harmonic of the interference voltage is measured, the test voltage of the industrial frequency is supplied with a phase shift equal to / 2, relative to the main harmonic of the interference voltage. / U / ////// /// /// /// /// /// /// / / / V and the integration of the induced voltage is produced for a time multiple of an odd number of the half-period of the test voltage since its passage through zero. p F: , /