BG2064U1 - Optical sensor for measuring of strong currents - Google Patents

Abstract

An optical sensor for measuring strong currents is used in industry and in particular for measuring the current in the power distribution devices (substation), the control of technological processes in the extraction of non-ferrous metals by electrolysis, using induction furnaces. The optical sensor is also applicable in all cases where it is necessary to measure the electric current with a size of tens or hundreds kilo ampere. The sensor used as a source of optical radiation laser, emitting a signal and at the same time abutment wave sufficiently separated so as not to overlap, and polarisers which polarize only the shorter wavelength emitted by the laser.

Description

Field of technology

The utility model refers to an optical sensor for measuring high currents, which is used in industry and especially for measuring current in powerful power distribution devices (substations), for control of technological processes in the extraction of non-ferrous metals by electrolysis and the use of induction furnaces. .

BACKGROUND OF THE INVENTION

The strength of the electric current is one of the most frequently measured quantities in technology. Classic sensors, such as shunt resistors, current transformers and magnetic amplifiers, are used for its measurement. Each of these groups of sensors has its advantages, but also disadvantages such as large volume, high cost, measuring only constant or only variable current values. With the new generation of sensors, current and voltage are measured non-contact.

Optical sensors for measuring the strength of electric current are known, which use the magneto-optical Faraday effect. In these sensors, light propagates through a medium with a relatively large Verde constant. In the case of the sensor in question, this medium is a crystal. The Faraday effect is expressed in the rotation of the plane of polarization of polarized radiation, when it passes through a crystal under the influence of a magnetic field applied longitudinally to the crystal. To obtain polarized radiation and to analyze the effect of rotation on the plane of polarization, the crystal is placed between two crossed polarizers. As it propagates, light passes through a first polarizer, then through a crystal, and then through a second polarizer, crossed by the first and called an analyzer. Rotating the plane of polarization increases the intensity of the light wave passing through the analyzer. This intensity is proportional to the magnetic field. It is measured and used to judge the magnitude of the magnetic field. In turn, the magnetic field is proportional to the electric current that creates it. Thus, an unambiguous connection is obtained between the measured intensity of the light wave passing through the sensitive element and the strength of the electric current.

Optical sensors for measuring the strength of electric current are known, which include sources of signal and reference wave, fiber-optic coupler, optical 10 fiber for supplying optical radiation, sensitive element (including a crystal with two crossed polarizers), receivers of the optical radiation, amplifiers and measuring electronic unit.

A disadvantage of the known optical sensors for determining the strength of the electric current is the use of two separate optical sources, respectively of a signal and a reference wave and a coupler, which makes the construction more expensive and complicated.

Technical essence of the utility model

The task of the utility model is to create an optical sensor for measuring high currents with a 25 simplified optical scheme of introducing radiation into the sensitive element, with high sensitivity and providing measurement with increased accuracy at low cost.

This problem is solved by the optical sensor 30 for measuring strong currents, which according to the utility model includes a sequentially arranged source of coherent light, misleading the optical fiber, a sensitive element composed of dichroic 35 crossed polarizers located in front of and behind the crystal. made of bismuth sylenite (Bil2SiO20), optical fiber output, electronic signal processing unit and measuring unit with 40 display. The coherent light source is a laser source of optical radiation emitting both a signal wave at 530 nm and a reference wave at 808 nm. The dichroic polarizers of the sensing element have a 45 operating range of polarization of light in the range of 450-760 nm.

The signal processing unit of the optical sensor for determining strong currents includes a dichroic mirror for spatial separation of the signal and reference waves,

2064 W photodiodes converting the intensity of optical radiation into an electrical signal and electronic amplifiers of the electrical signal.

The measured value - the strength of the electric current shown on the display of the electronic unit is the ratio between the intensity of the signal wave polarized under the influence of the strength of the electric current and the intensity of the non-polarized reference wave.

The optical sensor, according to the utility model, is applicable in all cases where it is necessary to measure an electric current with a size of tens or hundreds of kiloamperes.

An advantage of the optical sensor, according to the utility model, is its ability to measure high currents with great accuracy, using a simplified optical circuit, its high sensitivity and low cost.

Explanation of the attached figure

Figure 1 shows a block diagram of the optical sensor for determining high currents.

Examples of implementation of the utility model

The optical sensor is illustrated by the following embodiment.

Example 1

The sensitive element 3 of the optical sensor shown in FIG. 1 shall be placed perpendicular to the conductor through which the current to be measured flows.

The laser source 1 is switched on, which starts to emit both a signal wave at 530 nm and a reference wave at 808 nm. The signal and reference light waves are fed through the optical fiber 2 to the sensing element 3. The light waves pass through the dichroic polarizer 4 of the sensing element 3. The dichroic polarizer 4 polarizes only the signal wave. Thus the polarized signal wave and the non-polarized reference wave pass through the crystal 5 of the sensitive element 3, in which under the influence of the measured electric current a magnetic field is generated in the conductor, which changes the intensity of the signal wave passing through it and does not change the intensity of the reference wave. . The intensity-varying signal wave and the remaining intensity-unchanged reference wave pass through the dichroic polarizer 6, which has the same 10 polarization range but is crossed with the dichroic polarizer 4. The signal and reference light waves are then delivered through the optical fiber 7 to the fiber for signal processing 8, where the signal wave and the 15 reference wave are spatially separated, their intensity is converted into an electrical signal, which is amplified and fed to the electronic unit 9. The electronic unit 9 measures the ratio of the electrical 20 signals corresponding to the signal and reference wave and visualizes directly the measured strength of the electric current in units of measurement on the SI system on the display.

Claims (1)

Optical sensor for measuring high currents, comprising an optical radiation source, an optical fiber, a sensing element, an optical radiation receiver, an amplifier and a 3θ measuring unit, characterized in that the optical radiation source (1) is a laser emitting simultaneously a signal wave of 530 nm and a reference wave of 808 nm, which is connected by a misleading optical fiber (2) to the sensitive 3 5 element (3), consisting of dichroic crossed polarizers (4 and 6) with an operating range of polarization of light from 450 to 760 nm, located in front of and behind a crystal of bismuth sylenite (5), connected by a leading 49 optical fiber (7) with a signal processing unit (8) and a measuring unit with a display (9).