RU2745808C1 - Method for remote diagnostics of time intervals of contacts of three-phase switches in operating electrical networks - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to measuring the parameters of high-voltage and low-voltage three-phase switches in operating electrical networks, in particular, the timing of the closing and opening of contacts. The technical result is achieved by the fact that a method is proposed for remote diagnostics of the time intervals of contacts of three-phase switches in operating electrical networks, characterized by the fact that a tripod is installed in front of the switches at an insulating voltage distance, a magnetic antenna in the form of an inductance coil is fixed on it, the axis directed perpendicular to the terminals of the three-phase switch, in which active operating currents of the phases create the magnetic field strength and magnetic flux, connect the output of the magnetic antenna to the input of the analog-to-digital converter of the digital oscilloscope, the output of the latter is connected to a computer, on which, according to a special program, the voltage changes proportional to the currents of the electric network are visualized as oscillograms, and when switching the contacts of the switch, pulse harmonic processes are distinguished, according to the maximum values ​​of which the time intervals of the divergence of the contacts of the switch are recorded.

EFFECT: improves the performance and increasing the accuracy of processing the results of measuring the temporary parameters of contacts when switching three-phase switches in operating electrical networks.

1 cl, 4 dwg

Description

The invention relates to the electric power industry for non-contact diagnostic monitoring of the time intervals of contacts of high-voltage and low-voltage three-phase switches, in particular, the difference in timing of closing and opening of contacts of switches installed in operating electrical networks.

The invention is intended for measuring the parameters of switches in operating electrical networks for the purpose of timely removal of the switches from the electrical network for repairs upon detection of faults in their contact system, exceeding in magnitude the normalized parameters regulated by RD 34.45-51.300-97. "Scope and norms of testing electrical equipment", "Operating instructions for circuit breakers", as well as during commissioning tests.

A device is known for determining the timing of the closure of movable contacts of switches with fixed contacts based on a simple circuit with incandescent lamps published in the "Collection of methodological manuals for monitoring the state of electrical equipment" (section 4 "Methods for monitoring the state of switching devices"), M, ORGRES, 1997, from. 52.

The device contains a constant voltage source and three lamps connected in series to the circuit of each phase of the contact system of a high-voltage switch.In this device, the timing of the closure of movable contacts with fixed contacts is carried out indirectly by the difference in linear displacements of movable contacts in different phases in the switch chamber without oil and is slowly manually turned on switch using a lever or jack. The fixation of the contact of the contacts in each phase is carried out by the operator by lighting up the corresponding lamps and gradually marking the positions of the guide tube on the insulating rod with a pencil. Then the ruler manually measures the positions of the moving contacts.

The measurement accuracy in the above method depends to a large extent on subjective factors. The device is not automated and it technically lacks the ability to determine the time of switching on and off the switch, as well as to identify contact bounce.

There is also known a method for the diagnosis of electrical switching devices, which is based on the formation of a periodic oscillatory process using an electromagnetic vibrator, the formation of a diagram of this process as a function of the position of the moving contact of the apparatus and the determination of the values of the speed of this contact in the characteristic points of the trajectory of its movement along the image length of the periods of oscillations on diagram. This method is described in the "Handbook on the power supply of industrial enterprises.", In the book. 2, "Technical information about the equipment" Under total. ed. A.A. Fedorov and G.V. Serbinovsky .. - M .: Energiya, 1974, p. 522].

This method is the closest to the claimed in technical essence and is taken as a prototype. However, it has the following disadvantages:

a large amount of preparatory and restoration work, as well as the need to drain the oil from the tank before testing and then fill it when testing some types of switches); the need to dismantle from the cells of complete switchgears (RKU) suspended switching devices for the installation of a rod with a holder for diagram paper;

the need to process vibrograms manually and the difficulties of its automation;

the impossibility of using the method for diagnostics of high-speed switching devices having an on or off time not exceeding several periods of the signal display on the vibrogram, due to an unacceptable increase in the measurement error.

The technical result of the proposed method is to improve the performance and improve the accuracy of processing the results of measuring the time intervals of contacts when switching three-phase switches in existing electrical networks to monitor their state of operability in real time.

In the proposed method, the principle of remote diagnostics is used, since the state of the switches is monitored in working electrical networks, that is, without turning them off.

The technical result is achieved by the fact that in the method of remote diagnostics of time intervals of contacts of three-phase switches in operating electrical networks when switching contacts of three-phase switches, currents of three phases A; IN; FROM; create pulse-harmonic transient processes, in the surrounding space, in the plane of the cross-sections of conductors, according to Ampere's law, a magnetic field strength arises, which is perceived by a magnetic antenna, represented by a turn coil of inductance, the axis of which is perpendicular to the power conductors - contacts. The antenna is mounted on a tripod and its output is connected to a single-channel input of an analog-to-digital converter (ADC) of a digital oscilloscope for recording oscillograms, which in turn is connected to a computer, which allows, using a special program, visually in the form of an oscillogram to determine the general nature of changes in the magnetic field strengths presented voltage values, with selected maximum values of impulse-transient processes from each of the three switchable contacts of the switch, according to which the time intervals between the maximum values of the variable parameters of the processes of opening or closing the contacts of each of the phases A are determined with high accuracy; IN; From an operating three-phase switch and, in case of exceeding the permissible temporary discrepancies of contacts, they record its state and the possibility of its further operation.

Drawings explaining the method are presented on:

Fig. 1 is a block diagram that implements the method;

FIG. 2 - view of the cell of a complete switchgear with a three-phase switch and a remote magnetic antenna;

FIG. 3 - oscillogram of time intervals between contacts when the switch is closed with separated transient processes;

fig. 4 - oscillogram of time intervals between contacts when the switch is closed with partially superimposed transients.

The proposed method for remote diagnostics of time intervals of contacts of three-phase switches works as follows: in operating electrical networks when switching contacts of three-phase switches 1 (Fig. 1) currents of three phases A; IN; With create pulse-harmonic transient processes, in the surrounding space, in the plane of the cross-sections of the conductors, according to Ampere's law, a magnetic field strength arises, which is perceived by a magnetic antenna, represented by a coil inductor 2 (Fig. 2), the axis of which is perpendicular to the power conductors - contacts. The antenna is installed on a tripod at an insulating voltage distance from conductors with operating currents of three phases A; IN; FROM; for example, for 10 kV - 0.12 m; 35 kV - 0.29 m; 110 kV - 0.7 m, etc. [Electrical Installation Rules. Chapter 4.2. Switchgears and substations with voltage above 1 kV. Order of the Ministry of Energy of Russia dated 20.06.2003 No. 242]; the output of the magnetic antenna 2 is connected to a single-channel input of an analog-to-digital converter (ADC) of a digital oscilloscope 3, for example, of the Hantek DSO5202P type, 200 MHz, with USB 2.0 for recording oscillograms on a flash card or for communication with a computer 4, on which, using an installed on it, a special program visually in the form of an oscillogram determines the general nature of the change in the strengths of the magnetic fields, represented by the voltage values, with the selected maximum values of the pulse-transient processes from each of the three switched contacts of the switch (Fig. 3, 4), which allows with high accuracy with a single channel measurements of three-phase processes determine the rational frequency range for a magnetic antenna and a digital oscilloscope - up to 200 MHz at a harmonic component frequency of 25 kHz of transient processes when switching contacts, determine the time intervals between the maximum values of the variable parameters of the processes of opening or closing contacts each oh of phases A; IN; From working three-phase switches (Fig. 3; Fig. 4) and in case of exceeding the permissible time discrepancies of contacts such as non-full-phase modes, burning of contacts, etc., defined in RD 34.45-51.300-97 "Scope and standards of testing of electrical equipment". 6th edition, with amendments and additions as of 01.03.2001. - M .: Publishing house NTs ENAS. 2004, p. 30, or, for example, in accordance with the requirements of the "Operating Manual 2GK.256.072 RE of the VVM-SESH-3-10 type vacuum circuit breaker", for which the difference in timing of touching the moving contacts for three poles is allowed no more than 2 ms, which when comparing the standardized values with oscillograms similar to FIG. 3, 4; register the need for timely decommissioning of the switch for repair to adjust the contacts of the switch or replace it.

Claims (1)

A method for remote diagnostics of time intervals of contacts of three-phase switches in operating electrical networks, characterized by the fact that a tripod is installed in front of the switches at an isolation voltage distance, a magnetic antenna in the form of an inductance coil is fixed on it, the axis is directed perpendicular to the terminals of a three-phase switch, in which the operating currents are phases create a magnetic field strength and magnetic flux, connect the output of the magnetic antenna to the input of an analog-to-digital converter of a digital oscilloscope, the output of the latter is connected to a computer, on which, according to a special program, it is visualized in the form of oscillograms of voltage changes proportional to the currents of the electrical network, and when switching the switch contacts pulse-harmonic processes are distinguished, according to the maximum values of which the time intervals of divergence of the switch contacts are recorded.

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