SU1232825A1 - Method of ensuring spark-proof operation - Google Patents

Description

one

The invention relates to coal chemical, oil and gas, and other industrial sectors where electrical equipment is operated in potentially explosive atmospheres, and is intended to ensure safe transmission of electrical energy from the power source to the load.

The purpose of the invention is to increase the reliability of intrinsically safe systems.

The method of providing intrinsic safety consists in the simultaneous extraction of signals, which is proportional to the rate of change of voltage at the output of the power supply and load current. Each of these signals is digitized, for example, logical 1 with increasing and logical O with decreasing, and the trip-controlling signal is formed by logical addition of the received modulo two signals.

The drawing shows a device for implementing the proposed method

The device contains a 1-source with a sensor 2 signal proportional to the rate of change of voltage, which is digitized by converter 3 and sensor 4 of an signal proportional to the rate of change of load current, which is converted to digital form by converter 5, a logical element EXCLUDED OR 6, amplifier 7 , high-speed switch 8 and load 9.

The device works as follows.

At nom. In flax mode, the signal is proportional to the rate of change of the voltage of source 1 and load currents 9 are separated by sensors 2 and 4 and the converter is converted to pins 3 and 5. The output signals of these converters are fed to the input of an SINGLE OR circuit, implementing modulo two logic addition. At the exit of this

Editor A. Kozoriz

Compiled by I. Nazatzkika Tehred L. Serdyukova

Order 2749/34 Circulation 436 Sub-list

 USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab.,

Production and printing company, Uzhgorod, Projecto st., 4

328252

the signal circuit is equal to the bullet, since the inputs to the inputs are the same) 1e signals. Switch 8 is not turned on, since the signal at its input and at output 5 of amplifier 7 is zero.

A sharp increase in voltage at the output of source 1, to which load 9 is connected, does not turn on switch 8, since 10 signals, sensors from sensors 2 and 4 increase in proportion to the rate of increase in voltage and load current. These signals are converted to a logical 1 and the output of the circuit is EXCLUDED - 15 NOE or the signal is zero. In this connection, the high-speed switch B is not turned on and the supply voltage is still applied to the load 9.

20 In the case of switching (emergency operating load) 9, the signal from sensor 2 is increased, since overvoltage occurs at the output of source 1, and the signal from sensor 4 is reduced. Therefore, the output of the converter 3 will be logical 1, and the output; converter 5 - logical O. The presence of two different signals at the input of the circuit EXCLUDED OR

30 causes a signal to appear at its output, which is amplified by amplifier 7 and fed to the input of a high-speed switch 8, which operates and turns off source 1.

, g If the output or load is shorted, the voltage at the output of source 1 decreases, and the current through sensor 4 increases. A decrease in voltage leads to the fact that one input is a circuit; ELIMINATED OR is a logical O, from converter 3, and to the second input of the circuit is logical 1, since the signal from sensor 4 increases / j. The presence of two different signals at the circuit input EXCLUDED OR results in the appearance of a signal at its output and, as in the previous case, to turn on the switch 8.

Corrector T, Kolb

Claims (1)

METHOD OF INSURING SAFETY of electrical circuits, based on the simultaneous isolation of signals proportional to the rate of change of current and voltage in the circuit, by which the power source is switched off, characterized in that, in order to increase the reliability of intrinsically safe systems, signals proportional to the rate of change of current and voltage circuits are converted into digital form: for example, when increasing - into logical 1, and when decreasing - into logical 0, and the trip control signal is generated by the addition of the received signals modulo two.