SU989660A2 - Device for protecting three-phase electric installation from phase alternation change and phase break - Google Patents

Description

The invention relates to electrical engineering and can be used in control and automation circuits, in particular for the operational control of the state of a three-phase network.

According to the main author. St. 686117, a device for protecting a three-phase electrical installation against alternation and phase failure is known, which contains a three-phase rectifier connected to the phases of a three-phase network, thyristors, resistors and an actuator of the relay, in which the cathodes of the rectifier diodes are connected to the winding of the actuator-relay through which the connected thyristors are connected to the neutral wire, and the control electrode of the thyristor through the resistor and the diode additionally inserted is connected to the corresponding phase, phase 1.

This device has a limited scope, because when one of the phases fails or the phase alternates, the reacting organ turns off, but it spontaneously switches on again when the normal operation of the supply mains is restored, which creates a danger for the operating personnel. . .

The device is uneconomical, since when one of the phases is broken, despite the fact that the reacting organ is disconnected, the flow of electrical energy continues through the control electrodes of the thyristors of the operational phases.

The purpose of the invention is to increase the operational reliability of the device by excluding self-starting.

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This goal is achieved by the fact that the device for setting a three-phase electrical installation from alternating alternation and phase failure is additionally equipped with a start button and a thyristor connected in series with the main thyristors to the neutral wire, and the start button is connected between the anode and the control of the thyristor electrode.

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FIG. 1 shows a diagram of the device; in fig. 2 is a diagram of the operation of the controlled thyristors of the device.

Claims (1)

The device contains 1–3 three-phase rectifier diodes (A, B, C - mains phases) connected to reacting authority 4, thyristors 5–7 controlling the correctness of alternating phases of the supply mains, thyristor 8 carrying out zero protection, diodes 9–11 , carrying out the isolation of the control switches of the electrodes of the controlling thyridors, resistors 12-14, which limit the current through the control transitions of the thyristors. The button 15 is used to start the device. The device works as follows. After switching on the supply voltage of the controlled network by pressing button 15 on the control electrode, the thyristor 8 supplies voltage from phases A, B and C through diodes 9-11, resistors 12-14 and control transitions of thyristors 5-7. With proper phase rotation, the thyristor 7 control electrode 7 through diode 9 and resistor 12 receives a positive half-wave voltage of phase A, which prepares it for opening and opens the thyristor 8. In this case, the positive voltage to half-wave voltage of phase C diode 10 and resistor 13 the thyristor 6 is prepared by the thyristor 6 and the thyristors 7 and 8 are open in the open state, and the half-wave is positive, but the phase C unlocks the thyristor 5. At the same time, the current flowing from the cathode rectifier group built on diodes 1-3 through thyristors 5- 8 on There is a reaction organ 4, which, when the button 15 is released, remains in the on state, because / in the normal state of the power supply network, the thyristors 5-8 remain permanently on. When the voltage disappears in one of the phases of the monitored network, for example, in phase A, current flow through diode 1 is stopped. This causes a break in the power supply to the thyristor 8, which is closed, and the response organ returns to its original state. At the same time, the flow of current through the thyristor control transitions 5-7 is stopped. If the phase is incorrectly alternated, when the button 15 is pressed, the control electrode of the thyristor 7 (point a of Fig. 2) receives a positive half-voltage of phase A, which prepares it for opening and opens the thyristor 8. At the same time, the positive half-wave voltage is applied to the control electrode of the thyristor 6 In phase C, which prepares the thyristor b for switching on and keeps thyristors 7 and 8 in the on state. But during the flow of the control current of the thyristor b from point a to point p, the positive voltage at its anode is absent m, the thyristor 6 does not open, and the thyristors 7 and 8 are not held in the on state. The reacting organ is not turned on. The device reacting body 4 is turned on and depressed in the on state only with the correct phase rotation and it is turned off when the phase is incorrect power supply. In this case, the useless current consumption in the control circuit of the device does not occur. The proposed device in case of loss, for example, phase C in installations with a 380 V network direction when using thyristors with control current nor 0.3 A saves energy in the order of 0-1 kWh. The control of the correctness of phase interruptions by the network network is carried out continuously, and the reactive organ is switched on again after the restoration of the correct phase alternation of the supply mains, which ensures zero protection and ensures the safety of service personnel. This expands the field of application of the device and improves its efficiency and reliability. Claims of Invention A device for protection of a three-phase electrical installation from - alternation of alternation and break of phases according to aut. No. 686117, characterized in that, in order to increase operational reliability by eliminating self-starting, it is additionally equipped with a start button and a thyristor connected in series with the main thyristors in the neutral wire, and between the anode and the control electrode: . Sources of information taken into account in the examination 1. USSR author's certificate 686117, cl. H 02 H 7/09, 1978. ue.i