SU1234889A1 - Device for measuring arcing time on contacts of three-pole switching device - Google Patents

Abstract

The invention relates to a technique for measuring the arc burning time at the contacts of switching devices. And it allows to improve the noise immunity when testing these devices and to simplify the device. When the switching device contacts are closed, the resistors of the first and second stars included in the same phases flow the same currents, the potentials of the zero points O, and the Oj stars are equal and there is no signal at the output of the voltage sensor. On the control winding 12 of the reed switch 10, the signal is not received, the reed switch 10 is open, therefore the counting device 14 does not work NW W 00 .4 00 00 co

Description

Mot on the fact that the reed switch 11 is closed. When the contacts open, an arc appears on them. Since in all three poles the arc resistance is unequally different in the voltage across the arc in each phase. The zero point 0 of the second star occurs due to the voltage imbalance at its network terminals. A potential difference arises between the zero points of the first and second stars. This voltage flows through the rectifier 7 to the inverting input of the comparator 9. When the input signal exceeds the operating threshold, the comparator 9 is thrown from zero to one and a current flows through the control winding, which leads to closure of herkoI

The invention relates to a technique for measuring the arc time at the contacts of three-pole switching devices.

The purpose of the invention is to increase the immunity during trials of three-pole switching devices and to simplify the device.

Fig. 1 shows a circuit for connecting the voltage sensor of the device to the contacts of a three-pole switching apparatus; in fig. 2 is an electrical circuit of the proposed device for measuring arc time at the contacts of a three-pole switching apparatus; in fig. 3 - vector diagrams of voltage sensor voltages.

In the proposed device, the voltage sensor (Fig. 1) consists of three identical resistors, 1, connected to the first star and connected to contacts 2 of a three-pole switching device on the side of the power source and three identical resistors 3, connected to the second star and connected to pins 2 of a three-pole switching device on the load side 4. The zero points of the first and second arrival are O and 0 of the slope 10. The reed switch 11 is also closed, since its control winding 13 is energized by a milder current from the current sensor 6. As both reed switches are closed, the counting device starts counting “As the contacts open, the current; through them decreases, the voltage drop across the arc increases. When all contacts of the three-pole apparatus are completely opened, the second star and the load 4 are disconnected from the power source, therefore there will be no potential at the zero point of the second star and the output circuit of the voltage sensor will be open. There is no signal at the output. The sensor is missing. Reed switches 1 O and 11 are open, the counting device stops counting, 3.pf-ly, 2il.

shorted to the input clips of the registration unit 5.

When the contacts of the electrical apparatus are closed, the corresponding currents of the first and second stars flow through the corresponding yields of the same magnitude, hence the potentials of the zero points of the stars will be equal and there will be no signal at the output of the voltage sensor.

When the contacts open, an arc appears on them. Since the arc resistance is unequal at all three poles of the apparatus, and at some pole it may not be at all, then. the phase resistance after the first star is also unequal, which causes a voltage imbalance on the second star and a potential difference arises between the zero points of the first and second stars.

When the arc is extinguished, at all three poles the second star and the load will be disconnected from the power source, therefore there will be no potential at the neutral of the second star, and the output circuit of the voltage sensor will be disconnected. Consequently, the signal from the voltage sensor enters the input terminals of the recording unit from the beginning of the arcing to the controller

so until the current is completely shut off by all three poles.

The mutual influence of the phases on the sensor operation is not affected, the interference from the auxiliary switching equipment located close to the apparatus under test is compensated.

The proposed device (Fig. 2) serves to measure the maximum arc time at the contacts of a three-pole switching apparatus in a three-wire three-phase circuit. It includes a voltage sensor on resistors 1 and 3, a current sensor 6, rectifiers 7 and 8, a comparator 9, reed switches 10 and 11 with windings 12 and 13 controls, a counting device 14, an indicator 15.

The voltage sensor consists of six resistor circuits, each circuit being made up of four series-connected resistors. The resistor circuits are assembled into the first and second stars and connected to the contacts 2 according to FIG. 1. The zero points of the first and second stars are connected to the diagonal of the full-wave rectifier bridge 7.

The output of the bridge 7 is connected to the input of the comparator 9, the load of which is connected to the winding 12 controlling the reed switch.

Current sensor 6 consists of three current transformers, the secondary windings of which are connected to a three-phase full-wave rectifier 8 on diodes connected to a winding 13 of a reed switch 11 of type KEM-2.

The reed switches 10 and 11, which form the coincidence circuit, are connected in series and connected to the counting device 14. The comparator 9 is made on a microchip. The signal from the voltage sensor is fed to the inverting input of the comparator 9, and the non-inverting input is energized according to the threshold of the trigger. The counting device 14 is made with digital display.

The device works as follows.

When the switching device contacts 2 are closed, the resistors 1 and 3 of the first and second stars included in the same phases flow through the same currents, therefore the potentials of zero points 0 and 0 stars will be equal and there will be no signal at the output of the voltage sensor. Vector

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The voltage patterns of the first and second stars of the voltage sensor are identical, and are shown in FIG. Behind.

There is no signal on the winding 12 of the control of the reed switch 10, the reed switch 10 times up, therefore the counting device 14 does not work, despite the fact that the reed switch 11 is closed.

When the contacts 2 are opened, an arc appears on them. Since in all three poles the arc resistance is not the same, the voltage across the arc in each phase is not the same in each phase. The zero point zero of the second star occurs due to voltage unbalance at the network terminals. The vector diagram for the case when the arc is lit in three phases is shown in FIG. Zb. A potential difference occurs between the zero points of the first and second stars. This voltage is supplied through the rectifier 7 to the inverting input of the comparator 9. When the input signal exceeds the threshold of operation, the comparator 9 changes from zero to one and a current flows through the control winding 12, which causes the reed switch 10. It is also closed, so As the control winding 13 is applied, the rectified current from the current sensor 6 is supplied. As both reed switches are closed, the counting device starts counting.

As the contacts open, the current through them decreases, and the voltage drop across the arc increases.

The voltage vector diagram for the case when the arc burns in phases A and B is shown in FIG. Sound

When all the contacts 2 of the three-pole apparatus are completely opened, the second star and the load 4 are disconnected from the power source, therefore there is no potential at the zero point of the second star and the output circuit of the voltage sensor is open. The signal at the output of the current sensor 6 is missing. Reed switches 10 and 11 are open, the counting device stops counting.

Claims (2)

1. An apparatus for measuring the arc time at the contacts of a three-pole switching apparatus, comprising voltage and current sensors and a recording unit, each of said sensors comprising two. A semi-period rectifier whose output is connected to the input of the coincidence circuit, the output of which is connected to the input of the registration unit, is characterized in that, in order to simplify the design and increase the reliability of the device in operation, the voltage sensor and the current sensor are common to all poles, and the voltage is made in the form of two stars, each of which consists of resistors of the same rating, the outputs of one star are connected to the terminals of the contacts of the tested switching device, designed to be connected to the source iku power. The outputs of the other star are connected to the terminals of the contacts of the apparatus under test, intended for connecting the load, the common points of each star are connected to the inputs of the two-pole voltage sensor rectifier. 2. The device according to claim 1, which is due to the fact that, in order to increase the reliability of the device in operation by increasing its noise immunity, a comparator is inserted into the voltage sensor, the input of which is connected to the output of the full-wave voltage a mitele, and the output is with a control winding of the voltage sensor reed switch. yjut -СЧОЛ Compiled by N.Malakhova Editor Y. Sereda Tekhred L. Oleinik Proofreader V, But ha Order 2988/54 Edition 643 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab ,, d, 4/5 Production and printing company, Uzhgorod, st. Project, 4