JPH0353348Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a fire alarm system that monitors status changes intermittently without completely stopping the monitoring function when it is determined that a short circuit has occurred. Regarding equipment.

(Prior art) In a conventional fire alarm system, multiple fire detectors are connected to a pair of power signal lines drawn out from a receiver, and detection information from each fire detector is collected by calling using a polling method. was. That is, each fire detector sends back a response current in response to a call from the receiver, the receiver detects the response current from each fire detector with a current detection section, and based on the signal from the current detection section, Fire was detected, and if an excessive current flowed through the current detection unit, it was determined to be a short-circuit fault, and a protection function was activated at the same time as indicating the occurrence of the fault. That is, in order to prevent the current detection section from burning out due to excessive current, the power supply from the power supply section is prohibited. Therefore, the power supply to the fire detector is cut off, and the fire monitoring function of the system is stopped.

(Problem that the invention attempts to solve) However, even if a large current flows through the current detection section for a short period of time due to a temporary cause and the normal state is restored afterwards, the current detection section due to the temporary large current may The system determined that there was a short circuit failure based on the signal and immediately stopped the fire monitoring function, which caused the following problems.

In other words, when a short-circuit fault occurs, the person in charge of disaster prevention visually confirms the illumination of the fault light that indicates the occurrence of the fault, contacts maintenance personnel, and the maintenance personnel who rush to the scene check whether the monitoring function of the fire alarm system is normal. After confirming that the device is normal, the protection function of the device is canceled and fire monitoring is resumed. There was a problem where monitoring was forced to stop.

(Means for Solving the Problems) The present invention has been developed in view of the above problems.Even if a short-circuit fault occurs, the receiver A plurality of fire detectors are connected between a pair of power signal lines drawn out from the power supply section of the machine, the return current from the fire detectors is detected by the current detection section, and the detection information from the current detection section is detected. In the fire alarm device, the control unit determines information content based on the current detection unit, and the fire alarm system issues a fire alarm when the control unit determines a fire state, the receiver being configured to detect a short-circuit fault state based on the detection information from the current detection unit. A power cutoff section outputs a cutoff signal based on the determined control command from the control section, and switching means drives the power supply section intermittently by a switching operation based on the cutoff signal from the power cutoff section. , fire monitoring is conducted intermittently.

(Embodiment) FIG. 2 is an overall configuration diagram showing an embodiment of the present invention.

First, to explain the configuration, 1 is a receiver, and a plurality of fire detectors 2 are connected between a pair of power signal lines L1 and L2 drawn out from a power supply section built into the receiver 1, and fire monitoring is performed. . That is, each fire detector 2 has an address set in advance, and the receiver 1
In response to a call from the receiver 1, data is sent back to the receiver 1 in current mode.

FIG. 1 is a circuit diagram showing the internal configuration of the receiver 1 shown in FIG. P1 and P2 are power supply terminals, and a DC voltage E volt is applied between the terminals P1 and P2. A power supply section 4 is connected between the power supply lines drawn out from the terminals P1 and P2, and a pair of power supply signal lines L1 and L2 are drawn out through the power supply section 4. To explain the internal configuration of the power supply section 4, a transistor Q1, a Zener diode ZD1, and a transistor Q3 are connected in series between the power supply lines connected to the terminals P1 and P2. A Zener diode ZD2 is connected in parallel to the transistor Q3, and the base of the transistor Q3 is connected to the signal generator 5. Based on the output signal from the signal generator 5, the transistor Q3 performs a switching operation and turns on the Zener diode ZD2.・Turn off.
Here, the zener voltage of the zener diode ZD1 is set to V1, the zener voltage of the zener diode ZD2 is set to V2, and the DC voltage between the terminals P1 and P2 is set to E volts = V1 + V2, and the transistor Q3 By turning on and off the Zener diode ZD2 by the switching operation, a rectangular pulse superimposed on the voltage V1 is output between the pair of power supply signal lines L1 and L2. R1 is a resistor, and a current limiting circuit consisting of a transistor 2 and a resistor R2 is provided between the emitter and base of the transistor Q1. A resistor R3 is connected to the power source drawn out from the terminal P2, and detects the return current from the fire detector. 6 is a detection unit that detects the voltage change across the resistor R3 and converts the A/D
The converted detection information is output to the control section 7. The control section 7 determines the state based on the detection information from the detection section 6, and when it determines that there is a fire state, it drives the alarm section 8 and instructs an alarm display. When it is determined that it is in the normal monitoring state, the signal generator 5
is activated to command information collection from the fire detector 2. Further, when it is determined that there is a short-circuit failure state based on the detection information from the detection section 6, the power cut-off section 9 is driven and a command is given to send out a cut-off signal. The power cutoff section 9 outputs a rectangular pulse cutoff signal having a pulse interval t1 and a pulse width t2 based on a command from the control section 7. Here, the pulse interval t1 is t
1<<t2 and is set to be sufficiently shorter than the pulse width of the calling pulse so that each fire detector cannot distinguish it as a calling pulse. The cutoff signal from the power cutoff section 9 is applied to the base of the transistor Q4, causing the transistor Q4 to perform a switching operation. The collector of the transistor Q4 is connected to the base of the transistor Q1 forming the power supply section 4, and when the transistor Q4 is turned on,
Transistor Q1 is turned off by pulling the base of transistor Q1 to ground. That is, the transistor Q1 is turned on and off in accordance with the switching operation of the transistor Q4, and power is intermittently supplied between the pair of power supply/signal lines L1 and L2.

FIG. 3 is a signal waveform diagram of each part. The operation will be explained with reference to FIG. First, to explain the normal monitoring operation, the signal generating section 5 is driven based on a command from the control section 7, and a signal as shown in FIG. 3 is output. Transistor Q3 performs a switching operation based on the signal from signal generator 5, turning on/off twina diode ZD2. By turning on and off the twina diode ZD2, as shown in FIG. 3, the power supply unit 4 outputs a rectangular pulse superimposed on the DC voltage V1. This DC voltage V1 is used as a power source for the fire detector, and the DC voltage V1
The rectangular pulse superimposed on the signal becomes the call pulse for each fire detector. This calling pulse is output at predetermined time intervals, and the pulse interval between each pulse sets the return time of the return current from the corresponding fire detector. That is, as shown in FIG. 3, if a calling pulse n is output from the power supply section 4, the next calling pulse n+
The No. n fire detector that received the call within the return time up to 1 responds and returns data in current mode.

Next, if a large current flows through the resistor R3 due to a temporary cause, the control section 7 determines that a short-circuit fault condition exists based on the detection information from the detection section 6.
The control unit 7 drives the power cutoff unit 9 and instructs it to send out a cutoff signal. As shown in FIG. 3, when a cutoff signal from the power cutoff section 9 is applied to the base of the switching means Q4, the transistor Q4 performs a switching operation based on the cutoff signal. Transistor Q1 provided in power supply section 4 is turned on and off in accordance with the switching operation of transistor Q4. That is, as shown in FIG. 3, when the transistor Q1 is turned off, no voltage is supplied between the terminals P1 and P2, and the voltage becomes O volts between the pair of power supply signal lines L1 and L2. Furthermore, when the transistor Q1 is turned on, a DC voltage is applied between the terminals P1 and P2, thereby supplying power between the pair of power supply/signal lines L1 and L2, and detecting a state change based on the detection information from the detection unit 6. Monitor. Such intermittent supply of power to the fire detector continues until the short circuit fault condition is restored.

Next, the operation when the short-circuit failure state is recovered and the normal monitoring state is returned will be explained. When the control unit 7 determines based on the detection information from the detection unit 6 that the current value is a predetermined normal value lower than the short-circuit current value, that is, the normal monitoring state, the control unit 7 prohibits the driving of the power cutoff unit 9 and turns off the signal generation unit. 5 to command information collection.

That is, as shown in FIG. 3, the signal generating section 5 outputs a pulse signal starting from a start signal at every predetermined return time based on a command from the control section 7 which has determined that the normal monitoring state is in effect. Signal generator 5
The power supply unit 4 is activated based on the signal output from the start pulse and sequentially outputs a ringing pulse every predetermined return time in order to restore the initial state and start calling as shown in Fig. 3. . Each fire detector returns data to the receiver 1 within a designated return time in response to a call from the power supply section 4.

(Effects of the invention) As explained above, according to the invention, a plurality of fire detectors are connected between a pair of power supply/signal lines drawn out from the power supply section of the receiver, and the A fire alarm device in which a return current is detected by a current detection unit, information content is determined by a control unit based on detection information from the current detection unit, and a fire alarm is issued when the control unit determines a fire state, A power cutoff unit that outputs a cutoff signal to the receiver based on a control command from the control unit that has determined a short circuit failure state based on detection information from the current detection unit; and switching based on the cutoff signal from the power cutoff unit. Switching means is provided to drive the power supply section intermittently during operation, and in the event of a short-circuit failure, state changes are intermittently monitored, thereby providing protection against failure even if a large current flows due to a temporary cause. At the same time, it is possible to continuously monitor whether the status change, that is, the short-circuit fault condition has been recovered and the normal monitoring condition has returned.

In addition, after the occurrence of a short-circuit fault condition, if it is determined that the short-circuit fault condition has been recovered and the normal monitoring state has returned, normal fire monitoring will be automatically performed, greatly improving the reliability of the fire alarm system. is obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is an overall configuration diagram of the present invention, and FIG. 3 is a signal waveform diagram of each part. 1: Receiver, 2: Fire detector, L1, L2: Power supply signal line, 4: Power supply section, 5: Signal generation section,
6: Detection section, 7: Control section, 8: Alarm section, R1, R
2, R3: Resistor, Q1, Q2, Q3, Q4: Transistor, ZD1, ZD2: Zener diode.

Claims (1)

[Scope of Claim for Utility Model Registration] A plurality of fire detectors are connected between a pair of power supply/signal lines drawn out from the power supply section of the receiver, and the return current from the fire detectors is detected by the current detection section. ,
A fire alarm device in which a control unit determines information content based on detection information from the current detection unit and issues a fire alarm when the control unit determines a fire state, wherein the receiver receives a signal from the current detection unit. a power supply cutoff unit that outputs a cutoff signal based on a control command from the control unit that has determined a short circuit failure state based on detection information; and switching that drives the power supply unit intermittently by a switching operation based on the cutoff signal from the power cutoff unit. A fire alarm device characterized in that it is provided with means.