Method for measuring the induced current and the energy released in the resistance bridge of an electric initiator and a device for implementing it

Abstract

FIELD: electrical measuring technology.SUBSTANCE: invention relates to the measurement of induced current and released energy in the resistance bridge of an electrical initiation device (EID) included in objects during their testing for operational safety under conditions of exposure to electromagnetic fields (EID) of various origins. The method for measuring the induced current and the released energy is to determine the shift of the Bragg resonance coming from the sensor. The shift is recorded by tracking the spectral shift not of the fundamental resonance of the Bragg grating, but of the secondary harmonic, which has a smaller spectral width and, therefore, a smaller noise amplitude. The device for measuring induced current and released energy includes specialized software, a multi-channel optical interrogator, an electric field strength meter, a passive optical N-channel splitter, and a new induced current and released energy sensor, which is a Bragg grating formed in the core of a single-mode optical fibre with a diameter of 50 mcm, 1 mm long, and with a disrupted periodicity of its structure (its uneven application). A metal film is applied to the surface of the section of optical fibre with a Bragg grating, which acts as an equivalent of the EID resistance bridge.EFFECT: increase in accuracy, as well as a decrease in the sensitivity threshold for measuring the values of induced current (released energies) flowing (released) in the EID resistance bridge, when testing objects for explosion safety under conditions of exposure to electromagnetic fields of various origins.2 cl, 2 dwg

Description

[0001] Technical field

[0002] The invention relates to the field of electrical measuring technology, namely, to the measurement of induced current and released energy in the glow bridge of an electrical initiation means (EIM) included in objects during their testing for operational safety under conditions of exposure to electromagnetic fields (EMF) of various origins.

[0003] In accordance with the requirements and terminology of OTT 1.2.10-2001, objects containing ESI must undergo explosion safety tests when exposed to electromagnetic fields of various origins. During testing, it is necessary to measure the values ​​of induced currents and released energies in the electrical circuits intended for activating the ESI. The current (energy) sensor is located in the housing of the ESI, and the current (energy) flowing through the ESI's heating bridge is measured. The ESI's heating bridge may be replaced with an equivalent one with a resistance identical to the standard one. The vast majority of ESI manufactured in Russia have a heating bridge resistance of 1 to 7 ohms. The housing of the ESI with the induced current and released energy sensor housed within is called a special assembly.

[0004] State of the art

[0005] A device for monitoring the electrical parameters of pyrotechnic devices is known (see Russian patent No. 2602994, priority dated September 21, 2015), containing an analog-to-digital converter, a voltage meter, a resistance calculator, a demultiplexer, a test current generator, a current limiter, and a control result generation unit.

[0006] The disadvantage of this technical solution is the strong influence of the measuring system on the measurement results, caused by the presence of a galvanic connection between the ESI filament bridge and the induced current sensor, as well as the influence of the measuring lines on the structure of the electromagnetic field affecting the test object.

[0007] A system for measuring induced currents in a resistive element of an electric explosive device (EED) is known (see patent RU 2664763 C1, published 08 / 22 / 2018).

[0008] This system comprises an induced current signal generator, a duplex fiber-optic communication line, and an interface converter for communication with a computer. The signal generator comprises a scale amplifier with a controlled gain, an induced current primary transducer, an absolute signal value extraction module, a peak detector and an analog-to-digital converter, an optical transmitter, and an optical receiver with a control digital signal decoder. The interface converter comprises a control signal generator, an optical digital receiver, a microprocessor for signal pre-processing, and a high-speed USB interface generator.

[0009] The resistive element of the EED under test is connected to the scale amplifier input, which is also connected to the standard power supply circuit of the device. A temperature sensor, which is thermally coupled to the resistive element of the EED, can also be connected to the scale amplifier input. The scale amplifier is designed as a microwave signal detector with a logarithmic dependence of the output signal on the induced high-frequency current on the resistive element of the EED.

[0010] The disadvantages of this technical solution are:

[0011] - the influence of the measuring system on the measurement results, caused by the presence of a galvanic connection between the filament bridge of the ESI and the scale amplifier of the measuring system;

[0012] - the presence of electronics of the measuring system (scale amplifier, communication lines and optical transmitter) inside and outside the ESI, which leads to a change in the structure of the acting electromagnetic field when testing small-sized objects (the dimensions of the object are comparable to the dimensions of the measuring system).

[0013] A method for testing systems containing electric explosive devices for resistance to the effects of external electromagnetic fields in the composition of objects and a device for implementing it are known (see patent RU 2 593 521 C1, published 10.08.2016).

[0014] According to this method, a multi-channel test system for assessing the resistance of electric explosive devices to electromagnetic interference contains a test interference generator, an EMF emitting antenna, a receiving antenna located in the area of ​​the test object and connected to a field strength meter, a conversion device, a measuring communication line with the test object, a control device, placed on a test site.The mobile test bench is equipped with an optical multi-channel interrogator, an interface, a meter for the level of emitted test EMF, a device for automatic control of the system's operating modes, synchronization of the operation of all its elements, processing of experimental data and documentation of test results with the provision of precise time synchronization of all elements of the system with a radiating antenna for the formation of an external test EMF with specified spatial and polarization parameters of radiation, a power amplifier for the test EMF signal with a software-controlled generator of standard test signals, a multi-channel device for converting signals of equivalent EMF, a passive multi-channel splitter.

[0015] In this system, the equivalent of the EVU can be implemented with a fiber-optic connector for inputting the optical signal of the interrogator and receiving the optical signal reflected by the Bragg grating, a feed-through optical connector of a three-channel sensitive element - a fiber-optic current-to-temperature converter of the EVU equivalent, with an arrangement inside the EVU housing of sensitive elements on fiber-optic current-to-temperature converters made of optical fiber with built-in Bragg gratings, structurally combined with the equivalents of the igniter filaments and installed on the printed circuit board of the device for converting signals of the equivalents of electric igniters of the EVU, connected to the electrical connector of the source for initiating the operation of the EVU, installed in one end of the EVU, the second end of which is made with a threaded connection for installing the equivalent of the EVU in place of the standard EVU of the tested object.

[0016] In a dual-filament EVU, three sensitive elements on Bragg gratings, each several millimeters in size, can be used, which are formed in a single optical fiber, spaced several centimeters apart along the fiber, and combined with electrodynamic equivalents of the igniter filaments into a single structure.

[0017] The equivalent of the filament can be made in the form of a frameless spiral wire resistor, the diameter and length of which are matched to the diameter and linear size of the fiber Bragg grating, while the active resistance of the equivalent is selected equal to the resistance of the filament (from 0.6 to 12.0 Ohm), and a reduction in its inductive resistance is ensured by bifilar winding of the spiral.

[0018] The disadvantages of this technical solution are:

[0019] - complexity of manufacturing a special assembly;

[0020] -high sensitivity threshold of induced current sensors of the measuring system.

[0021] The closest in technical solution and chosen by the authors as a prototype is a device for measuring the induced current in the glow bridge of an electric initiation means (see patent RU 2831340 C1, published 04.12.2024).

[0022] This device consists of a multichannel optical interrogator, an electric field strength meter, a passive optical N-channel splitter, and an induced current sensor. The induced current sensor is a Bragg grating formed in the core of a 50-μm-diameter single-mode optical fiber with a metal film deposited on top. This film acts as an equivalent of the ESI filament bridge with a resistance identical to that of a standard filament bridge.

[0023] The disadvantage of this technical solution is the high sensitivity threshold.

[0024] The technical result, which the proposed invention is aimed at achieving, is an increase in the accuracy, as well as a decrease in the sensitivity threshold of measuring the values ​​of induced current (released energies) flowing (released) in the incandescent bridge of the ESI, when testing objects for explosion safety under conditions of exposure to electromagnetic fields of various origins.

[0025] Disclosure of the essence of the invention

[0026] The invention consists of a device for measuring induced current and released energy, including specialized software, a multichannel optical interrogator, an electric field strength meter, and a passive optical N-channel splitter. It also utilizes a new induced current and released energy sensor, which is a 1 mm long Bragg grating formed in the core of a single-mode optical fiber with a diameter of 50 μm and a non-uniform deposition of its structure. A metal film is deposited on the surface of the optical fiber in the area containing the Bragg grating, acting as an equivalent of the filament bridge of the ESI. The metal film of the sensor is manufactured such that its resistance is identical to the resistance of the filament bridge of a standard ESI.The Bragg resonances of the induced current (released energy) sensors are selected within the wavelength range of the interrogator (1460 to 1620 nm). The current and energy sensors are connected to the interrogator via optical splitters. The total length of fiber-optic connections from the interrogator to each sensor should not exceed 50 meters.

[0027] The proposed method utilizes cold, standard ESIs, which incorporate an induced current (released energy) sensor based on a Bragg grating. The sensor's metal film is connected to the ESI's filament bridge contacts. The metal film, which serves as the filament bridge, is made of silver. The film thickness is selected based on the resistance of the standard ESI's filament bridge. When current flows through the metal film, heat is generated, which is transferred to the Bragg grating, leading to a shift in its Bragg resonance. This shift in Bragg resonance is proportional to the current flowing through the metal film. Using a 1 mm-long Bragg grating with a distorted periodicity in its structure leads to the appearance of secondary harmonics of the Bragg resonance. Secondary harmonics have a smaller spectral width than the fundamental resonance, which in turn allows for increased accuracy in determining the Bragg resonance shift.The conversion of the Bragg resonance shift into induced current (released energy) is performed by specialized software. The space inside the special assembly is filled with thermal insulation material to minimize environmental influences on the measurement results.

[0028] Dedicated software captures and tracks all controlled points (extrema) of the Bragg resonance (all peaks and troughs). The final value of the Bragg resonance shift is determined by the controlled point with the lowest noise amplitude.

[0029] This technical solution allows to increase the accuracy of measuring induced current and released energy due to:

[0030] - reducing the length of the Bragg grating, since the heat generated by the conductive film is concentrated in a smaller volume;

[0031] - determination of the shift of the Bragg resonance by the secondary harmonic with the smallest width and amplitude of noise;

[0032] - using thermal insulation material to fill the internal volumes of a special assembly to minimize environmental influences (reducing interference during measurements);

[0033] - using a software algorithm that tracks the shift of not only the main Bragg resonance, but also all its secondary harmonics.

[0034] The amplitude of the induced current and released energy flowing in the sensor's metal film is determined by recalculating the Bragg resonance shift using a calibration curve. This recalculation is performed automatically by specialized software. Improved measurement accuracy and a lower sensor sensitivity threshold are also achieved by minimizing environmental influences and synchronizing the start time of measurement and the onset of EMF exposure through continuous monitoring of the applied field parameters using an electric field strength meter.

[0035] What is new in the proposed invention is: an induced current sensor, a special assembly design, and an algorithm for processing information coming from the induced current sensor and the released energy.

[0036] The combination of essential features in the proposed invention has made it possible to increase the accuracy and also to lower the sensitivity threshold of measuring the induced current and the released energy in the equivalent of an incandescent bridge (ESI) when testing objects for explosion safety when exposed to EMF of various origins due to the design of the induced current and released energy sensor and the software algorithm for processing information.

[0037] The technical result is also ensured by the use of dielectric materials (optical fiber) that do not affect the structure of the EMF affecting the object.

[0038] Brief description of drawings

[0039] The essence of the invention and its implementation are explained in Fig. 1-2, where

[0040] Fig. 1 shows a schematic diagram of a device for measuring the induced current and the released energy in the ESI filament bridge;

[0041] Fig.2 shows a schematic representation of the new induced current and released energy sensor.

[0042] Designations in Fig. 1:

[0043] 1 - special software;

[0044] 2 - Multi-channel optical interrogator;

[0045] 3 - interrogator channel;

[0046] 4 - Passive optical N-channel splitter;

[0047] 5 - electric field strength meter;

[0048] 6 - ​​induced current and released energy sensor;

[0049] 7 - Electric initiation device;

[0050] 8 - test object;

[0051] 9 - connecting optical fiber. Designations in Fig. 2:

[0052] 10 - a section of optical fiber with a 1 mm long unevenly applied Bragg grating and a metal film (silver layer);

[0053] 11 - connecting wire.

[0054] Implementation of the invention

[0055] The developed device for measuring the induced current and the released energy in the ESI incandescent bridge during explosion safety testing of objects exposed to electromagnetic fields of various origins includes: an automated workstation with special software for recording and processing the results (1), an optical 4-channel interrogator MICRON OPTICS si155 (2), a passive N-channel optical splitter (4), an optical connecting fiber (9), a Bragg sensor of induced current and released energy with a violation of the periodicity of the structure of its lattice and a deposited metal film, connected instead of the standard ESI incandescent bridge (6), an electric field strength meter (5).

[0056] As a result of the study of the created device sample, the following metrological characteristics were obtained:

[0057] - resistance of the sensor heating bridge: 1-6 Ohm;

[0058] - sensor sensitivity threshold when measuring induced current: no more than 0.7 mA;

[0059] - upper limit of the sensor measurement range when measuring induced current: not less than 60 mA;

[0060] - measurement error of the induced current value in the range from 0.7 to 1.2 mA: no more than 20%;

[0061] - measurement error of the induced current value in the range from 1.2 to 60 mA: no more than 4.5%;

[0062] - the sensitivity threshold of the sensor when measuring the released energy: no more than 1 μJ;

[0063] - upper limit of the measurement range of released energy: not less than 1000 μJ;

[0064] - the measurement error of the released energy value in the range from 1 to 20 μJ: no more than 20%;

[0065] - the measurement error of the induced current value in the range from 20 to 1000 μJ: no more than 4.5%;

[0066] - the rate of increase of the signal amplitude from 0.1 to 0.9 from the maximum level for a current of 1 mA: no more than 400 ms;

[0067] - dimensions of the current and energy sensor: 8x3x3 mm.

[0068] Industrial applicability

[0069] The proposed method for measuring the induced current and the released energy in the incandescent bridge of an ESI can be used by research and development organizations, design bureaus and any other organizations involved in testing objects containing ESI for explosion safety when exposed to EMF of various origins.

Claims

1. A method for measuring the induced current and the released energy in the glow bridge of an electrical initiation means (EIM) included in objects during their testing for exposure to electromagnetic fields (EMF) of various origins, which consists of creating test electromagnetic fields external to the test object, with specified radiation parameters that are recorded by an electric field strength meter installed near the test object, assessing the values ​​of the induced currents and released energies in the test object, characterized in that the assessment of the values ​​of the induced currents and released energies in the test object is carried out on the basis of measurement information obtained by tracking the spectral shift not of the fundamental resonance of the Bragg grating, but of the secondary harmonic, which has a smaller spectral width, and consequently, a smaller noise amplitude.

2. A device for measuring the induced current and the released energy in the heating bridge of an electrical initiating means (EIM) included in objects during their testing for exposure to electromagnetic fields (EMF) of various origins, consisting of a multi-channel optical interrogator, an electric field strength meter, a passive optical N-channel splitter and a sensor of induced current and released energy, characterized in that the sensor of induced current and released energy is a Bragg grating of 1 mm in length formed in the core of a single-mode optical fiber with a diameter of 50 μm with its uneven application, a metal film is applied to the surface of the section of the optical fiber with the Bragg grating, which acts as an equivalent of the heating bridge of the EIM, the metal film of the sensor is manufactured in such a way that its resistance is identical to the resistance of the heating bridge of the standard EIM,Bragg resonances of the current sensors are selected in the wavelength range at which the interrogator operates from 1460 to 1620 nm, the current and energy sensors are connected to the interrogator via optical splitters, the total length of fiber-optic connections from the interrogator to each sensor should not exceed 50 m, induced current sensors are installed in the housings of de-energized standard ESI, which are filled with heat-insulating material to minimize the influence of the environment on the measurement results.

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