SU812943A1 - Apparatus for automatic gas protection - Google Patents

Description

: 54) AUTOMATIC GAS SADWTbl DEVICE

one

The invention relates to means for automatically controlling the content of flammable gases in the air, namely, devices for automatically controlling methane and gas protection in coal mines.

The known equipment of automatic gas protection, which provides continuous monitoring of methane in mines, automatically disconnecting the power supply of the monitored object when the permissible concentration of methane in the controlled atmosphere reaches, transmitting continuous information on the concentration of methane and its registration with the dispatcher, supplying local and centralized sound and light alarm when reaching the maximum permissible concentration of methane til.

The disadvantage of this automatic gas protection equipment is the absence of the formation of commands for i-selective power outage depending on the duration and amplitude of exceeding the permissible level of methane in the mine atmosphere.

It is also known an automatic gas protection device, consisting

from the dispatcher console, the signaling apparatus, the executive unit of communication channels and sensors, control met.an, each of which contains converter elements, a bridge measuring circuit, a telemetric auto-compensation amplifier, a time relay, two phase-sensitive amplifiers and a power supply unit 12.

 A disadvantage of this device is the lack of selectivity of operation depending on the amplitude and duration exceeding up to 5 empty levels of methane.

The purpose of the invention is to ensure the selectivity of the operation of the device depending on the amplitude and duration of exceeding the permissible level of methane concentration.

This goal is achieved by the fact that one of the arms of the bridge measuring circuit of each sensor is inserted into a chain of two series-connected resistors with a ratio

5 resistances, proportional to the permissible and emergency levels of co-, mand, and parallel to the branch of the measuring bridge, a chain of synchronous adjustment of the sensor is activated

The rfoGTH levels of the executive commands, the output of which is connected to the inputs of phase-sensitive amplifiers, while the output of the phase-sensitive acceptable-level amplifier is via a time relay, and the output of the phase-sensitive emergency level amplifier is directly connected to the executive unit.

The drawing shows the block diagram of the device.

The device contains a methane control sensor, which includes a measuring unit 1, which in turn consists of a diode 2, a sensor control button for sensor 3, a calibrated resistor 4, an operating thermistor 5, and a thermistor compensating primary transformer elements included in the shoulders of a bridge measuring circuit, resistors 7 -10 ratios of the bridge measuring circuit, variable control resistors 11 and 12. Chain with an impedance ratio proportional to the allowable and alarm levels commands, formed by resistors 9 and 10, while the resistor 9 has a midpoint output. The ratio of the resistances of the resistors 9 and 10 is chosen so that the output of the bridge measuring circuit (the point between the resistors 5 and b and between the resistors 9 and 10) in the absence. methane was a signal equal in magnitude to the signal corresponding to the first (permissible) level. For the second output of the bridge, formed by the point between the resistors 5 and b and the midpoint of the output of the resistor 9, the ratio of the resistances of the part of resistor 9 and the sum of the other part of resistor 9 to resistor 10 is chosen so that at the output of the bridge, in the absence of methane, there is a signal equal in magnitude to the signal corresponding to the second (emergency) level.

The output of the bridge metering circuit is connected with a phase-sensitive amplifier 13 of the permissible (first) level and with a phase-sensitive amplifier 14 of the emergency (second) level. At the output of the phase-sensitive amplifier FU 13 of the permissible level, an intermediate executive unit 15 is installed, the output of the latter is connected to the input of a time relay 16, the output of which is connected to the input of the final execution unit 17. The output of the final execution unit is connected to the alarm apparatus 19 via a communication channel.

The output of the phase-effective amplifier 14 of the emergency level is directly connected to the final execution unit 17. All the sensor units are powered from the power supply unit 18.

A telemetric autocompensation amplifier 20 is also included in the measuring diagon of the bridge. The output of this amplifier is connected via a communication channel to the signaling device 19 and, through it, to the input of the dispatcher console 21.

Automatic gas device. Howl protection works as follows.

Methane content

in air is determined by the change in resistance of the operating thermistor resistor 5 using a bridge measuring circuit. The heat produced by the combustion of methane on the thermocatalytic converter element causes the resistance of the thermistor to rise and leads to the measurement of the unbalance of the bridge. In the absence of methane or its content below the permissible norm, the signal artificially created with the help of resistors 7-12, is fed to the input of two phase-sensitive amplifiers, ensuring the passage of current through the intermediate and final execution units. When the permissible concentration of methane in the controlled atmosphere is reached and exceeded, the output signal of the FU 13 decreases to

zero, while in the intermediate execution unit 15 a command is generated to turn on the time relay 16. If the concentration of methane is not reduced and is kept at a level not exceeding the permissible value of more than a certain value (for example, by 30%), then after a predetermined time delay (for example, 15-20 minutes), time relay 16 is activated and the final execution unit issues a command

to turn off the power, turn on the local light and sound alarms, transfer the corresponding discrete signal to the remote control. If in time

less than 15-20 minutes, the concentration of methane in a controlled atmosphere decreases below the permissible level, the command to turn off the power is not issued.

In the case when the methane concentration after reaching the permissible (first) level continues to grow and within less than 15-20 minutes it reaches the emergency (second) level, the signal at the output of the FU 14 becomes zero, and the time relay to the terminal execution unit 17 a signal is given that is instantly transformed into a power outage command and

alarm feed.

The main element of the chain of synchronous regulation is a belt resistor 12 which, directly or through additional

fixed resistors are connected

Claims (1)

Claim An automatic gas protection device consisting of a control room, an alarm apparatus, an executive unit, communication channels and methane control sensors, each of which contains converting elements, a bridge measuring circuit, a telemetric self-compensation amplifier, a time relay, two phase-sensitive amplifiers and a power supply unit, distinguishing with I mean that, in order to ensure the selectivity of the operation of the device depending on the amplitude and duration of exceeding the permissible concentration level Ana, one 5, from the shoulders of the bridge measuring circuit of each sensor, a chain of two series-connected resistors was introduced with a resistance ratio proportional to the permissible “Q and emergency command levels, and in parallel to the measuring bridge branch, a synchronous sensitivity control circuit of executive command levels is connected, the output of which is connected to the inputs of the phase-sensing device'5 amplifiers, while the output of the phase-sensitive amplifier of an acceptable level after £ barely time, and the output of the phase-sensitive amplifier At the top level, 20 are directly connected to the executive unit.