RU2826132C1 - Remote load control device - Google Patents

Abstract

FIELD: electronic equipment.

SUBSTANCE: invention relates to electronic engineering and can be used in automated process control systems (APCS). Remote load control device consists of a controller, first, second and third control relays, first, second and third current sensors, first, second and third current-limiting resistors. Remote control device has the following capabilities: in the “Load control” mode, it connects or disconnects the load from the power supply in response to commands from external devices; in “Control” mode automatically tests connecting lines for breakage and short circuit; controls its own performance; informs external devices on occurrence of such emergency situations as break or short circuit of load, break or short circuit of connecting lines, as well as on own failure.

EFFECT: providing continuous monitoring of both its own operability and integrity of connecting lines connecting the remote control device to the power source and the load.

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Description

The proposed invention relates to the field of electronic engineering and can be used in automated process control systems (APCS).

According to the standards and rules for designing fire protection systems [1], the control device for fire extinguishing installations as an element of the general automated process control system must ensure automatic monitoring of the connecting lines of the remote start for breaks and short circuits. The reliability of the entire system is increased if the following are additionally monitored:

- the integrity of the connecting lines between the power source and the load, which is the input circuit of the fire extinguishing system, which is usually the coil of an electromagnetic relay, starter or valve;

- the operability of remote starting elements, which are usually the contacts of the load control relay;

- readiness of the remote control device to switch from the control mode to the operating load control mode at any time.

The closest technical solution to the proposed invention is a remote control device [2], consisting of a controller, a voltage sensor connected in parallel to the contacts of the control relay, which are closed or opened by a signal coming from the controller. The signal about the integrity of the connecting lines between the remote control device and the load is formed by the controller based on the results of comparing the voltage at the ends of the normally open contact of the control relay, coming from the voltage sensor, with the voltage value stored in the controller's memory.

The aim of the invention is to create a device for remote control of a load with continuous monitoring of both its own operability and the integrity of the connecting lines connecting it to the power source and the load.

The stated goal is achieved by the fact that the remote load control device (hereinafter referred to as the device), consisting of a controller connected by the first group communication line to other devices of the automated process control system, the first control relay, additionally includes a second and third control relay, the first, second and third current sensors, and the first, second and third current-limiting resistors.

Fig. 1 shows a block diagram of the claimed device 1, the controller K of which is connected by the first group communication line 2 to other devices of the automated process control system, from which it can receive power, signals establishing the normal operating mode of the device 1 (the "Load Control" mode / the "Control" mode) and commands controlling the load H ("Turn on the load" / "Turn off the load"), the "Reset" command, and also inform other devices of the automated process control system about the occurrence of an emergency situation (about an open or short circuit of the load H, about open or short circuits of the first 3, second 4, third 5 and fourth 6 connecting lines, as well as about a malfunction of the device 1 itself).

The controller K of the claimed device 1, upon command from other devices of the automated process control system or according to the program embedded in it:

- via the first 7 communication line, the first P1 control relay sends a signal to “On” or “Off”, between the first 8 and second 9 terminals of contact 10 of which the first R1 current-limiting resistor and the first DT1 current sensor are connected in series;

- via the second 11 communication line, the second P2 control relay sends a signal to “On” or “Off”, between the first 12 and second 13 terminals of contact 14 of which the second R2 current-limiting resistor and the second DT2 current sensor are connected in series;

- via the third 15 communication line, the third R3 control relay sends a signal "On" or "Off", the first terminal 16 of contact 17 of which is connected to the second 9 terminal of contact 10 of the first P1 control relay, and its second terminal 18 is connected to the first terminal 19 of the third DT3 current sensor, the second terminal 20 of which is connected to the first terminal 12 of contact 14 of the second P2 control relay. Between the first 16 and second 18 terminals of contact 17 of the third P3 control relay, the third R3 current-limiting resistor is connected.

Outputs 21, 22 and 23 of the first DT1, second DT2 and third DT3 current sensors are connected to the controller K by the second group communication line 24.

Load H is connected by the first 3 and second 4 connecting lines, respectively, to the second terminal 9 of contact 10 of the first P1 control relay and to the first 12 terminal of contact 14 of the second P2 control relay; power source IP is connected by the third 5 and fourth 6 connecting lines, respectively, to the first 8 terminal of contact 10 of the first P1 control relay and to the second 13 terminal of contact 14 of the second P2 control relay.

The first R1, the second R2, the third R3 current-limiting resistors, having a resistance much greater than the resistance of the load H, are selected in such a way that in any operating mode of device 1 the current flowing through them, on the one hand, is less than the current for holding the load H in the on state, and on the other hand, is sufficient for actuating the corresponding series-connected first DT1, second DT2 and third DT3 current sensors, which, when actuated, generate signals at their corresponding outputs 21, 22 and 23, perceived by controller K as logical "1", and in the non-actuated state - as logical "0". Optocouplers providing galvanic isolation between the high-voltage and low-voltage circuits of device 1 and connected according to one of the circuits described in [3] can be used as the first DT1, second DT2 and third DT3 current sensors.

Let's consider the operation of the claimed device 1.

In the "Load control" mode, contact 17 of the third control relay RZ must be constantly in the open state. In this case, the load resistance H shunts the series-connected third R3 current-limiting resistor and the third DT3 current sensor, at the output 23 of which a logical "O" signal is formed. Upon the "Turn on the load" command received from other devices of the APCS via the first line of communication group 2, the controller K via the first 7 and second 11 communication lines sends "Turn on" signals to the first P1 and second P2 control relays to close the corresponding contacts 10 and 14, thereby connecting the load H to the voltage of the power source IP and shunting, respectively, the first R1 and second R2 current-limiting resistors, the first DT1 and second DT2 current sensors, at the outputs 21 and 22 of which logical "0" signals are formed. Upon the command “Turn off the load” received from other devices of the automated process control system via the first group communication line 2, the controller K via the first 7 and/or second 11 communication lines sends signals to the first P1 and/or second P2 control relay to open the contacts 10 and/or 14 corresponding to them, thereby disconnecting the load H from the voltage of the power source IP and removing the shunting of the first R1 and/or second R2 current-limiting resistors, the first DT1 and/or second DT2 current sensors, at the outputs 21 and/or 22 of which logical “1” signals are generated.

In the "Control" mode, the controller K automatically sends certain combinations of "On" and/or "Off" signals via the first 7, second 11 and third 15 communication lines to the first P1, second P2 and third P3 control relays for closing and/or opening the contacts 10, 14 and 17 corresponding to them, without connecting the load H to the power source voltage IP. Fig. 2 shows Table 1, which summarizes all permissible combinations of such signals and the corresponding logical levels at the outputs 21, 22 and 23 of the first DT1, second DT2 and third DT3 current sensors, respectively, which are sent to the controller K via the second group communication line 24 for comparison with the corresponding control logical levels stored in its memory. Based on the results of such comparison, the controller K sends a signal via the first group communication line 2 to other devices of the APCS about the presence or absence of an emergency situation. For correct operation of device 1 in the “Control” mode, the internal resistance of the third DT3 current sensor must be much less than the load resistance H, so that when contact 17 of the third P3 control relay is closed, shunting the third R3 current-limiting resistor, a logical “1” signal is formed at output 23 of the third DT3 current sensor.

A mismatch between the logical levels at outputs 21, 22 and 23 of the first DT1, second DT2 and third DTZ current sensors and the control logical levels stored in the memory of the K controller will indicate the occurrence of an emergency situation, which may be caused, for example, by the following reasons:

- break of the first 3 and/or second 4 connecting lines;

- break in the third 5 and/or fourth 6 connecting lines;

- short circuit in load H;

- emergency short circuit of the first 3 with the second 4 or with the third 5, or with the fourth 6 connecting lines;

- emergency short circuit of the second 4 with the third 5 or fourth 6 connecting lines;

- malfunction of the first P1 and/or second P2 and/or third RZ control relay, contacts 10, 14 and 17 of which are constantly in a closed or open state, regardless of the signals received from the controller K via the first 7, second 11 and third 15 communication lines.

When any emergency situation occurs, it is advisable for the controller K, regardless of the operating mode of device 1, to stop switching contacts 10, 14 and 17 of the first P1, second P2 and third P3 control relays until the fault is completely eliminated. Table 2 in Fig. 3 shows examples of combinations of "On" / "Off" signals for some of the emergency situations described above, coming from the controller K via the first 7, second 11 and third 15 communication lines to the first P1, second P2 and third P3 control relays, respectively, and the corresponding logical levels at the outputs 21, 22 and 23 of the first DT1, second DT2 and third DT3 current sensors. Particularly dangerous are emergency situations similar, for example, to an emergency short circuit of connecting lines 4 and 5, which can disable the second P2 control relay. In order to maintain the operability of the first P1, second P2 and third P3 control relays in device 1, it is necessary to provide for their protection against overload and short circuit, implemented, for example, using the technical solutions described in [4]. When such protection is triggered, contacts 10, 14 and 17 of the first P1, second P2 and third P3 control relays must go into the open state regardless of the signals coming from the controller K. Return to the normal operating mode can occur after the emergency situation is eliminated automatically or by the “Reset” command received from other devices of the APCS.

In order to use the claimed device 1 most effectively, the first P1 and/or the second P2 control relay can be made either with normally closed or with normally open contacts 10 and/or 14. Thus, for example, when organizing a remote control circuit for a self-holding starter [5], it is advisable to make the first P1 control relay with a normally open contact 10, connecting it in parallel with the "Start" button, and the second P2 control relay - with a normally closed contact 14, connecting it in a circuit in series with the "Stop" button (Fig. 4). Then, in the "Load control" mode, turning on the first P1 control relay on the "Turn on the load" command will be equivalent to pressing the "Start" button, and turning off the second P2 control relay on the "Turn off the load" command will be equivalent to pressing the "Stop" button.

Sources of information

1. SP 5.13130.2009. Code of Practice. Automatic Fire Alarm and Fire Extinguishing Systems: approved and put into effect by order of the Ministry of Emergency Situations of Russia dated 25.03.2009 No. 175: introduced on 01.05.2009 - Moscow: FGU VNIIPO EMERCOM of Russia, 2009. - 172 p.

2. Patent No. 2525043 Russian Federation, IPC F16K 31/12. Method for continuous monitoring of the integrity of pipeline valve control circuits and a circuit for its implementation.

3. AC network detector. - Text: electronic // Electrical circuits ELWO.RU: site. - URL: https://elwo.iri/publ/skhem

Claims (1)

A remote load control device consisting of a controller connected via a first group communication line to other devices of an automated process control system (APCS), a first control relay characterized in that a second and a third control relay, a first, second and third current sensors, a first, second and third current-limiting resistors are additionally introduced into it; the controller is connected: via the first communication line to the first control relay, between the first and second contact terminals of which the first current-limiting resistor and the first current sensor are connected in series; via the second communication line to the second control relay, between the first and second contact terminals of which the second current-limiting resistor and the second current sensor are connected in series; via the third communication line to the third control relay, the first contact terminal of which is connected to the second contact terminal of the first control relay, and its second terminal is connected to the first terminal of the third current sensor, the second terminal of which is connected to the first contact terminal of the second control relay; a third current-limiting resistor is connected between the first and second contact terminals of the third control relay; the outputs of the first, second and third current sensors are connected via the second group communication line to the controller; the load is connected by the first and second connecting lines respectively to the second terminal of the contact of the first control relay and to the first terminal of the contact of the second control relay; the power source is connected by the third and fourth connecting lines respectively to the first terminal of the contact of the first control relay and to the second terminal of the contact of the second control relay.

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