Fire Receiver

Abstract

To obtain a fire receiver capable of detecting disconnection even when either one of a first terminator and a second terminator is connected to a sensor line.SOLUTION: A fire receiver to be connected to each one of sensor lines to which fire sensors and a terminator are connected comprises: power sources for applying a power source voltage to the sensor lines; line monitoring sections for respectively monitoring voltages of the sensor lines so as to detect a fire signal from the fire sensors connected to the sensor lines; signal transmission sections for respectively changing line-to-line voltages of the sensor lines so as to transmit a transmission signal to the fire sensors; and control sections for respectively detecting presence / absence of disconnection of the sensor line based on the line-to-line voltage of the sensor line detected by the line monitoring section when the signal transmission section changes the line-to-line voltage in a case where the terminator includes a capacitor, and detecting presence / absence of disconnection of the sensor line based on the line-to-line voltage of the sensor line detected by the line monitoring section in a case where the terminator is a terminal resistance.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fire receiver that is connected to a sensor line to which fire sensors are connected, and that issues a fire alarm for each sensor line. [Background technology]

[0002] In a fire alarm system connected to a P-type fire receiver that issues a fire alarm for each sensor line to which a fire detector is connected, the fire detector that detects a fire notifies the fire receiver of the occurrence of the fire by lowering its own impedance and increasing the current flowing through the sensor line. In such a fire alarm system, a technology has been proposed in which the fire detector changes its own impedance in a pulse-like manner to transmit its own address information to the fire receiver as a transmission signal (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-038647 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the fire receiver also uses a sensor line to transmit a transmission signal to the fire sensor, and the fire receiver and the fire sensor transmit and receive transmission signals in both directions.

[0005] Incidentally, as described in Patent Document 1, a terminator is connected to a sensor line to which a P-type fire receiver is connected in order to detect the presence or absence of a disconnection in the sensor line. There are two types of terminators: one with a capacitor and one with a terminating resistor. Here, a terminator with a capacitor is called a first terminator, and a terminator with a terminating resistor is called a second terminator. Depending on whether a first terminator or a second terminator is used for the sensor line, the method of detecting a disconnection differs. In a sensor line to which a first terminator is connected, the capacitor of the first terminator is always charged, and the capacitor is discharged by periodically lowering the impedance between the sensor lines, and the fire receiver detects the presence or absence of a disconnection by the rate of decrease in the line voltage of the sensor line. In a sensor line to which a second terminator is connected, if no disconnection occurs, a weak current flows in the path of the second terminator in addition to the consumption current of the fire detector in the sensor line, and if a disconnection occurs, the weak current in the path of the second terminator stops flowing in the sensor line. A fire receiver connected to a detector line having a second terminator detects the presence or absence of a break in the detector line by the current flowing through the detector line.

[0006] As described above, the existing fire alarm system has a sensor line connected to a first terminator and a sensor line connected to a second terminator. The sensor line connected to the first or second terminator is laid when the building is constructed and is used for a long time thereafter, but the fire receiver may be renewed as the system ages. When renewing, the type of fire receiver to be used must be different depending on whether the first or second terminator is connected to the laid sensor line. For this reason, it is necessary to manufacture two types of fire receivers, which leads to an increase in manufacturing costs. Alternatively, it is possible to replace the first or second terminator connected to the end of the sensor line with one that matches the disconnection detection method of the fire receiver, but the work of searching for and replacing terminators for all of the multiple sensor lines laid in the building is a heavy burden.

[0007] The present invention has been made in consideration of the above-mentioned situation, and provides a fire receiver that can detect a break in the sensor line regardless of whether the first terminator or the second terminator is connected to the sensor line. [Means for solving the problem]

[0008] The fire receiver of the present invention is a fire receiver connected to a sensor line to which a fire detector and a terminator are connected, and includes a power supply unit that applies a power supply voltage to the sensor line, a line monitoring unit that monitors the voltage of the sensor line and detects a fire signal from the fire detector connected to the sensor line, and a signal transmitting unit that transmits a transmission signal to the fire detector by changing the line voltage of the sensor line, and when the terminator includes a capacitor, detects whether or not the sensor line is disconnected based on the line voltage of the sensor line detected by the line monitoring unit when the signal transmitting unit changes the line voltage, and when the terminator is a termination resistor, When the signal transmission unit does not change the line voltage and a control unit that detects whether or not the sensor line is disconnected based on the line voltage of the sensor line detected by the line monitoring unit. Effect of the Invention

[0009] According to the fire receiver of the present invention, a disconnection can be detected regardless of whether the first terminator or the second terminator is connected to the detector line. [Brief description of the drawings]

[0010] [Figure 1] 1 is an explanatory diagram of a fire alarm system 100 including a fire receiver 1 according to a first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating a transmission signal according to the first embodiment. [Diagram 3] 5 is a timing chart illustrating a disconnection detection function when a first terminator 13A according to the first embodiment is connected. [Figure 4] 10 is a timing chart illustrating a function of determining deterioration of a capacitor of a first terminator according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiment, and various modifications can be made without departing from the spirit of the present invention. The present invention also includes all combinations of possible configurations among the configurations shown in the following embodiment. The device shown in the drawings is an example of the device of the present invention, and the device of the present invention is not limited to the device shown in the drawings. In each drawing, the same reference numerals are used to denote the same or equivalent parts, and this is common throughout the entire specification.

[0012] Embodiment 1 (Configuration of fire alarm system 100) FIG. 1 is an explanatory diagram of a fire alarm system 100 including a fire receiver 1 according to the first embodiment. The fire alarm system 100 is installed in buildings such as hotels, apartment buildings, office buildings, and commercial facilities, and monitors fires and issues an alarm when a fire is detected. The fire alarm system 100 includes a fire receiver 1, a sensor circuit 10 consisting of a common line 11 and a line line 12 drawn from the fire receiver 1, and a fire sensor 20 connected to the sensor circuit 10. The fire sensor 20 notifies the fire receiver 1 of the detection of a fire by lowering the line voltage of the sensor circuit 10 and increasing the current flowing through the sensor circuit 10. The sensor circuit 10 serves both as a power line for supplying power to the fire sensor 20 and as a signal line for transmitting and receiving signals between the fire sensor 20 and the fire receiver 1.

[0013] A first terminator 13A or a second terminator 13B is connected to the end of the sensor line 10. The first terminator 13A is configured by connecting a resistor 133 and a capacitor 132 in series. The resistor 133 is for reducing the charge to the capacitor 132. The second terminator 13B is composed of a terminating resistor 131 and does not include a capacitor 132. As shown in FIG. 1, different types of terminators, namely, the first terminator 13A and the second terminator 13B, can be connected to the fire receiver 1 of this embodiment. Note that, although an example in which the different types of the first terminator 13A and the second terminator 13B are connected to the fire receiver 1 is shown in this embodiment, the fire receiver 1 of this embodiment can also be applied to a sensor line 10 to which only one of the terminators is connected.

[0014] 1 shows an example in which two sensor lines 10 are connected to the fire receiver 1, but the number of sensor lines 10 is not limited to the example shown. Also, in FIG. 1, an example in which two fire sensors 20 are connected to one sensor line 10 is shown, but the number of fire sensors 20 is not limited to the example shown.

[0015] (Configuration of Fire Receiver 1) The fire receiver 1 comprises a main control unit 2, a sub-control unit 3, a power supply unit 4, a receiving resistor 5, a line monitoring unit 6, and a signal transmission unit 7. The same number of sets each consisting of a sub-control unit 3, a power supply unit 4, a receiving resistor 5, a line monitoring unit 6, and a signal transmission unit 7 are provided as the number of sensor lines 10. The main control unit 2 and the sub-control unit 3 form the control unit of the fire receiver 1, with the main control unit 2 controlling the entire fire receiver 1 and the sub-control unit 3 controlling the sensor lines 10.

[0016] The main control unit 2 transmits and receives signals to and from the sub-control unit 3. The main control unit 2 outputs control signals to the sub-control unit 3 to control the sub-control unit 3. The main control unit 2 is composed of dedicated hardware or a processor that executes programs stored in a memory (not shown).

[0017] The sub-controller 3 monitors one sensor line 10, receives output from the line monitoring unit 6 connected to the sensor line 10, and controls the power supply unit 4 and signal transmission unit 7 connected to the sensor line 10. The sub-controller 3 is composed of dedicated hardware or a processor that executes a program stored in a memory (not shown). Note that one sub-controller 3 may be configured to monitor multiple sensor lines 10, or the main control unit 2 may also function as the sub-controller 3 and monitor multiple sensor lines 10.

[0018] The power supply unit 4 converts an AC voltage supplied from a commercial power supply (not shown) into a DC voltage of, for example, 24 V, and supplies the DC voltage to a common line 11 of the sensor circuit 10 .

[0019] The receiving resistor 5 is connected in parallel with the line monitoring unit 6 and the line 12. A current flows through the receiving resistor 5, which is supplied from the power supply unit 4 to the common line 11 and passes through the fire detector 20, the first terminator 13A or the second terminator 13B, and the line 12. When a current flows through the receiving resistor 5, a voltage is generated across the receiving resistor 5. This voltage is called a receiving voltage. In this way, the receiving resistor 5 converts the current into a receiving voltage, and the receiving voltage is input to the line monitoring unit 6.

[0020] The power supply voltage supplied from the power supply unit 4 is divided into the impedance between the common line 11 and the line line 12, which is [line impedance of the sensor circuit 10]:[receiving resistance]. That is, the power supply voltage is divided into the line voltage and the receiving voltage. Therefore, the receiving voltage is the value obtained by subtracting the line voltage from the power supply voltage. Here, the line impedance of the sensor circuit 10 is the composite impedance of the impedance of the fire detector 20 connected to the sensor circuit 10 and the impedance of the first terminator 13A or the second terminator 13B.

[0021] The line monitoring unit 6 judges the state of the sensor line 10. Specifically, by monitoring the voltage of the sensor line 10, it judges whether the state is normal, fire, or disconnection, and outputs the judgment result. The line monitoring unit 6 has a fire threshold for judging whether the state is a fire, and a disconnection threshold for judging whether the state is disconnection when the terminator is the second terminator, and judges the state of the sensor line 10 by comparing the received voltage input via the receiving resistor 5 with the fire threshold and the disconnection threshold. The disconnection threshold is a value smaller than the fire threshold. The line monitoring unit 6 performs a delay operation to confirm the judgment when the sensor line 10 continues to be in the same state for a predetermined delay time, so as not to be affected by momentary voltage changes in the sensor line 10 due to noise.

[0022] The signal transmitting unit 7 is connected to the common line 11 and the line line 12, and transmits a transmission signal to the fire detector 20 by changing the line voltage of the detector line 10. The transmission operation of the transmission signal will be described later.

[0023] (Configuration of fire detector 20) The fire detector 20 is a heat detector, a smoke detector, or a flame detector. When multiple fire detectors 20 are connected to one detector line 10, the fire detectors 20 are connected by a forwarding wiring. When the end of the detector line 10 is a fire detector 20, the first terminator 13A or the second terminator 13B is connected to the fire detector 20 at the end. The fire detector 20 has a built-in contact 21 connected to the detector line 10. The contact of the fire detector 20 is normally open. Therefore, during normal times when the fire detector 20 does not detect a fire, only a weak current flows through the detector line 10. When the fire detector 20 detects a fire, it closes the contact 21 connected to the detector line 10, lowering the line voltage of the detector line 10 and allowing a current larger than normal to flow through the detector line 10. This current larger than normal becomes a fire signal and notifies the fire receiver 1 of the occurrence of a fire.

[0024] In this embodiment, only the contact 21 is shown in the fire detector 20, but the fire detector 20 is composed of a processor and the like. The fire detector 20 normally operates with a very small current consumption, and is therefore in a high impedance state in which the contact 21 in the above description is open. On the other hand, when the fire detector 20 detects a fire, a large current flows, and so the contact 21 in the above description is in a low impedance state in which the contact 21 in the above description is closed. Hereinafter, the operation of the fire detector 20 will be described as the operation of the contact 21.

[0025] (Fire alarm operation of fire receiver 1) When the power is turned on, the fire receiver 1 supplies a power supply voltage to the sensor line 10 by the power supply unit 4. The power supply voltage is, for example, 24 V. The received voltage is input from the receiving resistor 5 to the line monitoring unit 6. The line monitoring unit 6 periodically compares the received voltage with a fire threshold to determine a fire state. When the fire detector 20 detects a fire and closes the contact 21, and the line monitoring unit 6 detects that the line voltage of the sensor line 10 has dropped, a detection signal from the line monitoring unit 6 is input to the sub-controller 3. When the sub-controller 3 receives the detection signal, it notifies the main control unit 2, and the main control unit 2 performs an alarm operation when a fire is detected.

[0026] After the fire detector 20 detects a fire and the fire receiver 1 performs an alarm operation, when a recovery switch (not shown) provided on the fire receiver 1 is operated to input a recovery command, the main control unit 2 disconnects the power supply unit 4 from the detector line 10 and cuts off the power supply to the fire detector 20. This causes the fire detector 20 to recover to its normal state. By recovering to its normal state, the contact 21 of the fire detector 20 opens.

[0027] (Signal transmission by fire detector 1) FIG. 2 is a diagram for explaining a transmission signal according to the first embodiment. FIG. 2 shows a waveform of the line voltage of the sensor line 10. The signal transmission unit 7 of the fire receiver 1 changes the line voltage of the sensor line 10 between a high level and a low level. In FIG. 2, the high level is indicated by H, and the low level is indicated by L. Normally, the line voltage is maintained at a high level. The signal transmission unit 7 changes the line voltage to a low level in a pulsed manner to form a waveform as shown in FIG. 2, and transmits this waveform as a transmission signal to the fire sensor 20. The transmission signal transmitted by the fire receiver 1 is, for example, a request signal that requests the fire sensor 20 to transmit an address or a status. The high level line voltage is, for example, 24 V, and the low level line voltage is, for example, 8.2 V.

[0028] The low-level line voltage transmitted by the signal transmitting unit 7 may be equal to or lower than the voltage at which the line monitoring unit 6 judges a fire to be present when compared with the fire threshold. The signal transmitting unit 7 can also simulate a fire state for testing. Specifically, the low-level line voltage of the signal transmitting unit 7 is set to the same value as the line voltage when the fire detector 20 closes the contact 21. In this way, the same receiving voltage as when the fire detector 20 detects a fire is input to the line monitoring unit 6, and the operation of the fire receiver 1 when a fire occurs can be tested. Thus, according to this embodiment, the signal transmitting unit 7 can be used for both transmitting a transmission signal and for a fire test. Therefore, since there is no need to provide a separate circuit, the increase in manufacturing costs of the fire receiver 1 can be suppressed.

[0029] (Fire detector 1 detects broken wire) Next, the operation of the fire receiver 1 of this embodiment to detect the presence or absence of a disconnection in the sensor line 10 will be described. In the fire receiver 1, whether the first terminator 13A or the second terminator 13B is connected to each of the sensor lines 10 is set in advance by the user. The sub-controller 3 may store the type of terminator of the corresponding sensor line 10, or the main controller 2 may store the types of terminators of all of the sensor lines 10. Alternatively, the type of terminator may be set for each circuit board to which the sensor line 10 is connected.

[0030] The fire receiver 1 of this embodiment is characterized in that it detects the presence or absence of a disconnection in the sensor line 10 by using the above-mentioned signal transmission unit 7. A specific description will be given below.

[0031] Fig. 3 is a timing chart for explaining the disconnection detection function when the first terminator 13A according to the first embodiment is connected. As shown in Fig. 3, the signal transmission unit 7 of the fire control receiver 1 sets the line voltage of the sensor line 10 to a low level in a period T1, and sets the line voltage of the sensor line 10 to a high level in a period T2. The low level period T1 and the high level period T2 are alternately repeated.

[0032] FIG. 3(a) shows the received voltage detected by the line monitoring unit 6 when no break occurs in the sensor line 10 to which the first terminator 13A is connected. Here, the received voltage is a value obtained by subtracting the line voltage from the power supply voltage, and therefore has a waveform that is upside down from the line voltage. When the signal transmitting unit 7 changes the line voltage to a low level, a large current flows through the receiving resistor 5, and the received voltage input to the line monitoring unit 6 rises with a predetermined time constant. Since the capacitor 132 provided in the first terminator 13A is charged, even if the line voltage changes sharply from a high level to a low level, the line voltage gradually drops due to the discharge from the capacitor 132, and the received voltage also rises gradually. Then, when the signal transmitting unit 7 changes the line voltage to a high level, the capacitor 132 of the first terminator 13A is charged, and the received voltage of the line monitoring unit 6 drops and returns to a normal state. The length of the period T1 during which the line voltage is at a low level is set to a period during which the capacitor 132 is not completely discharged. In this way, it is possible to prevent the line voltage from reaching, for example, 8.2V, and to prevent the received voltage from exceeding the fire threshold.

[0033] When no disconnection occurs in the sensor line 10 to which the first terminator 13A is connected, the signal transmission unit 7 alternately switches the line voltage between high and low levels, resulting in the waveform of the received voltage shown in Fig. 3(a). The line monitoring unit 6 does not receive a received voltage higher than the fire threshold. In this state, the sub-control unit 3 determines that no disconnection occurs in the sensor line 10.

[0034] FIG. 3(b) shows the received voltage detected by the line monitoring unit 6 when a break occurs in the sensor line 10 to which the first terminator 13A is connected. When the signal transmitting unit 7 changes the line voltage to a low level, a large amount of current flows through the receiving resistor 5, and the received voltage input to the line monitoring unit 6 rises steeply. When the signal transmitting unit 7 changes the line voltage to a high level, the received voltage of the line monitoring unit 6 drops and returns to a normal state. When a break occurs in the sensor line 10 to which the first terminator 13A is connected, the line monitoring unit 6 detects the steep voltage rise shown in FIG. 3(b) when the signal transmitting unit 7 changes the line voltage to a low level. By comparing the received voltage at this time with the fire threshold, the line monitoring unit 6 outputs a signal indicating a break to the sub-control unit 3.

[0035] In this embodiment, the sub-controller 3 judges whether or not there is a disconnection by comparing the received voltage with the fire threshold, but the fire threshold and the threshold for judging a disconnection may be different. The threshold for judging a disconnection can be appropriately set according to the capacitance of the capacitor 132 of the second terminator, the low level period T1 and the high level period T2 output by the signal transmitter 7.

[0036] Next, detection of a disconnection in the sensor line 10 to which the second terminator 13B is connected will be described. When the second terminator 13B without the capacitor 132 is connected to the sensor line 10, if no disconnection occurs, a weak current flows through the sensor line 10 via the termination resistor 131 of the second terminator 13B. The line monitoring unit 6 detects a received voltage corresponding to this weak current, and if the weak current flows, it determines that no disconnection has occurred. If a disconnection occurs in the sensor line 10, no current flows through the termination resistor 131 of the second terminator 13B, so that the line monitoring unit 6 cannot detect a received voltage corresponding to the weak current. The line monitoring unit 6 detects that a disconnection has occurred in the sensor line 10 by comparing the received voltage with a disconnection threshold, and outputs a signal indicating the disconnection to the sub-control unit 3.

[0037] As described above, in the fire receiver 1 of this embodiment, when the first terminator 13A is connected to the sensor line 10, the presence or absence of a disconnection is detected based on the received voltage detected by the line monitoring unit 6 when the signal transmitting unit 7, which transmits a transmission signal to the fire detector 20, changes the line voltage. Also, when the second terminator 13B is connected to the sensor line 10, the presence or absence of a disconnection in the sensor line 10 is detected based on the received voltage detected by the line monitoring unit 6. Therefore, whether the first terminator 13A including the capacitor 132 is connected to the sensor line 10 or the second terminator 13B including the termination resistor 131 is connected to the sensor line 10, the disconnection can be detected.

[0038] In this embodiment, the signal transmission unit 7 is used to detect a disconnection when the first terminator 13A is connected. Therefore, it is possible to detect the presence or absence of a disconnection in the sensor line 10 to which the first terminator 13A is connected without providing a dedicated circuit for disconnection detection. Therefore, it is possible to suppress an increase in the manufacturing cost of the fire control panel 1.

[0039] (Modification) In the first embodiment, it has been described that which of the first terminator 13A and the second terminator 13B is connected is set in advance by the user for each sensor line 10. As a modified example, a terminator discrimination function that determines which of the first terminator 13A and the second terminator 13B is connected using the signal transmission unit 7 will be described with reference to FIG.

[0040] It is assumed that it is unknown whether the first terminator 13A or the second terminator 13B is connected to each sensor line 10. As shown in FIG. 3, when the signal transmission unit 7 discriminates the terminator, it changes the line voltage of the sensor line 10 from high to low. When the first terminator 13A is connected, the receiving voltage input to the line monitoring unit 6 rises gradually as shown in FIG. 3(a) due to the discharge from the capacitor 132. On the other hand, when the second terminator 13B is connected, since there is no capacitor 132, the receiving voltage input to the line monitoring unit 6 rises steeply as shown in FIG. 3(b).

[0041] In this way, it is possible to detect whether the first terminator 13A or the second terminator 13B is connected to the sensor line 10 based on the received voltage input to the line monitoring unit 6 when the signal transmitting unit 7 reduces the line voltage. Therefore, even if many years have passed since the installation of the sensor line 10 and the user does not know whether the first terminator 13A or the second terminator 13B is connected to the sensor line 10, it is possible to detect a disconnection regardless of the type of terminator.

[0042] Embodiment 2 In this embodiment, a function for determining deterioration of the capacitor 132 of the first terminator 13A will be described. This embodiment is added to the configuration described in embodiment 1. The structure of the fire control panel 1 of this embodiment is the same as that described in FIG.

[0043] Fig. 4 is a timing chart for explaining the deterioration determination function of the capacitor 132 of the first terminator 13A according to the second embodiment. The transmission signal shown in Fig. 4 is the same as that shown in Fig. 3, and shows a waveform generated by changing the line voltage by the signal transmitter 7. Fig. 4(a) shows the received voltage in a state where the capacitor 132 of the first terminator 13A is not deteriorated, and Fig. 4(a1) shows the received voltage in a state where the capacitor 132 of the first terminator 13A is deteriorated.

[0044] When the capacitor 132 is deteriorated, as shown in FIG. 4(a1), the value of the received voltage when the signal transmitter 7 transmits the transmission signal increases over time. Specifically, when the signal transmitter 7 sets the line voltage to a low level, which is the first voltage, during period T1, the received voltage input to the line monitor 6 increases over time. Also, when the signal transmitter 7 sets the line voltage to a high level during period T2, the received voltage input to the line monitor 6 increases over time. The time required to charge the capacitor 132 also becomes longer. In this embodiment, the sub-controller 3 determines the deterioration state of the capacitor 132 of the first terminator 13A by comparing the first detection value, which is the received voltage input to the line monitor 6 when the signal transmitter 7 sets the line voltage to a low level, with a reference value. Alternatively, the sub-controller 3 judges the deterioration state of the capacitor 132 of the first terminator 13A by comparing the received voltage input to the line monitoring unit 6 when the signal transmitting unit 7 switches the line voltage from low level to high level with a reference value. The reference value is stored in advance in the sub-controller 3. When judging the deterioration of the capacitor 132, the pulse width of the transmission signal, i.e., the lengths of the periods T1 and T2, may be made shorter than those during normal transmission of a transmission signal. In this way, the change in the received voltage due to the deterioration of the capacitor 132 becomes noticeable, making it easier to judge the deterioration of the capacitor 132.

[0045] As described above, according to this embodiment, when the first terminator 13A including the capacitor 132 is connected to the sensor line 10, the voltage detected by the line monitoring unit 6 when the signal transmitting unit 7 changes the line voltage is compared with the reference value. Then, the deterioration state of the capacitor 132 is determined based on the comparison result. Therefore, when it is determined that the capacitor 132 is deteriorated, the user is notified, thereby making it possible to prevent continued use of the deteriorated first terminator 13A. Furthermore, according to this embodiment, since it is not necessary to provide a dedicated circuit component for determining deterioration of the capacitor 132 of the first terminator 13A, an increase in the manufacturing cost of the fire control panel 1 can be suppressed. [Explanation of symbols]

[0046] 1 fire receiver, 2 main control unit, 3 sub-control unit, 4 power supply unit, 5 receiving resistor, 6 line monitoring unit, 7 signal transmitting unit, 10 detector line, 11 common line, 12 line line, 13A first terminator, 13B second terminator, 20 fire detector, 21 contact, 100 fire alarm system, 131 termination resistor, 132 capacitor, 133 resistor.

Claims

1. A fire receiver connected to a detector line to which a fire detector and a terminator are connected, A power supply unit that applies a power supply voltage to the sensor line; a line monitoring unit that monitors a voltage of the detector line and detects a fire signal from the fire detector connected to the detector line; a signal transmitting unit that transmits a transmission signal to the fire detector by changing a line voltage of the detector line; When the terminator includes a capacitor, detecting the presence or absence of a disconnection of the sensor line based on the line voltage of the sensor line detected by the line monitoring unit when the signal transmission unit changes the line voltage, and a control unit that detects whether or not the sensor line is disconnected based on the line voltage of the sensor line detected by the line monitoring unit when the signal transmitting unit does not change the line voltage, when the terminator is a termination resistor. Fire receiver.

2. When the terminator includes a capacitor, the control unit determines a deterioration state of the capacitor by comparing a first detection value, which is a voltage of the sensor line detected by the line monitoring unit when the signal transmission unit sets the line voltage to a first voltage, with a reference value; If it is determined that the capacitor is deteriorated, a notification is given.

2. The fire receiver according to claim 1.

Images