JPH0139160B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a centralized gas leak monitoring system, particularly a gas leak centralized monitoring system in which a terminal of a gas leak alarm and a central monitoring panel are connected by a two-wire line. This invention relates to a gas leak centralized monitoring system that detects an abnormal state of a gas leak alarm and a line by transmitting a search pulse signal from the side and receiving a response signal.

In the conventional gas leak centralized monitoring system, the gas leak alarm terminal and the central monitoring panel are connected by a two-wire line.
Even if it is possible to identify whether the gas leak alarm is in normal condition with no gas leak or no gas leak, it is impossible to detect whether the power to the gas leak alarm is normally applied or whether the above line is disconnected. It was possible. Above 4
In the case of detecting the state of gas leakage and the state of no gas leakage of the gas leakage alarm, the presence/absence of power supply to the gas leakage alarm, and the presence/absence of disconnection of the line, A three-wire line was used to connect the gas leak alarm terminal and the central monitoring panel to detect the four types of conditions listed above. Although it is possible to detect the operating state of the gas leak alarm itself with a two-wire line, it has the disadvantage that it cannot detect the state of power supply voltage applied to the gas leak alarm and the presence or absence of disconnection of the line. When detecting the state of power supply voltage applied to the gas leak alarm and whether or not the line is disconnected, a two-wire line cannot distinguish between these states, so a three-wire line must be used. There were some unavoidable flaws.

The present invention is aimed at solving the above-mentioned drawbacks, and is capable of detecting gas leakage in the above-mentioned four types by connecting the terminal of a gas leak alarm device and a central monitoring panel with a two-wire line. The purpose is to provide a centralized monitoring system. Therefore, the gas leak centralized monitoring system of the present invention includes a gas leak alarm whose output voltage is different between a gas leak and a normal state, and also connects the terminal of the gas leak alarm and these gas leak alarms. In a gas leak centralized monitoring system, which is equipped with a central monitoring panel for centralized management, and in which a terminal of the gas leak alarm and the central monitoring panel are connected by a two-wire system, the gas leak alarm is connected to the central monitoring panel. a pulse generator that sends a search pulse signal to the line to which the terminal is connected, the pulse generator having a peak value of the search pulse signal variable in accordance with the state of the gas leak alarm and the line;
A voltage limiting element is connected in series to the above line and receives a response signal that responds to the search pulse signal in accordance with the state of the gas leak alarm and the line, and the voltage limiting element receives the response signal by the current flowing through the voltage limiting element. The device is characterized in that it is equipped with a photo coupler for identifying signals, and is configured to detect the gas leak alarm, the application of power supply voltage to the gas leak alarm, and the presence or absence of line disconnection. This will be explained below with reference to the drawings.

Fig. 1 shows the circuit configuration of an embodiment of the central monitoring system according to the present invention, Fig. 2 A to D are explanatory diagrams of signal waveforms received by the central monitoring board, Fig. 3 shows the characteristic curve of the Zener diode, 4A to 4D show waveform explanatory diagrams of the output signal waveforms appearing at the output terminals of the centralized monitoring panel, respectively.

In FIG. 1, a terminal 3 of a gas leak alarm is connected to a central monitoring panel 1 via a two-wire line 2. A plurality of gas leak alarm terminals 3 are connected to the centralized monitoring panel 1 via respective two-wire lines 2, but in the figure, one gas leak alarm terminal 3 is shown as an example. is shown. The terminal 3 of the gas leak alarm includes a gas leak alarm 4 and diodes 5 and 6. When the gas leak alarm 4 is in a normal state, the gas leak alarm 4 has a DC voltage
Output V ₁ . In addition, when the gas leak alarm 4 detects a gas leak, the gas leak alarm 4
outputs a DC voltage V ₂ (V ₂ >V ₁ ). When the power supply voltage is not applied to the gas leak alarm 4, no output is output from the gas leak alarm 4.

As shown in the same figure, the centralized monitoring panel 1 is connected with a Zener diode 8 via a resistor 7 to the cathode sides of diodes 5 and 6 in the terminal 3 of the gas leak alarm, and a photo coupler 9. is grounded through. One end of the photo transistor of the photo coupler 9 is connected to a power source E, and the other end is grounded via an output resistor 10. An output terminal 11 is output from the output resistor 10, and an output is obtained in response to a response signal representing the state of the terminal 3 of the gas leak alarm.

A transformer 12 is connected to the anode sides of the diodes 5 and 6 in the terminal 3 of the gas leak alarm, and the other end is connected to It is grounded as shown in the figure. transformer 12 part 1
On the next side, resistors 13 and 14 are connected in parallel, and by switching the power supply voltage E with a switch 15, the peak value of the search pulse generated in the transformer 12 can be changed. The search pulse is generated by inputting a pulse signal to the base of the transistor 17 connected between the primary side of the transformer 12 and ground. Reference numeral 16 is an input terminal to which a pulse signal is input, and 18 represents a diode that allows the search pulse generated on the secondary side of the transformer 12 to flow in one direction.

The operation of the gas leak centralized monitoring system of the present invention configured as described above can be performed in four states: operation when the gas leak alarm 4 is not detecting a gas leak and is in a normal state; Operation when detecting gas leak, central monitoring panel 1
The operation when the two-wire line connecting the terminal 3 of the gas leak alarm and the terminal 3 of the gas leak alarm is disconnected, and the operation when the power supply voltage to the gas leak alarm 4 is not supplied. We will explain each of them.

() When the gas leak alarm does not detect a gas leak and is in a normal state The contact of the switch 15 is connected to the resistor 13 side, and by applying a pulse signal to the input terminal 16, the secondary of the transformer 12 A search pulse signal with a peak value Vp ₁ is generated on the side. The search pulse signal of Vp ₁ is sent to the terminal 3 of the gas leak alarm via the two-wire line 2. When the gas leak alarm 4 does not detect a gas leak, it outputs the DC voltage V ₁ as explained above, and the DC voltage V ₁ and the search pulse signal of Vp ₁ passing through the diode 6 are superimposed. A signal having a waveform as shown in FIG. will be returned to. Since the Zener diode 17 which receives the response signal through the resistor 7 has a characteristic curve as shown in FIG. 3, when the voltage of the response signal exceeds the Zener voltage Vz of the Zener diode 17, the photo coupler A large current flows through the diode 9, and on the other hand, the voltage of the response signal is the Zener voltage Vz.
When it is lower, the current flowing through the diode of photocoupler 9 is small. Therefore, a pulse signal as shown in FIG. 4A is outputted to the output terminal 11.

() When the gas leak alarm is detecting a gas leak As in case (), the contact of the switch 15 is connected to the resistor 13 side, and the pulse signal input to the input terminal 16 is applied. As a result, a search pulse signal having a peak value Vp ₁ is generated on the secondary side of the transformer 12. The search pulse signal of Vp ₁ is sent to the terminal 3 of the gas leak alarm via the two-wire line 2. When the gas leak alarm 4 detects a gas leak, it outputs the DC voltage V ₂ as explained above, and the DC voltage V ₂ is higher than the Zener voltage Vz of the Zener diode 8 (V ₂ > Vz). Therefore, the terminal 3 of the gas leak alarm outputs a signal having the waveform shown in FIG. 2B on which the search pulse signal of Vp ₁ is superimposed. That is, a signal having the waveform shown in FIG. 2B is sent back to the centralized monitoring board 1 as a response signal in response to the search pulse signal emitted from the transformer 12 via the two-wire line 2. The voltage of the response signal is the Zener diode 8
Since the zener voltage Vz is larger than the zener voltage Vz, the current flowing through the diode of the photo coupler 9 is large, a saturation current flows through the photo transistor of the photo coupler 9, and an almost constant voltage is applied to the output terminal 11 as shown in FIG. 4B. signal is output.

() When the two-wire line connecting the central monitoring panel and the terminal of the gas leak alarm is disconnected The contact of the switch 15 is connected to the resistor 13 side, and the input terminal 16 By applying the pulse signal, the secondary side of the transformer 12 has a peak value Vp ₁
A search pulse signal is generated. The search pulse signal of Vp ₁ is sent to the terminal 3 of the gas leak alarm via the two-wire line 2;
is disconnected at any point, central monitoring board 1
As shown in FIG. 2C, no signal is returned in response to the search pulse signal emitted from the transformer 12. Therefore, no current flows through the diode of the photo coupler 9, and no signal is output to the output terminal 11 as shown in FIG. 4C. Therefore, the contact of the switch 15 is connected to the resistor 14 side, and the transformer 12
A search pulse signal with a peak value Vp ₂ (Vp ₂ >Vz) is generated on the secondary side of. The Vp ₂ search pulse signal is sent to the terminal 3 of the gas leak alarm via the 2-wire line 2.
However, since the two-wire line 2 is disconnected at one of the lines, the central monitoring board 1 receives the same message as above.
No response signal is obtained in response to the search pulse signal of Vp ₂ , and no signal is output to the output terminal 11 as shown in FIG. 4C. That is, no matter which side of the resistors 13 and 14 the contact of the switch 15 is connected to, if no output is obtained at the output terminal 11, this indicates that the two-wire line is disconnected.

() When the power supply voltage is not being supplied to the gas leak alarm, connect the contact of switch 15 to the resistor 13 side, and generate a search pulse signal with peak value Vp ₁ from the secondary side of transformer 12. , the search pulse signal of Vp ₁ is sent to the terminal 3 of the gas leak alarm via the two-wire line 2. Since power supply voltage is not supplied to the gas leak alarm device 4, the gas leak alarm device 4
No output voltage is generated from , and the search pulse signal of Vp ₁ passes through the diode 6 and is returned to the central monitoring board 1 as a response signal from the terminal 3 of the gas leak alarm. The search pulse signal of Vp ₁ is
Since the voltage is lower than the zener voltage Vz of the diode 8, only a small amount of current flows through the diode of the photo coupler 9, as seen from the characteristic curve of the zener diode shown in FIG.
1, no output appears as shown in FIG. 4C.

Therefore, as in the case of () above, switch 15
is connected to the resistor 14 side, a search pulse signal with a peak value Vp ₂ is generated on the secondary side of the transformer 12, and sent out via the two-wire line 2 of the terminal 3 of the gas leak alarm. From the terminal 3 of the gas leak alarm, a search pulse signal with a peak value Vp ₂ is sent back to the central monitoring panel 1 as a response signal for the same reason as above. Since the response signal with peak value Vp ₂ is larger than the zener voltage Vz of the zener diode 8, the photo coupler 9
A strong and weak current flows through the diode. Therefore,
At the output terminal 11, a pulse signal as shown in FIG. 4D is obtained. That is, switch 15 is connected to resistor 1.
If the switch 15 is connected to the resistor 14 side and a pulse signal output appears at the output terminal 11, the power supply voltage will be applied to the gas leak alarm 4. This indicates a state in which no power is being supplied, and is distinguished from the state in () above where the two-wire line 2 is disconnected.

In this way, the resistor 13 or 1 of the switch 15
4 and the output appearing at the output terminal 11, if the gas leak alarm 4 is not detecting a gas leak and is in a normal state, the gas leak alarm 4 is detecting a gas leak. state, the two-wire line 2 connecting the central monitoring panel 1 and the terminal 3 of the gas leak alarm is disconnected, and the power supply voltage is supplied to the gas leak alarm 4. It is possible to identify the four states in which the device is not being used, and central monitoring becomes possible.

As explained above, according to the present invention, it is possible to monitor four states with a two-wire line, and one less wire is required compared to the conventional three-wire line, which simplifies the construction work and reduces wiring. Fewer wires are required.
Therefore, the total cost of the gas leakage central monitoring system is reduced.

[Brief explanation of drawings]

FIG. 1 shows the circuit configuration of an embodiment of the central monitoring system according to the present invention, FIGS. 2 A to D are waveform explanatory diagrams of signal waveforms received by the central monitoring board, and FIG. 3 shows the characteristic curve of the Zener diode. 4A to 4D show waveform explanatory diagrams of the output signal waveforms appearing at the output terminals of the centralized monitoring panel, respectively. 1... Central monitoring board, 2... 2-wire line, 3...
... Gas leak alarm terminal, 4... Gas leak alarm, 5, 6, 17... Diode, 7, 10, 1
3, 14...Resistor, 8...Zena diode,
9...Photo coupler, 11...Output terminal, 12
...Transistor, 15...Switch, 16...Input terminal, 17...Transistor.

Claims (1)

[Claims] 1.Equipped with a gas leak alarm whose output voltage is different when there is a gas leak and when it is normal, and 2. In a gas leak centralized monitoring system connected by a wired line, the central monitoring panel is equipped with a pulse signal generator that sends a search pulse signal to the line to which the gas leak alarm terminal is connected. a pulse generator whose peak value of the search pulse signal is variable in response to the state of the alarm and the line; and a pulse generator connected in series to the line that responds to the search pulse signal in response to the state of the gas leak alarm and the line. A gas leak alarm and a power supply to the gas leak alarm are provided with a voltage limiting element for receiving a response signal and a photo coupler for identifying the response signal by a current flowing through the voltage limiting element. A gas leak centralized monitoring system characterized by being configured to detect each state of voltage application and disconnection of a line.