Transmitter

 

The invention relates to a device for measuring liquid level in open reservoirs, canals, sewage reservoirs and other hydraulic structures. The sensor for low conductivity liquids contains a vertical magnetic circuit, sealed exciting winding, spiral bare electrode, the measuring circuit. The spiral electrode is located on top of the sealed exciting winding and in contact with the liquid. The magnetic core is made in the form of the shielding grating cylinder of the individual ferromagnetic wires, which are closed around the Central part. The Central portion includes a spiral electrode, sealed the exciting coil and the connecting conductor. The measuring circuit is connected to the lower end of the spiral electrode through an insulated conductor passing through the axis of the device. All the elements of the lower end face lattice of the cylinder of the magnetic circuit is isolated from the liquid. The technical result consists in increasing the noise immunity of the sensor. 1 C.p. f-crystals, 3 ill.

The invention relates to a device for measuring liquid level in open reservoirs, canals, sewage collectors and other hidrotehnice Erna, the river water to 0,2 - 0,3 Siemens per meter /industrial effluents/. For seawater and technical brines declared the sensor unusable.

Known transmitter containing bare spiral current electrode placed close to the potential electrode and the measuring circuit /see application UK 1603793, IPC G 01 F 23/24 from 1981/ the Disadvantages of this device are significant power consumption /tens of watts/ low noise when working near sources of interference industrial frequency of 50 Hz.

The closest in technical essence and the achieved result to the claimed technical solution is "Potentiometric sensor" that contains vertically mounted in the receptacle with conductive fluid spiral bare electrode, the lower end of which is connected in series with the Registrar and the potential electrode. The device further comprises exciting the coil /winding/ with a ferromagnetic core, which is connected to a source of alternating voltage, and the coil /coil/ is airtight and installed coaxially inside the spiral electrode /and see.with. The USSR 1627848, IPC G 01 F 23/24, bull. 6, 1991/ This allows susistence replaced by autotransformer. However, in common with similar lack of low immunity - the prototype is preserved. In fact, when the device is at the industrial frequency of 50 Hz potential electrode perceive interference from so-called "stray currents" which is inevitably present near residential and industrial objects /for example, pumping stations/. To avoid interference, it is recommended to use a different operating frequency, but this method greatly complicates the measuring circuit and still does not guarantee full protection.

The objective of the invention is to increase the noise immunity of the sensor autotransformer type.

The problem is solved by the characteristics specified in paragraph 1 of the claims, and in common with the prototype, such as the vertical magnetic core, sealed exciting winding and located over the top of her bare spiral contact with the liquid electrode and the measuring circuit, and a distinctive, essential features, such as the running of the magnetic circuit from the individual ferromagnetic wires, closing in the space around the Central part of the device and forming a shielding lattice cylindrical surface, and a measuring circuit connected to reglemente lower end face lattice of the cylinder of the magnetic circuit is isolated from the liquid.

This improves the noise immunity of the sensor.

Especially the performance of the measuring circuit of the device is reflected in paragraph 2 of the claims, namely, the measuring circuit includes a semiconductor diode is included between the lower end of the spiral electrode and one of the wires symmetrical two-wire line connected to the exciting winding of the transmitter, with control line is connected to the network 220 via a step-down transformer, and is proportional to the liquid level potential is removed from capacitor connected between one of the wires of the two-wire line and the earth.

The invention is illustrated by the following drawings.

In Fig. 1 presents a General view of the device of Fig. 2 shows a longitudinal section of the device along the line a-a of Fig. 3 given the electrical circuit of the device.

The transmitter contains the Central part 1 and the surrounding grounded lattice the front of the magnetic core 2. In turn, the Central portion 1 includes a spiral electrode 3, sealed the exciting winding 4 and connecting the insulated wire 5 passing through the axis of the device. In addition, the elements of the lower end of the grating cylinder-magnetic snazy the front of the magnetic core.

The transmitter operates as follows.

When applying to the exciting winding voltage of industrial frequency (36-50 In for security reasons, staff) of the Central part 1 acts as a step-down transformer with a number of turns at about 10 volts. The spiral electrode 3 contains approximately 100 turns of wire of rectangular cross-section (tape) made of corrosion-resistant material (e.g. stainless steel). The tape is wound with a certain "step", i.e. the gap between the coils. Accordingly, the voltage at the ends of the coiled electrode 3 is 10-12 In (peak value). More voltage is undesirable - a course in fluid significant current causes an increase in consumption of the transmitter power and leads to non-linearity of the scale of the instrument.

Because of the spiral electrode 3 is insulated from the earth, it appears a variable capacity depending on the level of the measured liquid. The maximum amplitude value of the potential is equal to half the operating voltage at the ends of the spiral electrode 3 (about 5-6). One of the half-wave potential of the spiral electrode relative to the ground through the diode VD is supplied to a symmetrical two-wire feed line, insulated from the earth.

Ministers who on the control center with a capacitor With large capacity, connected to one of the wires of the two-wire power line. Because changes in the liquid level occur relatively slowly, the time constant of the measuring circuit can reach 10 or more, which ensures suppression and periodic impulse noise.

Possible electrochemical potentials in the execution of the spiral electrode 3 made of stainless steel do not exceed the 0.05-0.1 V, which is 1-2% of the maximum value of the measured potential.

The insulating coating 6 is necessary in order to ensure strictly radial nature of the electric field EWbetween the spiral electrode 3 and lattice grounded cylinder 2. When the axial component of the field at the bottom of the gauge the scale of the instrument will become nonlinear. The same can be said about the tank bottom should have a conductivity much lower than the conductivity of the measured liquid. If the transmitter is in conditions that do not guarantee isolation tank bottom, the bottom end of the grid cylinder 2, you must put a layer insulating film, the diameter of which should exceed the maximum value of the measured level.

For operation of the electrical circuit concretelike just to collect the conductors under one sealed input to the Central part 1. In addition, the installation location of the sensor is preferably placed in a protective (e.g., concrete) camera.

The technology of assembling sensor.

Lattice the front of the magnetic core is assembled from elements of the U-shape with the finished insulation. U-shaped elements are passed through the Central part 1, and then their upper ends bent (not necessarily at right angles and welded together.

Claims

1. The sensor for low conductivity liquids, comprising a vertical magnetic circuit, sealed the exciting winding and nestled on top of her bare spiral contact with the liquid electrode and the measuring circuit, wherein the magnetic core is made in the form of the shielding grating cylinder of the individual ferromagnetic wires connected around a Central part comprising a spiral electrode, sealed the exciting coil and the connecting conductor, and a measuring circuit connected to the lower end of the spiral electrode through an insulated conductor passing through the axis of the device, all of the elements of the lower end face lattice of the cylinder of the magnetic circuit is isolated from the liquid.

2. The sensor under item 1 that distinguishes the electrode and one of the two wires of the power line, connected to the exciting winding of the transmitter, with control line is connected to the network 220 via a step-down transformer, and is proportional to the liquid level potential is removed from capacitor connected between one of the wires of the two-wire line and the ground.

 

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