A DEVICE FOR MONITORING THE PARAMETERS OF A SINGLE-PHASE AC ELECTRIC NETWORK

Abstract

The utility model relates to the field of electrical engineering, in particular to portable devices for monitoring the parameters of a single-phase alternating current electrical network, and can be used to check the correctness of the connection of socket contacts, the operability of residual current devices (RCDs), and to measure the voltage and electrical frequency of the network. It comprises a housing with a plug, a connection correctness indicator unit, a test differential current generation unit for testing the residual current device, a voltage measuring unit, an information display unit, and an alternating voltage frequency meter, including a means for reading a signal from the network, a means for electrical isolation and voltage limitation, a means for generating a measuring signal, and a computing module. The functionality of the device is expanded due to increased accuracy in monitoring the state of a single-phase alternating current electrical network. 11 clauses, 4 figs.

Description

[0001] The utility model relates to the field of electrical engineering, in particular to portable devices for monitoring the parameters of a single-phase alternating current electrical network, and can be used to check the correct connection of socket contacts, the operability of residual current devices (RCDs), and to measure the voltage and electrical frequency of the network [G01R 31 / 04].

[0002] Robiton ST-02 socket tester is known [https: / / www.chipdip.ru / product / st-02-tester-rozetok-robiton-9000928706?utm_source=direct&utm_medium=cpc&utm_campaign=Y_brand_robiton&utm_content=Tovary&utm_term=---autotargeting&etext=2202.nEvdNSsrNCchkxConEqZaek5exOBRvFCTlHBixAVCL9lemVuY2JsdWZieGhyZ21o.8a3e026830ec9b9c780a65cf183fd0629cde57a0&yclid=7723045456879812607&ybaip=1], designed to check the correct connection of contacts of electrical sockets with a Euro connector, as well as the operation RCDs of the circuit breakers to which the tested sockets are connected. The tester's LED indicator indicates whether the contacts are connected correctly. The device identifies reversed and unconnected wires and verifies that the residual-current device (RCD) operates properly (protection against fault currents of 30 mA).

[0003] A known electrical outlet tester [CN201278011 (Y), published on 2009-07-22], a part of the circuit of which contains a ground terminal, a resistor R1, a diode D1, an LED LD1, a zero line terminal, a diode D2, an LED LD2, a resistor R2, a live line terminal, an LED LD3, a diode D3 and a resistor R3, which are connected in series to form a circuit in which the diode D1, the LED LD1, the diode D2 and the LED LD2 in the circuit have a cathode-anode direction, and the connection direction of the emitting LED LD2, which is the cathode-anode direction. The diode LD3 and the diode D3 in the circuit are connected in the anode-cathode direction. This utility model primarily solves the technical problem associated with the fact that checking the status of a socket with an electroscope or multimeter requires more in-depth knowledge of electrical engineering and does not allow the average user to quickly and conveniently determine the status of the socket and intuitively assess possible faults.

[0004] The closest analogue is a tester for checking removable electrical sockets [GB 2366675A, published 13.03.2002], in particular three-pin sockets, consisting of a housing with a rear panel on which conductive pins are located, intended for connection to the corresponding contacts of the socket. On the front panel of the housing there are multiple light-emitting devices, such as LEDs, to indicate the serviceability and / or faulty wiring of the socket. The light-emitting devices are arranged in the shape of a triangle, practically repeating the shape of the conductors of the socket. LEDs can be provided that are capable of illuminating two (red and green) or three (red, green and yellow) colors, as well as blinking.

[0005] The disadvantage of known prototypes and analogues is the lack of the ability to measure the frequency of alternating voltage of the network, which limits its diagnostic capabilities when checking the quality of power supply, generators and uninterruptible power supplies.

[0006] The purpose of a utility model is to eliminate the shortcomings of analogues and the prototype.

[0007] The technical result of the utility model consists in expanding the functional capabilities of the device by increasing the accuracy of monitoring the state of a single-phase AC electrical network.

[0008] The specified technical result is achieved in that the device for monitoring the parameters of a single-phase alternating current electrical network, comprising a housing with a plug for connection to a socket, a unit for indicating the correctness of the connection of conductors, a unit for generating a test differential current for checking a residual-current device, a voltage measuring unit and information display means, characterized in that it contains a frequency meter for alternating voltage of the network, including a means for picking up a signal from the network, a means for electrical isolation and limiting voltage, a means for generating a measuring signal and a computing module configured with the possibility of processing the specified signal and outputting the frequency value to the display means.

[0009] In particular, the means for generating the measuring signal is designed in the form of a detector of the transition of the network voltage through zero.

[0010] In particular, the means for generating the measuring signal is based on a bidirectional optocoupler.

[0011] In particular, the means for generating the measuring signal is based on a digital comparator with hysteresis.

[0012] In particular, the frequency meter is designed using an analog-to-digital converter, and the computing module is designed to determine the frequency from digital samples of the signal waveform.

[0013] In particular, the computing module is designed with the ability to determine the frequency based on the moments of change of sign of the digital signal.

[0014] In particular, the computing module is configured to determine the frequency by spectral analysis of digital signal samples.

[0015] In particular, the computing module is designed with the ability to average measurements over several consecutive periods.

[0016] In particular, the computing module is configured to automatically determine the network type based on the range of the measured frequency and indicate the 50 Hz, 60 Hz or less than 50 Hz mode.

[0017] In particular, automatic detection of the network type is carried out by comparing the measured frequency with pre-set acceptable value ranges.

[0018] In particular, the computing module is configured to determine the instability of the network frequency by analyzing the deviation of the measured frequency values ​​over time.

[0019] In particular, instability is determined by the magnitude of the standard deviation of frequency over a given time interval.

[0020] In particular, instability is determined by the maximum swing of frequency deviations over a given time interval.

[0021] In particular, when the instability threshold is exceeded, the device generates a visual or audible warning signal.

[0022] Specifically, the frequency meter and display device are connected via parallel or serial interface.

[0023] Brief description of drawings.

[0024] Fig. 1 shows a device for monitoring the parameters of a single-phase alternating current electrical network, front view.

[0025] Fig. 2 shows a device for monitoring the parameters of a single-phase AC electrical network, rear view.

[0026] Fig. 3 shows a device for monitoring the parameters of a single-phase AC electrical network, rear view.

[0027] Fig. 4 shows a device for monitoring the parameters of a single-phase alternating current electrical network with the plug removed, rear view.

[0028] The figures indicate: 1 - housing; 2 - plug; 3 - contacts (phase L and neutral N); 4 - grounding contact clamp (PE); 5 - indication unit; 6 - generation unit; 7 - voltage measurement unit; 8 - frequency meter; 9 - information display unit; 10 - signal pickup unit; 11 - electrical isolation and voltage limiting unit; 12 - measuring signal generation unit; 13 - computing module.

[0029] Implementation of a utility model

[0030] This device is designed for operational monitoring of single-phase AC power parameters (e.g., 220-230 V, 50 Hz or less than 50 Hz, 60 Hz) directly when plugged into a power outlet. The device combines the following functions:

[0031] checking the correct connection of conductors (L, N, PE);

[0032] Formation of test differential current to check residual current device (RCD);

[0033] measurement of effective voltage value;

[0034] network frequency measurement;

[0035] frequency stability analysis;

[0036] automatic detection of network type (50 / 60Hz or less than 50Hz);

[0037] Display results and generate warning alarm.

[0038] The device for monitoring the parameters of a single-phase alternating current electrical network comprises a housing 1 with a plug 2 for providing connection to a network socket (see Fig. 1).

[0039] In one embodiment, the plug is made for a 220 V connector (a standard socket for household appliances in an apartment), on which phase (L) and neutral (N) contacts 3 are mounted, made in the form of round rods, and a grounding (PE) contact clamp 4, made in the form of a plate (see Fig. 2).

[0040] In another embodiment, the plug is made for the “RSH-VSH 220 V” connector for an electric stove, on which the phase (L) and neutral (N) contacts 3 and the grounding (PE) contact clamp 4 are mounted, made in the form of flat rods (see Fig. 3).

[0041] In the housing 1, a unit for indicating the correctness of the conductor connection 5, a unit for generating a test differential current 6, a voltage measurement unit 7 and a frequency meter 8 are mounted (see Fig. 4).

[0042] The indicator unit 5 for the correct connection of conductors is based on a potential comparison circuit between L - N, L - PE, N - PE using limiting resistors and LED indicators or microcontroller inputs.

[0043] The 6 test differential current generating unit contains a resistive circuit between L and PE (or L and N via PE), switched by a button or an electronic key, providing a leakage current of a given value (for example, 10-30 mA) for testing the RCD.

[0044] The voltage measuring unit 7 is based on a voltage divider and / or an isolated measuring converter with subsequent signal rectification or digitalization.

[0045] On the housing 1, an information display means 9 is mounted, which, in various embodiments, can be implemented in the form of a liquid crystal display (LCD), an LED indicator, or a combined indication of both.

[0046] The frequency meter 8 contains a means for picking up a signal 10 from the network, a means for electrically isolating and limiting the voltage 11, a means for generating 12 a measuring signal and a computing module 13, made on the basis of a microcontroller, with the ability to process said signal and output the frequency value to the information display means 9.

[0047] When the threshold values ​​of instability of the AC electrical network parameters (voltage, frequency) are exceeded, the device generates a visual and / or audible warning signal sent to the information display unit 9.

[0048] In various embodiments of the device, the frequency meter 8 and the information display means 9 are connected via a parallel or serial interface.

[0049] The device for monitoring the parameters of a single-phase AC electrical network is used as follows.

[0050] After the device is plugged into the controlled socket, the device will automatically:

[0051] analyzes the connection diagram of phase, neutral and ground wires;

[0052] measures voltage;

[0053] measures frequency;

[0054] defines the network type;

[0055] evaluates the frequency stability;

[0056] Displays values ​​on the display;

[0057] Generates a warning if necessary.

[0058] When the button is pressed forcibly, the device creates a test leakage current to check the RCD and displays on the display whether it is connected and working correctly.

[0059] In the embodiment of the measuring signal generation means 12 in the form of a network voltage zero-crossing detector, a scaled network signal is read from the signal acquisition means 10, for example, a high-impedance resistive divider. Pulses are generated at the moments of voltage zero-crossings via the electrical isolation and voltage limiting means 11 (for example, an optocoupler or RC circuit), and the microcontroller timer records the periods. The period T is calculated as the difference in the times of two identical transitions, and the frequency f is calculated using the expression:

[0060] f = 1 / T,

[0061] where f is the network frequency; T is the period.

[0062] To improve the accuracy of readings, it is possible to use the average value over N periods.

[0063] In the embodiment of the means for generating 12 a measuring signal based on a bidirectional optocoupler, for example, an optocoupler with a bidirectional LED (of the type with two oppositely connected LEDs), pulses are generated at the output with a frequency equal to double the network frequency or equal to the network frequency - depending on the connection circuit.

[0064] In the embodiment of the means for generating 12 a measuring signal based on a digital comparator with hysteresis, a resistive divider and a Schmitt comparator are used, which makes it possible to eliminate front jitter in the presence of noise, and the computing module 13 has the ability to determine the frequency based on digital readings of the signal shape.

[0065] In the embodiment of the computing module 13 using an analog-to-digital converter (ADC), the network signal is fed through the signal pickup means 10 to the ADC input of the microcontroller and the frequency is determined based on the moments of measuring the value (sign) of the digital signal, by means of spectral analysis of the digital signal samples, including for determining the dominant harmonic, averaging measurements over several consecutive periods, as well as with the ability to automatically determine the network type based on the range of the measured frequency and indication of the 50 Hz, 60 Hz mode.

[0066] The operating algorithm of computing module 13 is as follows:

[0067] 1. Initialization;

[0068] 2. Checking the correctness of the connection;

[0069] 3. Voltage measurement;

[0070] 4. Frequency measurement (zero crossing registration, period calculation, averaging over N periods);

[0071] 5. Network type detection:

[0072] - if the frequency f corresponds to the values ​​of 49-51 Hz, then the mode is 50 Hz;

[0073] - if the frequency f corresponds to the values ​​59-61 Hz, then the mode is 60 Hz.

[0074] 6. Instability analysis:

[0075] - calculation of standard deviation;

[0076] - Calculate the maximum swing.

[0077] 7. When the threshold is exceeded, a warning signal is generated.

[0078] 8. Data display.

[0079] In the claimed device, the computing module 13 is additionally configured with the ability to correctly determine the frequency f of the alternating voltage in the range of up to 50 Hz, for example 45-49 Hz, as well as significantly below the nominal value (down to 10-45 Hz), which may occur: in emergency modes of the power system; when powered by autonomous diesel generators; when operating from frequency converters; during laboratory tests.

[0080] In this case, the device operates according to the signal period, namely, as the frequency f decreases, the signal period increases:

[0081] - at 50 Hz→T=20 ms,

[0082] - at 45 Hz→T≈22.22 ms,

[0083] - at 10 Hz→T=100 ms,

[0084] The computing module 13 operates as follows: the measuring signal generator 12 generates pulses at each voltage zero crossing. The microcontroller's timer is started on the first edge. The timer is stopped on the next edge of the same name. The period is calculated using the expression:

[0085] T = t2 - t1,

[0086] where t1 and t2 are the time of switching on and off the timer on the first and second edges of the same name,

[0087] and the frequency f is determined by the expression:

[0088] f = 1 / T.

[0089] In the embodiment of the computing module 13 using an analog-to-digital converter (ADC), at frequency values ​​of up to 50 Hz, the following is used: continuous sampling of the signal, determination of the moments of change of sign of digital readings, interpolation of the moment of transition through zero, averaging over several periods T.

[0090] In the automatic low frequency recognition algorithm, the computing module 13 performs:

[0091] 1. Primary frequency measurement.

[0092] 2. If f<49Hz → the "low frequency" mode is activated.

[0093] 3. The averaging window is increased.

[0094] 4. Instability analysis is in progress.

[0095] 5. When f < the set alarm threshold (e.g. 47 Hz or 45 Hz):

[0096] - a warning signal is generated;

[0097] - the message “Low frequency” is displayed.

[0098] When the device operates in a range of less than 50 Hz, the following are additionally analyzed:

[0099] - standard deviation of frequency;

[0100] - maximum swing;

[0101] - rate of change of frequency (df / dt).

[0102] In this case, the device algorithm is as follows:

[0103] 1. The zero detector generates pulses.

[0104] 2. 1MHz timer records intervals.

[0105] 3. 16 periods are measured.

[0106] 4. If the total time is 355 ms:

[0107] f = 16 / 0.355≈45.07 Hz.

[0108] 5. Calculate σ (standard deviation).

[0109] 6. When the permissible value is exceeded, an alarm signal is generated.

[0110] The use of the 8-frequency meter in the declared device not only expands the functionality of the device, but also increases the information content of network status monitoring and the ability to diagnose power supply instability.

[0111] The implementation of the means for generating the 12 measuring signal in the form of a detector of the transition of the network voltage through zero ensures not only the reliability of the frequency measurement method and minimal computational load, but also high noise immunity.

[0112] The implementation of the means for generating the 12 measuring signal based on a bidirectional optocoupler, for example, an optocoupler with a bidirectional LED (the type with two oppositely connected LEDs), ensures not only galvanic isolation of the signal, but also increases electrical safety during operation of the device.

[0113] The implementation of the means for generating the 12 measuring signal based on a digital comparator with hysteresis improves the accuracy of determining the moment of crossing zero in noise.

[0114] The implementation of computing module 13 using an analog-to-digital converter (ADC) not only expands the functionality of the device, but also allows for the analysis of the signal shape and harmonics.

[0115] The implementation of computing module 13 using the method of determining frequency through spectral analysis of digital signal samples makes it possible to correctly measure the frequency with a distorted voltage waveform.

[0116] The implementation of the computing module 13 using the method of averaging measurements over several consecutive periods reduces the influence of random fluctuations and improves the accuracy of the frequency determination process.

[0117] The implementation of computing module 13 with the ability to determine the instability of the network frequency by analyzing the deviation of the measured frequency values ​​over time makes it possible to identify violations of the quality indicators (voltage, frequency) of electric power.

[0118] The implementation of the frequency measurement mode below 50 Hz in the declared device ensures: an expansion of the range of measured frequencies, the ability to diagnose emergency modes of the power system, control of autonomous power sources, increased measurement accuracy over long periods and increased reliability of the assessment of the quality of electric power.

[0119] Thus, the declared device as a utility model provides for the expansion of the device’s functionality, increased frequency measurement accuracy, increased safety, the ability to diagnose power quality and universal application in networks of less than 50, 50 and 60 Hz.

Claims

1. A device for monitoring the parameters of a single-phase alternating current electrical network, comprising a housing with a plug for connection to a socket, a unit for indicating the correct connection of conductors, a unit for generating a test differential current for checking a residual-current device, a voltage measuring unit and information display means, characterized in that it contains a frequency meter for alternating voltage of the network, including a means for picking up a signal from the network, a means for electrically isolating and limiting the voltage, a means for generating a measuring signal and a computing module configured to process said signal and output the frequency value to the display means, the computing module is configured to average measurements over several successive periods, with the ability to automatically determine the type of network based on the range of the measured frequency and indicate the mode of 50 Hz, 60 Hz or less than 50 Hz,and also with the ability to determine the instability of the network frequency by analyzing the deviation of the measured frequency values ​​over time.

2. The device according to paragraph 1, characterized in that the means for generating the measuring signal is made in the form of a detector of the transition of the network voltage through zero.

3. The device according to item 1, characterized in that the means for generating the measuring signal is made on the basis of a bidirectional optocoupler.

4. The device according to item 1, characterized in that the means for generating the measuring signal is made on the basis of a digital comparator with hysteresis.

5. The device according to claim 1, characterized in that the frequency meter is made using an analog-to-digital converter, and the computing module is made with the ability to determine the frequency based on digital readings of the signal form.

6. The device according to paragraph 5, characterized in that the computing module is designed with the ability to determine the frequency based on the moments of change of sign of the digital signal.

7. The device according to claim 5, characterized in that the computing module is configured to determine the frequency by means of spectral analysis of digital signal samples.

8. The device according to claim 1, characterized in that the automatic determination of the network type is carried out by comparing the measured frequency with pre-set ranges of acceptable values.

9. The device according to paragraph 1, characterized in that the instability is determined by the value of the standard deviation of the frequency over a given time interval.

10. The device according to claim 1, characterized in that the instability is determined by the maximum range of frequency deviations over a given time interval.

11. The device according to claim 1, characterized in that when the instability threshold value is exceeded, the device generates a visual or audible warning signal.

12. The device according to claim 1, characterized in that the frequency meter and the display means are connected via a parallel or serial interface.

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