CN107978121B - Reusable linear temperature-sensing fire detector and alarm method thereof - Google Patents
Reusable linear temperature-sensing fire detector and alarm method thereof Download PDFInfo
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Abstract
The invention discloses a linear reusable linear temperature-sensing fire detector and an alarm method thereof, wherein the detector consists of a detection cable, a signal processor and a terminal processor which are respectively connected to two ends of the detection cable, the detection cable is formed by twisting two detection core wires which are made of conductors with positive temperature coefficient materials, one detection conductor is covered with an NTC characteristic barrier layer, and the other detection conductor is covered with a fusible insulating layer; the signal processor comprises a signal processing circuit change-over switch, the terminal processor comprises a matching resistance change-over switch, the I-path signal processing circuit is connected with the I-path terminal matching resistance or the II-path signal processing circuit is connected with the II-path terminal matching resistance through the matching of the two switches, so that the impedance of the positive temperature coefficient material and the impedance of the negative temperature coefficient material are detected respectively, the signal processor analyzes and calculates the measured impedance, the running state of the detector is judged, and when a fault or fire state occurs, the corresponding alarm is triggered.
Description
Technical Field
The invention belongs to the field of public safety fire protection, and particularly relates to a reusable linear temperature-sensing fire detector alarm device and an alarm method thereof.
Background
At present, cable type linear temperature-sensing fire detectors are widely applied in the field of industrial fire protection. Taking a restorable linear temperature-sensing fire detector as an example, the restorable linear temperature-sensing fire detector consists of a terminal resistor, a temperature-sensing cable and a microcomputer processing device, wherein the temperature-sensing cable is formed by twisting two conductors coated with NTC (Negative Temperature Coefficient ) characteristic materials; the microcomputer processing device is connected with the temperature sensing cable; when the temperature of a certain part of the temperature sensing cable is increased, the resistance value between the two conductors is reduced, and when the resistance value is reduced to a set threshold value, the microcomputer processing device sends out a fire alarm signal. However, the alarm temperature of the detector is related to the heated length, the ambient temperature and the use length of the detection cable, and false alarm is easy to generate in a high-temperature environment.
In chinese patent No. 200510114820.4, an analog line type fixed temperature fire detection cable is disclosed, which is composed of two parallel detection conductors, an NTC characteristic blocking layer and a fusible insulation layer, wherein the NTC characteristic blocking layer and the fusible insulation layer are disposed between the two detection conductors to separate the detection conductors. Further, one of the two detection conductors is a carbon spring steel wire coated NTC special type barrier layer, and the other detection conductor is a carbon steel wire coated meltable insulating layer. When the detecting cable is heated, the temperature of the detecting cable rises along with the temperature rise, and when the temperature does not reach the softening (or melting) temperature area of the fusible insulation layer, the two detecting conductors are insulated; when the heated temperature of the detection cable continues to rise and reaches the melting temperature of the fusible insulation layer, the fusible insulation layer is melted or softened, the deformation stress existing between the two detection conductors eliminates the insulation resistance of the fusible insulation layer between the two detection conductors of the heated part of the detection cable, the detection cable is converted into a common NTC analog line type constant temperature fire detection cable, the resistance between the two parallel conductors is reduced along with the rise of the temperature, and the constant temperature alarm is carried out according to the resistance or the change of other electrical parameters caused by the change of the resistance. The analog line type constant temperature fire detection cable eliminates the influence of the use length of the detection cable and the ambient temperature on the alarm temperature by introducing the fusible insulation layer. However, the detector has certain defects, especially when the detector is applied to a scene of high temperature easily generated by a transformer, a belt conveyor or a locomotive, and the like, after the whole length of the detector is heated or most of the length of the detector is heated for alarming, a meltable insulating layer covered outside one detection conductor is completely destroyed, and the whole length or most of the detection cable is converted into a common NTC analog line type constant temperature fire detection cable, so that the detector still has higher false alarm rate.
Due to the existence of the problems, the application range of the cable type linear temperature-sensing fire detector in the prior art is greatly limited.
Disclosure of Invention
The invention aims to: in order to solve the above problems, the present invention proposes a long-distance reusable line-type heat fire detector capable of providing good stability and sensitivity.
The invention also provides an alarm method of the linear temperature-sensing fire detector which can be repeatedly used in a long distance.
The technical scheme is as follows: a reusable line-type temperature-sensing fire detector comprises a signal processor, a terminal processor and a detection cable, wherein the detection cable is formed by twisting two detection core wires, the two detection core wires are made of conductors made of positive temperature coefficient materials, one detection conductor is covered with an NTC characteristic blocking layer, and the other detection conductor is covered with a fusible insulating layer. The head ends of the two core wires of the detection cable are respectively connected with terminals DW1 and DW2 in the signal processor, and the tail ends of the two core wires are also respectively connected with terminals DW3 and DW4 in the terminal processor.
The signal processor comprises a head end operation processing device, and an I-path signal processing circuit, a II-path signal processing circuit, a signal processing circuit change-over switch, a wireless signal generator and an alarm output circuit which are all connected with the head end operation processing device, wherein the signal processing circuit change-over switch is a gating switch which is alternatively selected, and can be switched and connected to the I-path signal processing circuit or the II-path signal processing circuit. The terminal processor comprises a terminal operation processing device, a wireless signal receiver and a matching resistance change-over switch which are connected with the terminal operation processing device, wherein the matching resistance change-over switch is a two-way or one-way gating switch and can be switched and connected to an I-way terminal matching resistor or an II-way terminal matching resistor. The I-path signal processing circuit is connected with the I-path terminal matching resistor or the II-path signal processing circuit is connected with the II-path terminal matching resistor through a signal processing circuit change-over switch in the signal processor and a matching resistor change-over switch in the terminal processor. The I-path signal processing circuit and the I-path terminal matching resistor are used for measuring PTC variation, and the resistance is smaller (between 1 omega and 1 Komega). The II-path signal processing circuit and the II-path terminal matching resistor are used for measuring NTC changes among wires, and the resistance value is large (between 1MΩ and 100MΩ, and is determined according to NTC characteristics).
The structure of the I-path signal processing circuit and the II-path signal processing circuit in the signal processor is the same, and each path of signal processing circuit consists of a conversion circuit, a first filter shaping circuit, a first follower, a 1-stage amplifying circuit, a filter, a PWM generator, a second filter shaping circuit (which is a PWM filter circuit), a second follower, a subtracter, a 2-stage amplifying circuit and an AD conversion circuit. The switching circuit, the first filter shaping circuit, the first follower, the 1-stage amplifying circuit and the filter are sequentially connected, the PWM generator, the second filter shaping circuit and the second follower are sequentially connected, the filter and the second follower are both connected to the subtracter, the subtracter is connected to the 2-stage amplifying circuit again, and the last 2-stage amplifying circuit is connected with the AD switching circuit. After impedance information is detected, the impedance information is converted into a voltage signal through a conversion circuit, the voltage signal is processed through a first filtering shaping circuit, a first follower, a 1-stage amplifying circuit and a filter, and then is mixed with PWM signals generated by a PWM generator and processed through a PWM filtering circuit and a second follower in a subtracter, and then the voltage signal enters a 2-stage amplifying circuit for amplification, and the amplified signals are subjected to analog-to-digital conversion through an AD conversion circuit.
The implementation process of the switching of the signal processing circuit is as follows: the head end operation processing device in the signal processor sends a switching instruction to the wireless signal receiver in the terminal processor through the wireless signal generator; after receiving the switching instruction, a wireless signal receiver in the terminal processor starts a matching resistance switching switch to switch a corresponding loop through a terminal operation processing device, and simultaneously feeds back a confirmation signal to a head end operation processing device; after receiving the confirmation signal, the head-end operation processing device realizes the switching of the signal processing circuit through a signal processing circuit switching switch.
An alarm method using the reusable line-type temperature-sensing fire detector comprises the following steps:
1) Signal quantity acquisition and processing: the head-end arithmetic processing device detects the impedance of the positive temperature coefficient material and the negative temperature coefficient material in a time-sharing mode, stores impedance data, and calculates the temperature state around the detection cable according to the characteristic curve of the material impedance and the temperature.
When the impedance of the positive temperature coefficient material is detected, a signal processing circuit switch is switched to an I-path signal processing circuit, a matching resistance change-over switch is switched to an I-path terminal matching resistance, two core wires of a detection cable are connected into the I-path signal processing circuit, impedance information is converted into a voltage signal through a conversion circuit, interference signals are filtered through a filtering shaping circuit, the voltage signal is buffered and isolated by a follower and then enters a 1-stage amplifying circuit, the voltage signal is filtered again by a filter and then enters a subtracter together with PWM signals which are isolated by shaping and filtering, an output signal of the 1-stage amplifying circuit is translated and then enters a 2-stage amplifying circuit, and signals amplified by the 2-stage amplifying circuit enter an AD conversion circuit for conversion and are judged by a head-end operation processing device after conversion;
when the impedance of the negative temperature coefficient material is detected, the signal processing circuit switch is switched to a second-path signal processing circuit, the matching resistance change-over switch is switched to a second-path terminal matching resistance, and the second-path signal processing circuit is processed through devices such as a subsequent filter shaping circuit, a follower, an amplifying circuit and the like, and the signal processing process is the same as that of the positive temperature coefficient material.
2) And (3) alarm judgment: the head-end operation processing device analyzes and processes the impedance of the positive temperature coefficient material and the impedance of the negative temperature coefficient material, judges the working state of the detector based on the impedance value, and immediately triggers the alarm output circuit to alarm correspondingly when a fault or a fire disaster occurs.
Wherein, the fault alarm includes: when the I-path terminal matching resistor is connected with the I-path signal processing circuit or the II-path terminal matching resistor is connected with the II-path signal processing circuit, if the resistance value acquired by the head-end operation processing device is far smaller than the terminal matching resistance value or tends to 0, judging that the detection core wire is short-circuited, and outputting fault alarm information; if the acquired terminal resistance value is approximately + -infinity, judging that the detection core wire is broken, and outputting fault alarm information.
Fire alarms include two things: when the fire alarm device is used for the first time, after the head-end operation processing device in the signal processor detects that the impedance value of the NTC material is reduced to a certain threshold value N1, the signal processor sends out a fire alarm signal;
when the fusible insulation material is continuously used after being fully or partially fused, the variation of the resistance value of the PTC material is multiplied by a coefficient K to compensate the variation of the resistance value of the NTC material caused by the change of the ambient temperature, and when the variation of the resistance value of the PTC material is detected to be insufficient to compensate the variation of the resistance value of the NTC material, a fire alarm signal is sent out.
The beneficial effects are that: the linear temperature-sensing fire detector comprises a signal processing circuit change-over switch in a signal processor, a matching resistance change-over switch in a terminal processor, and the matching of the two switches is used for realizing that an I path of signal processing circuit is connected with an I path of terminal matching resistance or an II path of signal processing circuit is connected with an II path of terminal matching resistance so as to respectively detect the impedance of a positive temperature coefficient material and a negative temperature coefficient material, the signal processor analyzes and calculates the detected impedance, the running state of the detector is judged, and an alarm signal is triggered when the fire state occurs. After the whole length of the detection cable is heated or most of the length of the detection cable is heated for alarming, even if the fusible insulation layer covered outside one detection conductor is completely destroyed, the detection cable is converted into a common NTC analog line type constant temperature fire detection cable, and the detection cable can still accurately alarm through reasonable operation treatment.
Drawings
FIG. 1 is a block diagram of the overall system of a reusable linear heat fire detector according to the present invention;
FIG. 2 is a block diagram of the signal processing circuitry of FIG. 1;
FIG. 3 is a block diagram of the detection cable of FIG. 1;
FIG. 4 is a flow chart of a method for alerting using the detector of the present invention.
Detailed Description
The technical scheme of the invention is further described below with reference to the accompanying drawings.
Referring to fig. 1, a long-distance reusable line-type temperature-sensing fire detector is composed of a signal processor, a terminal processor and a detection cable, wherein the signal processor comprises an I-path signal processing circuit, a II-path signal processing circuit, a signal processing circuit change-over switch, a head-end operation processing device, a wireless signal generator and an alarm output circuit; the terminal processor comprises a I-path terminal matching resistor, a II-path terminal matching resistor, a matching resistor change-over switch, a terminal operation processing device and a wireless signal receiver. The two signal processing circuits have the same structure, and as shown in fig. 2, the I signal processing circuit comprises an I conversion circuit, an I first filter shaping circuit, an I first follower, an I1 stage amplifying circuit, an I filter, an I PWM generator, an I second filter shaping circuit, an I second follower, an I subtractor, an I2 stage amplifying circuit and an AD conversion circuit; the II-path signal processing circuit comprises a II-path conversion circuit, a II-path first filter shaping circuit, a II-path first follower, a II-path 1-stage amplifying circuit, a II-path filter, a II-path PWM generator, a II-path second filter shaping circuit, a II-path second follower, a II-path subtractor, a II-path 2-stage amplifying circuit and an AD conversion circuit. In each signal processing circuit, a conversion circuit, a first filter shaping circuit, a first follower, a 1-stage amplifying circuit and a filter are sequentially connected, a PWM generator, a second filter shaping circuit and a second follower are sequentially connected, the filter and the second follower are connected to a subtracter, the subtracter is connected to a 2-stage amplifying circuit, and finally the 2-stage amplifying circuit is connected with an AD conversion circuit.
Referring to fig. 3, the detection cable is formed by twisting two detection core wires, both of which are made of conductors of positive temperature coefficient material, one detection conductor is covered with an NTC characteristic blocking layer, and the other detection conductor is covered with a fusible insulation layer. When the detector is used, the head end and the tail end of two core wires of the detection cable are respectively connected with the DW1 terminal and the DW2 terminal of the signal processor; DW3 and DW4 terminals of the terminal processor. The I-path signal processing circuit is connected with the I-path terminal matching resistor or the II-path signal processing circuit is connected with the II-path terminal matching resistor through a signal processing circuit change-over switch in the signal processor and a matching resistor change-over switch in the terminal processor. The I-path signal processing circuit is used for detecting the impedance of the positive temperature coefficient material, and the II-path signal processing circuit is used for detecting the impedance of the negative temperature coefficient material. The head-end operation processing device is used for detecting the impedance of the positive temperature coefficient material and the negative temperature coefficient material in a time-sharing way, analyzing and operating the impedance value, judging the running state of the detector according to the temperature characteristic curve of the material, and triggering the alarm output circuit to output a fault or alarm signal if the running state is a fault or fire state.
With continued reference to fig. 1 and 2, when the impedance of the ptc material is detected, the signal processing circuit switch is switched to the i-path signal processing circuit and the matching resistance switch is switched to the i-path termination matching resistance. The two core wires are connected with an I-path terminal matching resistor into an I-path signal processing circuit, impedance information is converted into a voltage signal through an I-path conversion circuit, an I-path first filtering shaping circuit filters interference signals, the interference signals enter an I-path 1-level amplifying circuit after being buffered and isolated by a first follower, amplified signals are filtered by an I-path filter and enter an I-path subtracter for mixing with an I-path PWM signal processed and isolated by an I-path second filtering shaping circuit and the first follower, and the output signals of the 1-level amplifying circuit are translated and enter an I-path 2-level amplifying circuit. The signal translation aims to enable the signal to be in a reasonable interval, if the voltage value of the signal is too high, the operational amplifier can be saturated, and if the amplification factor is too small, the resistance change can not be acquired. The signals after two-stage amplification enter an AD conversion circuit to be converted, and the analog quantity is converted into the digital quantity, so that the voltage value corresponding to the core wire impedance is obtained. The converted voltage value is stored in the head-end operation processing device for judgment.
When the impedance of the negative temperature coefficient material is detected, the signal processing circuit switch is switched to the II-path signal processing circuit, and the matching resistance change-over switch is switched to the II-path terminal matching resistance. The two core wires are connected with a II-path terminal matching resistor into a II-path signal processing circuit, impedance information is converted into a voltage signal through a II-path conversion circuit, interference signals are filtered by a II-path first filtering shaping circuit, the interference signals are buffered and isolated by a first follower and then enter a II-path 1-level amplifying circuit, amplified signals are filtered by a II-path filter and then enter a II-path subtracter together with II-path PWM signals processed and isolated by a II-path second filtering shaping circuit and a second follower, and output signals of the 1-level amplifying circuit are translated and then enter a II-path 2-level amplifying circuit. The signals after two-stage amplification enter an AD conversion circuit to be converted, and the converted signals are stored in a head-end operation processing device for judgment.
The implementation process of the switching of the signal processing circuit is as follows: the head end operation processing device in the signal processor sends a switching instruction to the wireless signal receiver in the terminal processor through the wireless signal generator; after receiving the switching instruction, a wireless signal receiver in the terminal processor starts a matching resistance switching switch to switch a corresponding loop through a terminal operation processing device, and simultaneously feeds back a confirmation signal to a head end operation processing device; after receiving the confirmation signal, the head-end operation processing device realizes the switching of the signal processing circuit through a signal processing circuit switching switch.
When the detector is used, the head-end operation processing device collects the positive temperature coefficient material impedance and the negative temperature coefficient material impedance in a time-sharing mode, analyzes and calculates in real time, and immediately triggers the alarm output circuit to alarm correspondingly when a fault or a fire disaster occurs. Specifically, when two detection core wires short circuit occurs, the terminal resistance value acquired by the I and II paths of the detection core wires is far smaller than the terminal matching resistance value, and the normal value is as follows: the I path approximates the PTC material resistance plus the I path termination resistance, the II path approximates the NTC material resistance plus the II path termination resistance. In particular, if the resistance value acquired by the head-end arithmetic processing device is 0 or tends to 0, it is judged that a short circuit occurs. When the two detection core wires are broken, the terminal resistance values acquired by the corresponding I and II paths are in theory + -infinity. When the above situation occurs, the alarm output circuit outputs a fault state to remind an operator on duty to overhaul the fault immediately.
Referring to fig. 4, the implementation process of the fire alarm is as follows:
1. the temperature sensing cable is used for the first time:
the working principle is as follows: when the NTC measuring circuit is switched to, the two PTC core wires are isolated by an insulating fusible material, and the resistance value between the two detected core wires is the II-path terminal matching resistance value N0. The software only determines the NTC variation at this time. When the temperature rises to the melting point of the meltable material, the meltable material melts. The two PTC core wires are separated by NTC material, and the resistance of the NTC material is reduced due to temperature rise. After the meltable material is melted, the resistance between the two PTC core wires is instantaneously reduced, and when the head-end operation processing device in the signal processor detects that the resistance of the NTC material is reduced to a certain threshold value N1, the signal processor sends out an alarm signal.
The specific implementation is as follows: after the signal processor is electrified, a switching signal is sent to the terminal processor through the wireless signal generator, and the terminal processor responds after waiting for a certain time. After the signals are stable, the current positive temperature coefficient material impedance P and the negative temperature coefficient material impedance N are collected in real time, data are stored in a ROM array of the signal processor, and the first collected positive temperature coefficient material impedance P0 and negative temperature coefficient material impedance N0 are stored independently. When a fire disaster occurs, the temperature around the temperature-sensing cable reaches the melting point of the fusible insulating material, the fusible insulating material is softened or melted, and the conductor of the positive temperature coefficient material wrapping the fusible insulating material is directly contacted with the NTC material under the action of elasticity. The resistance between the two positive temperature coefficient conductors is instantaneously reduced to N1, and the signal processor sends out a fire alarm signal.
2. After full length or partial melting of the meltable insulating material:
the working principle is as follows: when the detector alarm linkage starts the corresponding fire extinguishing equipment to extinguish fire, the PTC core wire in the original meltable material is directly contacted with the NTC material. When the temperature around the temperature sensing cable is reduced, the NTC impedance between the two PTC core wires can be restored to a higher value. Because the barrier of the meltable insulating material is lacking between the two PTC core wires, the resistance between the PTC core wires is related to the heated length, the ambient temperature and the use length, and false alarm is very easy to generate when the ambient temperature changes. When the signal processor is powered on again and is switched to the NTC measuring circuit, the resistance value detected between the two PTC core wires is the parallel connection value of the II-path terminal matching resistor and the NTC material. The value must be less than the termination matching resistance N0. The PTC change is then introduced as compensation. In a certain temperature range, the higher the temperature is, the faster the resistance change rate of the NTC material is; the resistance change of the PTC material is approximately in linear relation with temperature. According to the temperature and impedance characteristic curve difference of the NTC and PTC materials, the variation of the NTC due to the environmental temperature is compensated.
The specific implementation is as follows: after the signal processor is electrified, a switching signal is sent to the terminal processor through the wireless signal generator, and the terminal processor responds after waiting for a certain time. After the signals are stable, the current positive temperature coefficient material impedance P and the negative temperature coefficient material impedance N are collected in real time, data are stored in a ROM array of the signal processor, and the first collected positive temperature coefficient material impedance P0 'and negative temperature coefficient material impedance N0' are independently stored. Because the fusible insulation material is compromised, N0' is less than N0. The head-end operation processing device can judge whether the fusible insulation material of the temperature sensing cable is fused according to the temperature sensing insulation material. If the damage length of the meltable insulating material is longer, when the ambient temperature is increased or sunlight is directly irradiated, the NTC resistance value can be reduced along with the temperature increase, and the NTC alarm condition is very easy to be reached to cause false alarm. In this case, the PTC change amount should be combined with the NTC change amount judgment. The invention adopts the PTC material resistance change quantity multiplied by a coefficient K (determined by experiments) to compensate NTC change quantity caused by environmental temperature change. When the temperature rises to a higher temperature, the change rate of the impedance value of the NTC material is accelerated, the change amount of the impedance value of the PTC material is insufficient to compensate the change amount of the impedance value of the NTC material, and accordingly the signal processor gives out a fire alarm.
Claims (4)
1. The reusable linear temperature-sensing fire detector is characterized by comprising a detection cable, a signal processor and a terminal processor, wherein the signal processor and the terminal processor are respectively connected to two ends of the detection cable, the detection cable is formed by twisting two detection core wires, each detection core wire is made of a conductor with positive temperature coefficient, one detection conductor is covered with an NTC characteristic blocking layer, and the other detection conductor is covered with a fusible insulating layer;
the signal processor comprises a head end operation processing device, and an I-path signal processing circuit, a II-path signal processing circuit, a signal processing circuit change-over switch, a wireless signal generator and an alarm output circuit which are all connected with the head end operation processing device, wherein the signal processing circuit change-over switch is switchably connected to the I-path signal processing circuit or the II-path signal processing circuit;
the I-path signal processing circuit and the II-path signal processing circuit comprise a conversion circuit, a first filter shaping circuit, a first follower, a 1-stage amplifying circuit, a filter, a PWM generator, a second filter shaping circuit, a second follower, a subtracter, a 2-stage amplifying circuit and an AD conversion circuit, wherein the conversion circuit, the first filter shaping circuit, the first follower, the 1-stage amplifying circuit and the filter are sequentially connected, the PWM generator, the second filter shaping circuit and the second follower are sequentially connected, the filter and the second follower are both connected to the subtracter, the subtracter is connected to the 2-stage amplifying circuit, and the 2-stage amplifying circuit is connected with the AD conversion circuit;
the terminal processor comprises a terminal operation processing device, a wireless signal receiver and a matching resistance change-over switch which are connected with the terminal operation processing device, wherein the matching resistance change-over switch is switchably connected to an I-path terminal matching resistor or an II-path terminal matching resistor;
the alarming method of the linear temperature-sensing fire detector comprises the following steps:
signal quantity acquisition and processing: the head-end operation processing device in the signal processor detects the impedance of the positive temperature coefficient material and the negative temperature coefficient material in a time-sharing mode, stores impedance data, and calculates the temperature state around the detection cable according to the characteristic curve of the material impedance and the temperature;
and (3) alarm judgment: the head-end operation processing device analyzes and processes the impedance of the positive temperature coefficient material and the impedance of the negative temperature coefficient material, judges the working state of the detector based on the impedance value and the impedance value change trend, and triggers the alarm output circuit to output a corresponding alarm signal if the detector is in a fault state or a fire state;
when the impedance of the positive temperature coefficient material is detected, a signal processing circuit switch in the signal processor is switched to an I-path signal processing circuit, a matching resistance change-over switch in the terminal processor is switched to an I-path terminal matching resistance, and two core wires of the detection cable connect the I-path terminal matching resistance into the I-path signal processing circuit;
when the impedance of the negative temperature coefficient material is detected, a signal processing circuit switch in the signal processor is switched to a II-path signal processing circuit, a matching resistance change-over switch in the terminal processor is switched to a II-path terminal matching resistance, and two core wires of the detection cable connect the II-path terminal matching resistance into the II-path signal processing circuit;
after impedance information is detected under the two conditions, the impedance information is processed in the same process, and the method comprises the following steps: the impedance information is converted into a voltage signal through a conversion circuit, an interference signal is filtered through a first filtering shaping circuit, the interference signal is buffered and isolated by a first follower and then enters a 1-stage amplification circuit, the interference signal is filtered again by a filter and then enters a subtracter together with a PWM signal which is isolated through shaping and filtering, an output signal of the 1-stage amplification circuit is translated and then enters a 2-stage amplification circuit, and a signal amplified by the 2-stage amplification circuit enters an AD conversion circuit for conversion and is converted and then is judged by a head-end operation processing device.
2. The line-type temperature-sensing fire detector of claim 1, wherein the signal quantity acquisition process comprises a signal processing circuit switching step, and the implementation process is as follows: the head end operation processing device in the signal processor sends a switching instruction to the wireless signal receiver in the terminal processor through the wireless signal generator; after receiving the switching instruction, a wireless signal receiver in the terminal processor starts a matched resistance change-over switch to switch a corresponding loop through a terminal operation processing device connected with the wireless signal receiver, and simultaneously feeds back a confirmation signal to a head end operation processing device; after receiving the confirmation signal, the head-end operation processing device realizes the switching of the signal processing circuit through a signal processing circuit switching switch connected with the head-end operation processing device.
3. The line-type heat fire detector of claim 1, wherein the fault alarm comprises: when the I-path terminal matching resistor is connected with the I-path signal processing circuit or the II-path terminal matching resistor is connected with the II-path signal processing circuit, if the resistance value acquired by the head-end operation processing device is smaller than or equal to the normal value minus the terminal matching resistance value, judging that the detection core wire is short-circuited, and outputting fault alarm information; if the acquired terminal resistance value is approximately + -infinity, judging that the detection core wire is broken, and outputting fault alarm information.
4. The line-type heat fire detector of claim 1, wherein the fire alarm judgment comprises:
when the fire alarm device is used for the first time, after the head-end operation processing device in the signal processor detects that the impedance value of the NTC material is reduced to a certain threshold value N1, the signal processor sends out a fire alarm signal;
when the fusible insulation material is continuously used after being fully or partially fused, the variation of the resistance value of the PTC material is multiplied by a coefficient K to compensate the variation of the resistance value of the NTC material caused by the change of the ambient temperature, and when the variation of the resistance value of the PTC material is detected to be insufficient to compensate the variation of the resistance value of the NTC material, a fire alarm signal is sent out.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711470380.5A CN107978121B (en) | 2017-12-29 | 2017-12-29 | Reusable linear temperature-sensing fire detector and alarm method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201711470380.5A CN107978121B (en) | 2017-12-29 | 2017-12-29 | Reusable linear temperature-sensing fire detector and alarm method thereof |
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| CN107978121A CN107978121A (en) | 2018-05-01 |
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