RU2761987C1 - Automatic re-activation device - Google Patents

Abstract

FIELD: electrical engineering.SUBSTANCE: invention relates to electrical engineering, namely the protection of power supply devices from short circuit and providing uninterrupted power supply of automation actuators during transient electrical processes. The device contains a series-connected terminal “Input”, the first converter, normally closed fixed and movable contacts of the first switch, the terminal “Output”. The second converter is connected between the fixed open contact of the first switch and the “Common” terminal. The high-frequency current source is connected to the fixed open contact of the first switch through the normally closed contacts of the second switch. The control inputs of the first and second switch are combined and connected to the output of the D-trigger. The information output of the first and second converter is connected to the input of the first and second comparator, respectively, the input of the reference voltage of each of which is connected to the first and second reference voltage source. The output of the first comparator is connected to the input of the pulse generator, the output of which is connected to the input of the D-trigger. The first input of the logic element 2AND is connected to the output of the initial state setting circuit, the input of which is connected to the output of the power source. The input of the pulse expander is connected to the output of the second voltage comparator, and the output of the pulse expander is connected to the second input of the logic element 2AND.EFFECT: ensuring the protection of the device from false triggering.1 cl, 2 dwg

Description

The invention relates to the automation of power systems and can be used in the protection of power supply devices from short circuits and uninterrupted power supply of automation actuators during transient electrical processes.

Known is an automatic reclosing device containing a current source, a first and second converter, a switch, a first and second comparator, a first and second reference voltage source, a trigger, an Input terminal, an Output terminal, a Common terminal (see patent No. 2272347 "Automatic reclosing device" authors Yudin VV, Peshekhonov VA Published on March 20, 2006, Bulletin No. 8).

The disadvantage of the known device is that when working with an inductive load (electric motors), with incandescent or high pressure lamps, false triggering is possible when switched on again after self-elimination of the short circuit due to high starting currents.

The closest device for the same purpose to the proposed invention in terms of the combination of features is an automatic reclosing device containing a power supply for the control circuit, a high-frequency current source, first and second converter, first and second switch, first and second voltage comparator, first and second voltage reference , D-flip-flop, logical element (LE) 2I, terminals "Input", "Output" and "Common". (see patent No. 2706332 "Device for automatic reclosing" authors V. V. Yudin, V. A. Sergeev, etc. Published on November 18, 2019, bull. No. 32) and taken as a prototype.

The reasons that impede the achievement of the technical result indicated below when using a known device taken as a prototype is a high sensitivity to an increase in current in the load supply circuit during automatic restart after self-elimination of a short circuit. In the case of operation of the device with an inductive load (for example, electric switch drives), with incandescent or high pressure lamps, repeated switching is accompanied by large inrush currents with the formation of electrical transients. Current surges will cause false tripping of the first AC-to-rectified voltage converter and unnecessary load disconnection.

The device contains D-flip-flops. Turning on the power again from the mains side without the participation of maintenance personnel will lead to the installation of a random combination of logic levels at the outputs of the D-flip-flops, which can damage the control circuit of the device, made on integrated circuits powered by a low-voltage source. The initial state of the D-flip-flops of the control circuit must be set in manual mode.

The technical result is the protection of the device from false triggering caused by large inrush currents during automatic restart after self-elimination of the short circuit in the load supply circuit and automatic setting of the initial state of the control circuit after the device is supplied with power from the power supply network.

The specified technical result is achieved by the fact that in the known automatic reclosing device containing a power source, serially connected terminal "Input", the first converter, normally closed fixed and movable contacts of the first switch, terminal "Output", the second converter connected between the fixed open contact the first switch and the "Common" terminal, the first and second voltage comparator, one input of which is connected to the information output of the first and second converter, respectively, the first and second reference voltage source, the output of which is connected to the other input of the first and second voltage comparator, respectively, logic element 2I , D-flip-flop, the output of which is connected to the control input of the first switch, and the zero setting input is connected to the output of the logic element 2I, a high-frequency current source and the second switch are connected in series on one side, the difference is that additional In addition, a pulse shaper, a circuit for setting the initial state, a pulse expander are introduced so that the output of the first comparator is connected to the input of the pulse shaper, the output of which is connected to the input of the D-flip-flop, the first input of the logic element 2I is connected to the output of the initial state setting circuit, the input of which is connected to the output of the power supply, and the input of the pulse expander is connected to the output of the second voltage comparator, and the output of the pulse expander is connected to the second input of the logic element 2I, and the second switch on the other side is connected to the open contact of the first switch and the input of the second converter, and the control inputs of the first and second switch are combined.

The essence of the invention is as follows. The automatic reclosing device for automatic reclosing has found wide application in automation executive devices, including signaling, centralization and blocking devices (STS) on the railway. During the operation of automation actuators, various kinds of influences are possible, leading to a temporary appearance of a short circuit in the power circuit, for example, a splash of wires, shorting of bundles of insulated wires, etc. The power circuit with this type of short circuit is capable of self-healing before the arrival of the repair personnel.

The automatic reclosure device consists of a power section that commutes the operating load current and converts the current into a rectified voltage, and a low-voltage section - the switch control circuit, which is powered from a separate power source. The AR device is connected to the output winding of the step-down transformer (voltage generator) using the “Input” and “Common” terminals, as well as the power source. The primary winding of the transformer is supplied with voltage from the side of the power supply network. Terminals "Output" and "Common" are connected to the load (automatic actuator) by the power supply circuit.

The load of automatic reclosing devices can be electric motors for switching points, coded path transmitters, etc. (see, for example, Soroko V.I., Fotkina Zh.V. Equipment for railway automation and telemechanics: Handbook in 4 books. Book 1. - 4th ed. - M: NPF "Planet". 2013 - 1060 p. .). When the electric motor is turned on, a transient inrush current occurs in the power supply circuit. The starting current at the beginning of the transient process exceeds the operating current by 4-8 times. Incandescent and high pressure lamps also have a significant starting current. The initial amplitude of the current and the time of the transient process depend on the nature of the load.

In the prototype, the load of the automatic reclosure device is the windings of the relay, transformers, etc. The active resistance of the relay windings significantly exceeds the active resistance of the motor windings. The voltage on the relay coils of the signaling system devices is supplied at different times, therefore the inrush currents are insignificant.

The transient process of the inrush current I _pp also occurs when connecting to the power supply network or when restoring the initial state of the automatic reclosing device after self-elimination of the short circuit (see Fig. 2a). After the transient time τ _PP , the load current decreases to the operating value I _work .

The voltage at the information output of the converter 1 "alternating current - rectified voltage" U _{p1 is} proportional to the change in current.

When a transient occurs, the starting current I _pp increases sharply. Voltage U _n1 exceeds the reference voltage U the comparator _OP1 of the first comparator 6 and the work (see. FIG. 2d). Switching the comparator will cause a false short circuit trip. To protect against false triggering, a pulse expander 15 is introduced into the proposed device. Pulse expander (see, for example, EA Zeldin, Pulse devices on microcircuits. - M .: Radio and communication, 1991 - p. 60, 61, 73) is launched pulse of the second comparator 11 τ _back with a negative voltage drop (see Fig. 2h) and allows not to interrupt the power supply to the load for the period of the transient process. The duration of the extended pulse τ _p (see Fig. 2i) is preset, its value is greater than or equal to the duration of the transient process τ _pn . The extended pulse prohibits the pulses of the shaper 8 (see, for example, Zeldin E.A. 6, switch the D-flip-flop 14 (see Fig. 2e, f).

During the operation of the automatic reclosure device, power outages are possible. After the restoration of the power supply, the constant voltage of the power supply 7 is fed to the circuit for setting the initial state 9, which forms a zero setting pulse for the D-flip-flop (see, for example, Zeldin E.A. Pulse devices on microcircuits. - M .: Radio and communication, 1991 - p. 50-57). The set logic zero at the output of the D-flip-flop provides the connection of the load through the contacts of the switch 2 with the voltage generator.

Figure 1 shows a block diagram of an automatic reclosing device.

Figure 2 shows the diagrams of the current and voltage of the device. FIG. 2a, b) solid lines show current I _Output and voltage U _Output at the “Output” terminal. The dotted lines show the full-wave rectified voltages U _p1 and U _p2 at the information outputs of the first 1 and second 10 converters, which are level compatible with the signals of the structural blocks of the device.

The device contains the first converter 1 "alternating current-rectified voltage", the first switch 2, the second switch 3, the high-frequency current source 4, the first reference voltage source 5, the first voltage comparator 6, the low-voltage power supply 7, the pulse shaper 8, the initial state setting circuit 9, the second converter 10 "alternating voltage - rectified voltage", the second voltage comparator 11, the second reference voltage source 12, logic element 13 2I, D-flip-flop 14, pulse expander 15, terminal "Input", terminal "Output", terminal " General".

The power supply network of the step-down transformer, the step-down transformer (voltage generator), the load supply circuit and the load are not shown conventionally.

The device operates as follows. In the steady-state operating mode of the device, the transient process and short circuit in the load supply circuit are absent, the operating voltage U _{pa is} applied to the device and the operating current I _slave flows (see Fig. 2a, b). At the output of the first comparator 6 there is a logic zero level. At the output of the second comparator 11, the pulse shaper 8, the circuit for setting the initial state 9, the pulse expander 15, the logic element 2I 13, there is a logical unit level (see Fig. 2 d, e, f, h, and in the time intervals t6-t7 and t13-t in Fig.2a). The logical levels of the initial state are laid down at the stage of the schematic implementation of the listed structural blocks. At the information input of the D-flip-flop 14, the level of a logical unit is constantly present. The logic level at the output of the D-flip-flop when turned on has an undefined state.

At time t1, the automatic reclosure device is connected to the power supply network (voltage generator). The power supply E _n 7 is turned on (see Fig. 2c). A constant voltage is supplied to the circuit for setting the initial state 9 of the D-flip-flop 14, which, along the leading edge of the voltage E _p, forms a pulse with a negative voltage drop U _{usn of} duration τ _set (see Fig. 2d). The pulse τ _{mouth is} fed to the first input of the logic element 2I 13 and then to the input of setting the zero of the D-flip-flop 14. At the output of the D-flip-flop at the moment of time, a logical zero is set (see voltage U _tr in Fig. 2g). A logical zero is applied to the control inputs of switches 2 and 3. The contacts of switch 2 remain in the normally closed state, and of switch 3 in the normally open state.

At the same time, a transient inrush current I occurs in the load supply circuit_nn duration τ_nn... In converter 1, the alternating load current is converted into a full-wave rectified voltage U_n1 at the information output (in Fig.2a shown with a dashed line), proportional to the load current at the output of the automatic reclosing device I_Exit... The rectified voltage is supplied to one input of the first comparator 6. The voltage U is supplied to the second input_op1 reference voltage source 5. Upon reaching the voltage U_n1 at the information output of the first reference voltage converter U_op1, the first comparator 6 is triggered and at its output the voltage U_k1 increases in a jump to the level of a logical unit (see Fig. 2e). On the leading edge of the comparator voltage U_k1 pulse shaper 8 during the transient process generates a series of pulses with a negative voltage drop of duration τ_f (see the time interval t1-t2 in Fig. 2e).

Pulse τ _f arrives at the input of the D-flip-flop, which is triggered by the trailing edge of the pulse. The pulse duration is selected from the condition τ> τ _set . At the output of the D-flip-flop, a logical unit is set, which is fed to the control inputs of switches 2 and 3 (see Fig. 2g) and switches them. After a delay time τ _{back of the} switching of the switch 2 (see the time interval t2-t3 in Fig. 2a), the second converter 10 and the high-frequency current source 4 are connected to the “Output” terminal through the closed contacts of the second switch 3. The second converter 10 converts the high-frequency alternating voltage into rectified full-wave voltage U _p2 at the information output, the amplitude of which is proportional to the change in voltage in the supply circuit U _c and load U _n (see Fig. 2b). Since there is no short circuit in the load supply circuit, the current of the high-frequency current source 4 I _it creates a voltage drop in the supply circuit U _c and in the load U _n . The sum of the voltages U _c + U _n is fed to the input of the second converter 10. From the output of the converter 10, the total voltage is fed to one input of the comparator 11, to the second input of which the reference voltage U _{op2 of the} second reference voltage source 12 is supplied. At time t4, the sum of the voltages U _c + U _n becomes more than the reference voltage U _oп2 . The second comparator 11 is triggered and at its output the level of the logical unit is changed to the level of logical zero (see Fig. 2h).

According to the negative drop in the output voltage of the second comparator 11, the pulse expander 15 forms a pulse with a negative drop in voltage of duration τ _p (see Fig. 2i). The pulse duration τ _{p is} chosen such that during the time of its action the transient process with the duration τ _pp ends. The expander pulse is fed to the second input of the logic element 2I 13, then to the input of setting the zero of the D-flip-flop 14 and holds the logic zero level at its output. The contacts of switches 2 and 3 after a delay time τ _back return to their original state at time t5 and the transient current I _pp flows through the load. The response time τ _cf required to achieve the sum of voltages U _c + U _{n of the} reference voltage U _op2 depends on the value of the current phase of the high-frequency current I _um at time t3.

During the duration of the pulse τ _p, switching of the D-flip-flop by the pulses of the shaper 8 does not occur. At the end of the transient at time t6, the operating current I _slave and the operating voltage U _{pa6 are} set in the power supply circuit. This mode remains until a short circuit appears in the load supply circuit at time t7, or until the next transient occurs when the motor is turned on, or during power outages.

If a short circuit in the load supply circuit (see. Fig. 2a pulse duration short circuit τ _kOe in the time interval t7-t11), when the electric motor during operation or when power failure device operation repeats all listed above sequence of control signals and switching load current I _Output and current I _it high-frequency current source 4. In this case, the cycle of the device at times t1-t7 is repeated in the cycle of work at times t7-t13.

Thus, the technical result - protection of the device from false triggering caused by large inrush currents during automatic restart after self-elimination of a short circuit in the load supply circuit and automatic setting of the initial state of the control circuit after being supplied to the device from the power supply network side, have been achieved.

Claims (1)

An automatic reclosing device containing a power source connected in series with the Input terminal, the first converter, normally closed fixed and movable contacts of the first switch, the Output terminal, the second converter connected between the fixed open contact of the first switch and the Common terminal, the first and a second voltage comparator, one input of which is connected to the information output of the first and second converters, respectively, the first and second reference voltage sources, the output of which is connected to the other input of the first and second voltage comparators, respectively, a logic element 2I, D-flip-flop, the output of which is connected to the control input of the first switch, and the zero setting input is connected to the output of the logic element 2I, a high-frequency current source and the second switch connected in series on one side, characterized in that a pulse shaper is additionally introduced into it, a circuit for setting the initial state pulse expander so that the output of the first comparator is connected to the input of the pulse shaper, the output of which is connected to the input of the D-flip-flop, the first input of the logic element 2I is connected to the output of the initial state setting circuit, the input of which is connected to the output of the power supply, and the input of the pulse expander connected to the output of the second voltage comparator, and the output of the pulse expander is connected to the second input of the logic element 2I, and the second switch on the other side is connected to the open contact of the first switch and the input of the second converter, and the control inputs of the first and second switch are combined.

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