RU2824649C1 - Modular device and method for protecting person from electric shock - Google Patents

Abstract

FIELD: electrical communication equipment.

SUBSTANCE: invention relates to switching devices for prevention of electric shock in case of damage of insulation of current-carrying parts of electrical installations. Invention discloses a device and method for protection against electric shock in case of damage of insulation of current-carrying parts of electrical installations (electrical equipment, electrical receivers) in rooms of civil purposes and for operation in mobile plants, characterized by frequent connections to AC network and subsequent outages, by detecting the emergency mode of the installation and controlling the contacts of the phase changer and the emergency disconnector.

EFFECT: ensuring safe operation of electrical installations due to automatic determination of the position of the phase conductor without a third point (often grounding) and automatic switching to the standard position (L—on the left, N—on the right) in case of incorrect connection.

7 cl, 5 dwg

Description

The invention relates to modular electrical devices, in particular, to switching devices for protecting a person from electric shock in the event of damage to the insulation of current-carrying parts of electrical installations (electrical equipment, electrical receivers) in civilian premises and for use in mobile installations characterized by frequent connections of electrical installations to an alternating current network and subsequent disconnections.

Field of technology

The most probable reasons for the appearance of voltage on the housings of electrical installations are:

a) reduction in insulation resistance of electrical installation elements;

b) breakage of the neutral conductor and transfer of voltage along the neutral conductor to all housings of open conductive parts of electrical installations (hereinafter referred to as OCP);

c) damage to the phase wire, its fall and transfer of phase voltage to all the power supply units;

d) in case of using protective grounding (hereinafter referred to as PEN conductor), when the contacts of the phase and neutral conductors are mixed up, when the voltage increases or decreases, when the neutral conductor breaks, when two phases enter the network, when an increased potential appears on the neutral conductor.

The danger due to: a) is eliminated by using residual current devices (hereinafter RCD) and/or differential circuit breakers (hereinafter RCBO), which contain an RCD and a circuit breaker that respond to leakage current, overload current and short-circuit current; b) and c) are usually found on overhead lines and are eliminated by using protection that responds to the voltage of the phase conductor between the RCD and the ground, or by connecting the RCD to protective grounding or to the potential equalization system (PES); d) partially by using a VKZ type device (disclosed below) only if there is grounding, the resistance of which complies with the regulatory documentation, in particular, the Electrical Installation Rules (PUE). However, the VKZ is not designed for the case when the contacts of the phase and neutral conductors are mixed up without proper grounding. However, in networks with grounding, the VKZ does not provide adequate protection, for example, in the event of breaks in the grounding conductor or an increase in grounding resistance, in particular, in the event of wear of the grounding circuit.

RCDs and RCDs record, if grounding is performed correctly, the presence of a current leak by the difference between the currents: those that left the device and those that returned. Usually, differential circuit breakers and residual-current devices operate at a current of: 10 mA, 30 mA, 100 mA, 300 mA. In this case, a person cannot independently tear himself away from the conductor (the RCD body) already at a current of 10-15 mA.

That is, none of the specified devices allows for full protection of a person from electric shock, for example, in the event of a break in the grounding conductor or incorrect connection of modular electrical devices, in particular, when the phase and neutral wires are mixed up, in the case of using the neutral conductor as a protective conductor, and also in the cases described above.

The prior art includes devices that provide protection for a person from electric shock when the phase and neutral conductors are mixed up, which is ensured by using a third point (often grounding), for example, by measuring the phase conductor-grounding, neutral conductor-grounding circuit and comparing the obtained voltage values. However, in networks with no grounding or with grounding that has high resistance, the known devices have limited application.

Thus, a residual-current device is known from the state of the art that responds to both differential current and phase-to-ground/neutral-to-ground voltage, i.e. a circuit breaker with combined protection of the VKZ (“RUZO-K”) type.

A combined residual-current device for an electric network with a grounded neutral RU 100341 U1 (H02H 3/00, 10.12.2010) comprises an automatic switch with an independent trip coil, a differential current transformer with primary conductors equal to the number of power supply wires of the electric network (2- or 4-wire) and two secondary windings, one of which is connected to the independent trip coil via a semiconductor threshold element, characterized in that an additional clamp of the protective wire and a varistor terminal are connected to the output of the contact of pole N of the switch, the other varistor terminal is connected via the second winding of the differential transformer to the input of the power supply unit and to the ground terminal, and a capacitor is connected between the outputs of the phase and neutral contacts of the switch.

The disadvantage of the RCD-K is that in the absence of reliable grounding, determining the position of the phase and neutral conductors is only possible using external means, i.e. the device itself does not have such a function.

In addition, the RCD-K has a feature of all residual-current devices - it is the ability to switch off only in the presence of leakage current. In the absence of grounding and the appearance of voltage on non-current-carrying parts of electrical installations, switching off will occur only in the event of contact with non-current-carrying parts of electrical installations. That is, as indicated above, the RCD-K will operate only when the minimum tripping current is reached, for example, 30 mA.

Also known from the prior art is a device for protection against changes in supply voltage according to patent SU 706904 A (H02H 7/10, 31.12.1979), in which the actuator is made on an electromagnetic relay, the measuring element is made on a stabilizer and two voltage dividers, while the device is equipped with two optocouplers and tunnel diodes connected in series with the optocouplers' LEDs between the terminals of the stabilizer and dividers, and the photoresistors of the optocouplers are connected in parallel with the relay. The purpose of the invention is to increase the accuracy of the device's operation by using an electrical connection between the optocouplers and tunnel diodes.

However, this device does not protect against breakage of the neutral conductor, or from confusion of the phase and neutral conductors, which can be dangerous in systems where the neutral conductor is used as the grounding conductor.

The closest technical solution to the declared one is the device for protective shutdown of consumers in a three-phase AC electrical network SU 961029 A (H02H 7/09, 23.09.1982), which protects, among other things, in the event of confusion of the neutral wire of the network with the phase wire (three-phase network), which leads to an increase in voltage that saturates the magnetic circuit of the device and a sharp increase in the consumed current by 1.73 times occurs (for example, 380 V instead of 220 V). The specified device contains a transformer-rectifier unit 1, the output of which through a current-limiting element 2, for example, a resistor, is connected between the phase and neutral wires, and the windings of the executive contactor 3 and the intermediate relay 4 are connected to the output. The control and signaling unit 5, connected via inputs 6-9 to the phase and neutral wires of the network, receives power from the output of the transformer-rectifier unit through input 10-11 and has three outputs. Output 12-13, containing closing contact 14, signals about decrease of phase voltages. Output 15-16, containing closing contact 17, signals about increase of voltage in the same way as output 18-19, containing opening contact 20. Opening contact 20 is connected in the circuit of winding of executive contactor 3. Opening contact 21 of intermediate contactor 4 is connected in the circuit of winding of executive contactor 3. Opening contacts 22-25 of executive contactor supply network voltage to consumers 26-28 and perform protective shutdown.

The disadvantage of this device is that it provides switching and protective shutdown for a network with a capacity of up to 16 kVA. Moreover, this device will not be able to track the case when the phase and neutral conductors from which the device is powered are mixed up, due to the peculiarities of alternating current (changes in the polarity of the phase conductor in a 220 V network with a frequency of 50 Hz).

The claimed device is made in a case and is a separate module for protecting a person from electric shock (hereinafter referred to as a modular device). Despite the fact that all units in the claimed device are electrically powered, the claimed modular device has the ability to convert a signal that is recognized in the device case by determining the capacitive coupling of the phase/neutral conductor and ground into a readable low-current signal from the reference unit for the control unit, which is made with the ability to compare signals received from conductors (L, N) and, based on the values obtained, set the appropriate operating mode of the device, and, if necessary, either switch the wires (phase and neutral) to the required position, or disconnect the load from the device (for example, disconnects the home network).

Capacitive electrical coupling is the interaction of two circuits using a capacitance common to both circuits. In this case, the circuits are the phase/neutral conductor and the ground, and the capacitance between them is air. Due to this, a potential difference (voltage) arises, the presence of which is recognized by the reference block. Thus, further in the text, the term capacitive coupling signal (hereinafter signal) denotes the potential difference between each of the conductors and the ground through a dielectric medium, which is air. The neutral conductor does not have a pronounced capacitive coupling with the ground, while the capacitive coupling for the phase conductor will always be higher than on the neutral conductor.

The technical result of the claimed invention consists in ensuring the safe operation of electrical installations, due to the automatic determination of the position of the phase conductor without a third point (often grounding) and their automatic switching to the standard position (L - left, N - right) in the event of their incorrect connection.

The claimed technical result is achieved by implementing a modular device and method for protecting a person from electric shock. Moreover, the modular device for protecting a person from electric shock contains a power supply unit, a control unit, a phase shifter and an emergency disconnector. The power supply unit and the phase shifter are designed with the ability to receive voltage from the network, and the power supply unit is connected to the control unit, the support unit, the phase shifter and the emergency disconnector for their power supply. For automatic determination of the phase conductor position, the modular device comprises a reference unit configured to convert signals from the network conductors, received alternately from the phase shifter, by using capacitive coupling of the conductors and the ground, into a readable signal for the control unit, for which purpose it includes: a transistor and a resistor optocoupler and at least three resistors, wherein the transistor is connected to the phase shifter via the first resistor and is connected to the second resistor, wherein the first and second resistors are connected to each other, and the transistor is connected to the optocoupler, the photoresistor of which forms a voltage divider with the third resistor, and a control unit configured to determine the resistance values from signals received from the voltage divider of the reference unit and to control the contacts of the phase shifter and the emergency disconnector to continue operation in the required mode based on the resistance comparison data.

Moreover, the control unit controls the contacts of the phase shifter and the emergency disconnector of the modular device: in normal operating mode by closing the contacts of the emergency disconnector relay, in pre-emergency operating mode by switching the contacts of the phase shifter to the opposite ones and by closing the contacts of the emergency disconnector relay, and in the case of emergency operating mode by not controlling the contacts of the phase shifter and the emergency disconnector.

A bipolar transistor or field-effect transistor is used as transistor 3.3 of the supporting block 3.

In this case, a galvanic isolation unit may be implemented in the device, including a resistor optocoupler, at least two resistors, and powered through a support unit. Each of the phase shifter and the emergency disconnector may include at least one switching relay with two groups of contacts or may include at least two switching relays.

The modular device can also additionally include a display 6 or LEDs for indication, and a self-diagnostic and voltage control unit 7.

Moreover, the method of protecting a person from electric shock includes the following sequence of actions: alternately receiving signals from each of the network conductors by the reference unit of the modular device through the phase shifter, converting the signal from each of the conductors by the reference unit into a readable signal for the control unit, due to the use of capacitive coupling of the conductors and the ground, determining the position of the phase conductor by the control unit due to comparing the resistance values from each of the signals received from the phase and neutral conductors of the network, received from the reference unit, and setting the operating modes of the modular device by the control unit by controlling the contacts of the phase shifter and the emergency disconnector based on the comparison data, the obtained resistance values. The following operating modes of the modular device are set: normal operating mode, pre-emergency operating mode and emergency mode.

The phase shifter and emergency disconnector of the modular device are controlled in normal operation by closing the contacts of the emergency disconnector relay, in pre-emergency operation by switching the phase shifter contacts to the opposite ones and closing the contacts of the emergency disconnector relay, and in the event of emergency operation by not controlling the contacts of the phase shifter and emergency disconnector.

The following drawings are provided to illustrate the implementation of the invention.

Fig. 1 shows the basic version of the functional diagram for the implementation of a modular device;

Fig. 2 shows the functional diagram of the support block;

Fig. 3 shows an example of using the claimed device;

Fig. 4 shows the switching diagram of the device in accordance with the operating modes;

Fig. 5 shows a variant of the functional diagram of the implementation of a modular device with additional blocks.

In the main embodiment of the invention, the modular device contains (Fig. 1): power supply unit 1, control unit 2, support unit 3, phase shifter 4, emergency disconnector 5. The connections between the units of the device are made by standard means for devices of this type.

Power supply unit 1 is directly connected to control unit 2, support unit 3, phase shifter 4, emergency disconnector 5.

As a power supply unit 1, a step-down AC-DC converter can be used to convert AC 230V voltage into a stabilized DC 5V voltage with a maximum output current of up to 3 amperes.

A microcontroller can preferably be used as control unit 2. Transistor assembly units, processors, comparators, etc. can also be used for control and monitoring.

The support block 3 (Fig. 2) performs the function of converting signals from the network conductors into a readable low-current signal for the control block 2 and includes: at least three resistors (3.1, 3.2, 3.4), a transistor 3.3, and a resistor optocoupler 3.5.

As the transistor 3.3, a bipolar transistor may preferably be used, and a field-effect transistor may also be used.

Transistor 3.3 is designed to control the voltage supplied to the resistor optocoupler 3.5, for which purpose transistor 3.3 is connected to power supply unit 1, to phase shifter 4 via first resistor 3.1 and to optocoupler 3.5. The first resistor 3.1 performs the function of current limiting. Also connected to transistor 3.3 is the second resistor 3.2, connected to the first resistor 3.1 to reduce the sensitivity of transistor 3.3 to input signals from phase shifter 4. In this case, the third resistor 3.4 is connected to optocoupler 3.5, forming a voltage divider (not shown) with the internal photoresistor of optocoupler 3.5. For stable operation of optocoupler 3.5, a fourth resistor 3.6 can be added.

Also, diodes, capacitors and additional resistors can be used in the support block 3 as strapping to increase the accuracy of signal recognition.

Moreover, it is possible to implement a resistor optocoupler 3.5 and at least one resistor 3.4 as a separate galvanic isolation unit. In this case, the galvanic isolation unit is powered through the support unit 3.

Each of the phase shifter 4 and the emergency disconnector 5 includes at least one switching relay with two groups of contacts (Fig. 3, not marked), or it is possible to use two switching relays in each of the said devices. Also, the phase shifter 4 and the emergency disconnector 5 can be combined in one relay or it is possible to use other types of switching devices, for example, triacs, solid-state relays, etc.

Additionally (Fig. 5), the modular device may include a display 6, a self-diagnostic unit 7 and a voltage control unit.

The device works as follows.

Fig. 4 shows an example of using a modular device in a civil network. The modular device is installed after the input circuit breaker before the group circuit breakers or RCDs, RCDs, etc. and is connected to the network with its upper terminals and to the load with its lower terminals.

The following units of the declared device are directly connected to the electrical network (to phase (L), zero (N), if mixed up, then vice versa): power supply unit 1, phase shifter 4 (Fig. 1, 4).

When the device is connected to the network, voltage is supplied to power supply unit 1 and phase shifter 4, then through phase shifter 4 to emergency disconnector 5.

Power is supplied from power supply unit 1 to control unit 2, support unit 3, phase shifter 4 and emergency disconnector 5.

Initialization of control unit 2 is performed. Control unit 2 begins to read the signal from the left terminal of the device (usually L - left) through the reference unit 3 from the phase shifter 4, remembers the signal value, then sends a signal to switch the phase shifter 4 and also reads the signal from the right terminal (usually N - right), due to switching the phase shifter 4, and compares the received signal values, then sets the operating mode of the modular device (Fig. 1-3).

The reference block 3 (Fig. 2) receives signals in turn from the phase (L), then from zero (N) of the network (if mixed up, then vice versa) from the phase shifter 4 through the first resistor 3.1, while the second resistor 3.2 reduces the sensitivity of the transistor 3.3, and accordingly the signals from the transistor (3.3) are fed in turn to the resistor optocoupler 3.5, where, depending on the level of the signal coming from the reference block 3, glow occurs in the resistor optocoupler 3.5.

Since the signals from phase (L) and zero (N) arrive at reference block 3 alternately, the potential difference (voltage) arises due to the above-described capacitive coupling of each of the conductors and the ground, which is recognized by transistor 3.3.

The degree of opening of transistor 3.3 is always higher for the phase conductor than for the neutral conductor. Thus, the voltage supplied to optocoupler 3.5 from transistor 3.3 will always be higher from the phase conductor than from the neutral conductor, and accordingly the glow in optocoupler 3.5 will be different for the conductors.

Resistor optocoupler 3.5 (Fig. 2) receives signals from reference block 3. The value of the glow intensity of the diode (not shown) of resistor optocoupler 3.5 is recorded by an internal photoresistor (not shown) of optocoupler 3.5. The resistance of the photoresistor changes depending on the glow intensity of the diode; the brighter the glow of the diode, the lower the resistance of the photoresistor.

Control unit 2 reads the resistance values from the photoresistor of the resistor optocoupler 3.5, using the voltage divider (see above), calculates the resistance values from each of the conductors and compares the obtained resistance values.

Based on the resistance comparison data, control unit 2 determines which of the conductors is the phase conductor and sets the further operating mode of the modular device (the conductor with the lower resistance value is the phase conductor).

Control unit 2 sets the following modes (Fig. 4) for controlling the device:

(1) normal operating mode,

(2) pre-emergency operating mode,

(3) emergency mode.

After initialization of the device, the position of the phase conductor is determined (usually L - on the left, N - on the right).

The phase conductor position is determined by means of capacitive coupling of the phase and neutral conductors and the ground, this coupling is alternately recognized by the reference unit 3, then the signals are alternately galvanically isolated by means of the resistor optocoupler 3.5 and they are read by the control unit 2, by measuring the resistance from the photoresistor, which is part of the resistor optocoupler 3.5, by means of the voltage divider (see above). Thus, the resistance of the photoresistor of the resistor optocoupler 3.5, when a signal is applied to it from the transistor 3.3, which is read from the phase conductor, will always be lower than the signal read from the neutral conductor.

The contacts are controlled based on the comparison data of signals from the phase and neutral conductors, i.e. the conductor with the lower resistance is the phase conductor. For the correct operation of control unit 2, the obtained values, as quantities, do not have a determining value.

Based on the specified resistance comparison data, control unit 2 sets the operating mode of the modular device by controlling the contacts of phase shifter 4 and emergency disconnector 5.

(1) In case of normal operation (1:0, phase left) the control signal:

- to switch ON emergency disconnector 5 (contacts 5.2 with 5.3 and contacts 5.5 with 5.6 on the emergency disconnector relay 5 are closed, Fig. 3). Phase shifter 4 is in a static position (the control signal is not supplied, contacts 4.2 with 4.1 and 4.5 with 4.4 are closed, Fig. 3),

- to DISPLAY on display 6 information (optional, Fig. 5) about the operation of the device in normal mode (if the device does not use a display, then LEDs for indication).

(2) In case of pre-emergency mode operation (0:1, phase right) control signal:

- to SWITCH the contacts of phase shifter 4 to the opposite ones (contacts 4.2 with 4.3 and contacts 4.5 with 4.6 on phase shifter relay 4 are closed, Fig. 3), and

- to turn ON the emergency disconnector 5 (contacts 5.2 with 5.3 and contacts 5.5 with 5.6 on the emergency disconnector relay 5 are closed, Fig. 3), while

- DISPLAY on display 6 information (optional, Fig. 5) about the operation of the device in pre-emergency mode.

(3) In case of emergency operation (zero break, two phases, high and low voltage, etc.), control unit 2 does not send a control signal to phase shifter 4 and emergency disconnector 5, i.e. the modular device does not supply power to the load.

Fig. 5 shows an approximate diagram of the claimed device with additional units such as self-diagnosis and voltage control unit 7. Voltage control is implemented by parallel connection of unit 7 to the electric network. Voltage measurement occurs by reducing the network voltage to the voltage read by control unit 2. Self-diagnosis is implemented by measuring the voltage from the upper left terminal and from the lower right terminal, thus, if the device has set the wrong operating mode, the measured voltage will be equal to 0 V, this will be tracked by control unit 2 and will start the re-initialization process, in case of correct connection, the voltage will be equal to the network voltage. In this case, self-diagnosis and voltage control unit 7 contains: at least three resistors, at least four diodes, at least one electrolytic capacitor. Unit 7 can also contain at least one transformer. In the first case, due to the voltage divider, the voltage is reduced, then the voltage is rectified by diodes and smoothed by a capacitor, thus converting the network voltage into a linear voltage read by control unit 2. In the second case, the voltage is reduced and galvanically isolated by a transformer, then the voltage is rectified by diodes, reduced by a divider formed by resistors, smoothed by a capacitor and shunted by a resistor to increase sensitivity to voltage pulses, thus converting the network voltage into a linear voltage read for control unit 2.

Thus, due to the modular device and method for protecting a person from electric shock, safe operation of installations is ensured, which allows preventing electric shock to a person in case of damage to the insulation of current-carrying parts of electrical installations (electrical equipment, electrical receivers) or other situations in which current leakage occurs to non-current-carrying parts of electrical installations, due to determining the position of the phase and neutral conductors without a third point (often grounding) and automatic switching of their position in case of determining the phase conductor in place of the neutral conductor, as well as in additional implementation options allows protection against overvoltage, low voltage, breakage of the neutral conductor and the appearance of a dangerous potential on the neutral conductor.

Claims (18)

1. A modular device for ensuring the safe operation of electrical installations, comprising: a power supply unit, a control unit, a phase shifter and an emergency disconnector, characterized in that contains a support block, designed with the possibility of converting signals from network conductors for the control unit, for which it includes: a transistor and a resistor optocoupler and at least three resistors, wherein the transistor is connected to the power supply, to the phase shifter through the first resistor and to the optocoupler and is connected to the second resistor, with the first and second resistors connected to each other, and the photoresistor of the optocoupler forms a voltage divider with the third resistor, the power supply unit and the phase shifter are designed with the ability to receive voltage from the network, and the power supply unit is connected to the control unit, the support unit, the phase shifter and the emergency disconnector for their power supply, and each of: the phase shifter and the emergency disconnector include at least one changeover relay with two sets of contacts, and the control unit is designed with the ability to alternately read signals from the network conductors from the phase shifter through the photoresistor of the resistor optocoupler of the support block, due to the voltage divider, in the form of resistance values, and with the ability to calculate the resistance values from each of the conductors and compare the obtained resistance values, and determine, based on the data from comparing the resistance values, which of the conductors is the phase conductor, and establish the further operating mode of the modular device by controlling the contacts of the phase shifter and the emergency disconnector to continue operation in the required mode based on the resistance comparison data: in normal operating mode by closing the contacts of the emergency disconnector relay, with the contacts of the phase shifter closed, in pre-emergency operating mode by switching the contacts of the phase shifter to the opposite ones and by closing the contacts of the emergency disconnector relay, and in the event of an emergency mode, the control unit does not send a control signal to the phase shifter and the emergency disconnector. 2. A modular device according to item 1, in which a bipolar transistor or a field-effect transistor is used as the transistor of the support block. 3. A modular device according to item 1, in which a galvanic isolation unit can be implemented, including a resistor optocoupler, at least two resistors, and powered through a support unit. 4. The modular device according to claim 1, wherein each of the phase shifter and the emergency disconnector includes at least two switching relays. 5. The modular device according to item 1, additionally including a display or LEDs for indication. 6. A modular device according to item 1, additionally including a self-diagnostic and voltage control unit. 7. A method for ensuring the safe operation of electrical installations, including the following sequence of actions: - initialization of the control unit of a modular device to ensure safe operation of electrical installations, containing a power supply unit, a control unit, a phase shifter, an emergency disconnector, a support unit and connected to the electrical network directly through the power supply unit and the phase shifter, wherein the support block of the modular device contains a transistor and a resistor optocoupler and at least three resistors, wherein the transistor is connected to the power supply, to the phase shifter through the first resistor and to the optocoupler and is connected to the second resistor, wherein the first and second resistors are connected to each other, and the photoresistor of the optocoupler forms a voltage divider with the third resistor, - alternate reading of signals from the network conductors by the control unit from the phase shifter through the photoresistor of the resistor optocoupler of the reference block, due to the voltage divider, in the form of resistance values, and - calculation of resistance values from each of the conductors by the control unit, comparison of the obtained resistance values and determination of which of the conductors is the phase conductor, based on the comparison of resistance values, - establishment of a further operating mode of the modular device by the control unit by controlling the contacts of the phase shifter and the emergency disconnector to continue operation in the required mode based on the resistance comparison data: in normal operating mode by closing the contacts of the emergency disconnector relay, with the phase shifter contacts closed, in pre-emergency operating mode by switching the phase shifter contacts to the opposite ones and by closing the contacts of the emergency disconnector relay, and in the event of an emergency mode the control unit does not send a control signal to the phase shifter and the emergency disconnector.