SU415687A1 - - Google Patents

Description

one

The present invention relates to the field of fire automatics.

A known method of monitoring the state of sensors, such as an alarm, is based on polling sensors.

The proposed method of monitoring the state of the sensors differs from the known method in that it sends polling pulses to all sensors at the same time, responds with sensor pulses at a given time interval and adds up, then the first and last response pulses are selected, their time shifts are measured relative to the specified time interval and on the sum of the sum of the response pulses and on the time shifts of the first and the last response 1 s pulses and on the change in the sensitivity of the sensor, its disturbance or its damage. This allows you to increase the speed control.

FIG. 1 shows the block diagram of the device that implements the proposed snob. The smoke detectors 1 are connected to the receiving station 2 by a two-wire communication line 3. The receiving station consists of a generator of 4 polling pulses, a device 5 for summing the response pulses, and an analyzer 6 for the response pulses. Each smoke sensor consists of a sensing element 7, a phase-shifting element 8 and a driver 9 response pulses.

FIG. Figure 2 shows the voltage graphs of currents, but they remove the proposed method.

Un - NRL: polling pulses sent by receiving station 2 to line 3;

(o) is the current of the response pulses of the sensors after summation;

/ is the level of the total response current pulse corresponding to the occurrence of the last response pulse of the sensor;

/ - current level corresponding to the appearance of the first response pulse of the sensor;

/ 1 - specified time interval.

On all graphs (Fig. 2) the passage

the first two polling pulses correspond to the initial state (absence of smoke and damage).

FIG. 3 shows one of the options made smoke detectors, which consists of

ionization chamber 10 with a radioactive isotope, a phase-shifting element-capacitor 11 and a response pulse generator — an electrometric thyratron 12 of a glowing discharge .- Shaper 4 sends

Inline 3 polling pulses / na sensor 1. Response pulses of the postal sensors and device 5 summation of response pulses. In the analyzer 6 response pulses, a total response is selected.

a pulse in order to isolate the first and the last pulse of the sensors and determine their time shifts.

Each polling pulse is sent simultaneously to all sensors 1 included in line 3. When a response pulse from all sensors is received during one polling pulse, analyzer 6 gives permission to driver 4 to send the next polling pulse.

When a polling pulse Un arrives at the sensor (see Fig. 3), the capacitor B starts charging through the ionization chamber 10. When the voltage on the capacitor 11 reaches the voltage of the electrolyte thyratron 12 on the control grid, the thyratron is ignited. This corresponds to the instant of response of the sensor. Thus, the response pulse of the sensor is shifted relative to the front edge of the interrogation pulse by the time interval corresponding to the charging time of capacitor 11 to the ignition voltage of the thyratron 12. In the absence of smoke and no damage, the response pulses of all sensors connected in parallel to line 3 are shifted by the same the specified time interval L using capacitors 11.

After the arrival of the response pulses of all the sensors, the polling pulse disappears (pause), the thyratrons of all the sensors go out, the capacitors 11 are discharged and all the sensors are reset.

With the appearance of smoke, the resistance of the ionization chamber 10 increases and, accordingly, the temporal shift of the response pulse of the sensor increases over a predetermined time interval.

If chamber 10 is damaged (insulation deterioration, water or dust entering the chamber gap), its resistance decreases and, accordingly, the sensor's sensitivity to smoke and the temporal shift of the response pulse of the sensor are reduced relative to the predetermined time interval. A decrease in the time shift of the response pulse will also occur if the capacitor I breaks or the thyratron 12 is damaged (the occurrence of a discharge between the electrodes of the thyratron in the absence of the control grid signal).

In case of damage to the radioactive source of chamber 10, the condenser I nrobo (unnumbered when a signal is applied to the control grid), the break in the connecting line, the response pulse of the sensor cannot appear.

Turning on the thyratron of the sensor (the appearance of a response pulse) increases the current in the line by some amount. Each response pulse of the sensor causes the same current increment in lily 3.

FIG. 2, a, b show the graphs of the polling pulses and the total response pulses for the three sensors in the case of smoke. The response pulses of the first two pulses

polling corresponds to the absence of smoke, since the response pulses of all three sensors arrived simultaneously at a specified time interval ti. In the third survey impulse B, one of the sensors did not hit the smoke, so

as its response impulse arrived at the time interval ti, smoke entered the other two sensors - their response impulses came at an interval of time and / s.

Due to the fact that in fire installations

The signaling task is to detect the maximum concentration of smoke in any of the sensors, then the pulse analyzer 6 selects the total response pulse according to the current value corresponding to the occurrence of the last response pulse, and measures its time shift. As seen in FIG. 2, a, the third polling pulse continues until time fa — the occurrence of the last response pulse.

FIG. Figures 2c, d show plots corresponding to a decrease in the sensitivity of one of the sensors when its response pulse appears before a predetermined time interval t.t.

The analyzer 6 selects by current I, corresponding to 1; the current amplitude of one response pulse, and determines its time shift. In this way, the sensitivity control is controlled.

at least one sensor.

FIG. 2, d, e, graphs are shown corresponding to the absence of a response pulse of one of the sensors as a result of damage to the sensors and / or the communication line. The absence of a response pulse is noted by the analyzer 6, since the total response pulse of the sensors cannot reach the current value / for a long time.

Subject invention

A method of monitoring the state of the sensors, an example of an alarm, based on polling the sensors, characterized in that, in order to increase the monitoring speed, the polling pulses are sent simultaneously to all the sensors, the response pulses of the sensors are shifted by a predetermined time interval and summed, then the first and the last response pulses measure them

time shifts relative to a given time interval and the value of c) mma response pulses and the time shifts of the first and last response pulses are judged to change the sensitivity of the sensor, its

outrage or damage.

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