SU516907A2 - Level switch - Google Patents

Description

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The invention relates to the field of controlling the level of volatile materials and liquids and can be used in the mining, petroleum, chemical and other industries.

According to the main auth. No. 489958, a signaling device for monitoring the limit level of bulk materials and liquids is known, which contains a level sensor with an electrode and a guard ring, an electronic relay with a response delay and an output electromagnetic relay. However, the effect of electrode leakage on the sensitivity of the device when performing level sensor circuits with intrinsically safe parameters will be confounded.

The purpose of the invention is to reduce the effect of inter-electrode leakage on the sensitivity of a device when performing level sensor circuits with intrinsically safe parameters. This is achieved by introducing a parametric stabilizer and resistive, 1st divider, installed at the input of the comparator, the outputs of the parametric stabilizer are connected to one of the splitter points, one output is postdated, and the second output of increased voltage is through a resistor, and the middle point resistive de.pntel connected to the guard ring.

A schematic diagram of the detector is shown in the drawing.

The level indicator contains a mains transformer 1, a bridge rectifier 2, parametric stabilizers 3 and 4, a guard ring 5 of the sensor level, an electrode b of the vessel of the technological vessel 7, a diode-regenerative comparator 8 with inputs 9 and 10, resistors 11 and 12, an amplifier with a delay pa triggering 13, the equivalent resistance of the electrode gap 14 and 15 and resistors 16 and 17 ..

The detector works as follows.

When the level sensor electrode 6 is in contact with a high-resistance KfbiM material but a circuit, there is a minus clamp of the parametric stabilizer 4, the vessel of the technological vessel 7, controls; 1 material, electrode 6, input 9 of the cokaparator 8, resistors 16 and 17, positive terminal parameter of the stabilizer pa 3 - current passes. As a result of the predominance of the potential at the input 9 of the comparator 8, the latter generates pulses, which triggers the amplifier 13. During operation of the device, electrical conductive dust, moisture, etc., are deposited on the sensor insulator (case of the process vessel 7 guard ring 5 and guard ring 5 - electrode 6). In this case, the circuit-case of the process vessel 7, the leakage resistance 14, the resistor 12, the positive terminal, the parameter 1 of the stabilizer 3 - the leakage current flows. The lower the leakage resistance, the greater the voltage drop across resistor 12, and, moreover, the more negative

1b

a voltage is applied to the input 9, thereby compensating for a decrease in potential at the floor, input, caused by the shunting effect of leakage resistance 15 between electrode 6 and the guard ring 5. This stabilizes the sensitivity of the device when the leakage resistance varies in the range from Oo to 10 com

When controlling the level of materials with high electrical conductivity, a parametric stabilizer consisting of two series-connected stabilizers 3 and

4, goes out of the stabilization mode, since the current KOpOTKOiro for gykan agra) is primary from the intrinsic resistance condition and the limiting resistance of stabilizer 4 is much greater than the limiting resistance. NIN stabilizer 3.

At the same time, stabilizer 3, having a lower output voltage and a higher spark, and current are dangerous. from the stabilization mode does not go. In this way. the power source does not affect the at h | -stance; the comparator.

Formula and 3 about b and e and

Liquid ti level indicator ti on auth. St. No. 48995S, about tl to those who read telg, what about; with "the tree is clever;, -. influence of interelectrode leakage on the device's sensitivity when executing the level sensor circuits with safety parameters, in negatively, the parametric stabilization; a resistive divider set at the inlet com -.-. parator, and the parametric outputs

stabilizer connection; one of the output points is directly connected, and the second output of the increased papr henn is through a resistor, and the middle point of the E-splitter is connected to the circuit breaker.