JPH0471238B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to alarm devices for fire, gas, theft, etc.

"Prior Art" Conventionally, a fire alarm system includes a receiver (central monitoring device), a power and signal line extending from the receiver, and a plurality of fire detectors or relays connected to this line. There are things that are made up of vessels. If a repeater is used, multiple fire detectors are connected to the repeater via lines.

``Problems to be Solved by the Invention'' Conventional fire alarm devices like this have a serious drawback, especially in large-scale systems, that if the power supply or power/signal line is short-circuited, the entire system will go down. .

"Means for Solving the Problems" The alarm device of the present invention comprises a central monitoring device, a pair of lines drawn out from the central monitoring device and supplied with a predetermined DC power, and connected to the pair of lines. A plurality of terminal devices that are supplied with power and send signals based on the detection of the sensor to the central monitoring device, and are inserted in the pair of lines as appropriate and connected in series to the line when a short circuit condition is detected from the voltage between the lines. In an alarm device consisting of a plurality of disconnection circuits that are disconnected by opening the connected disconnection contacts, the disconnection circuits are connected in series with the line and set to a resistance value that does not affect the power supply. The disconnection circuit connected to the central monitoring device side from the disconnection circuit in contact with the short-circuit point sets a comparison voltage so as not to detect a short circuit based on the voltage drop of the short-circuit current flowing through the resistor and the short-circuit current flowing through the resistor, The present invention is characterized in that a comparator is provided to compare the comparison voltage with the voltage between the pair of lines, and the disconnection contact is driven based on the output of the comparator.

``Function'' Even if a pair of power supply or power/signal lines are short-circuited, the short-circuited section can be disconnected, the remaining system can be made normal, and the monitoring state can be maintained.

"Embodiment" Hereinafter, an embodiment of the alarm device of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing one embodiment of the alarm device of the present invention, which includes a central monitoring device RC, a pair of power supply or power supply/signal lines L and C extending from the central monitoring device RC, This pair of lines L,
Multiple terminal devices SN connected between C and multiple disconnection circuits DX inserted between a pair of lines L and C
It is composed of. The pair of lines L and C may be connected in a loop as shown by dotted lines. Further, the pair of lines L and C are divided into a plurality of sections by a disconnection circuit DX.

To explain the operation of the alarm device configured in this way, the terminal device SN is supplied with power from the central monitoring device RC via a pair of lines L and C, and is in a monitoring state. The terminal device SN sends a detection signal of a fire, gas, etc. sensor or a signal determined based on this detection signal to the central monitoring device RC by superimposing it on the dedicated signal line or the power supply voltage of the pair of lines L and C.
It should be noted that an on/off type fire detector that establishes conduction between the lines when a detection operation is performed is not directly connected between the pair of lines L and C. The central monitoring device RC determines an abnormality based on the signal from the terminal device SN, and also displays an alarm if necessary.

If there is a short circuit somewhere between the pair of lines L and C, power will no longer be supplied to all terminals SN, and the entire system will go down. However, the disconnection circuit DX closest to the shorted section operates and disconnects the line L. Therefore, the remaining terminal equipment
The system consisting of SN continues to maintain the monitoring state normally. Also, if the wires are connected in a loop,
The disconnection circuits DX on both sides of the shorted section are activated and the shorted section is disconnected. Therefore, since power is supplied to the other terminals SN from both ends of the pair of lines L and C, only a part of the system needs to go down.

Next, an embodiment of the disconnection circuit DX is shown and explained in FIG. 2. This disconnection circuit DX has a resistor R
1 to 5, capacitors C1 and 2, and diode D
1, a comparator CP1, a thyristor PT1, and a latching relay RL1 having a disconnection contact RL1.
and a push button switch SW1 for recovery. Terminals 1 and 2 are connected to line L, terminals 3 and 4 are connected to line C, and terminals 1 and 3 are connected to the central monitoring device RC side. The line L is connected to the positive side of the DC power supply, and the line C is connected to the negative side. The resistor R1 has an impedance that does not affect power supply or signal transmission.
Normally, power is supplied from the central monitoring device RC through a pair of lines L and C, and a backflow prevention diode D1
and is charged to capacitor C1 through resistor _R4 . The charge of this capacitor C1 is determined by the comparator
Used as a power source for CP1 and latching relay RL1. If the pair of lines L and C are normal, the resistance R
Since the voltage of the line L supplied through the resistor R5 is higher than the comparison voltage divided by
The output of CP1 is at high level. Thyristor PT1 (programmable union transistor) is therefore not triggered. The contact rl1 of the latching relay RL1 is normally closed, and the terminals 1 and 2 are electrically connected through the resistor R1. If any of the pair of lines L and C is short-circuited, the voltage between the lines L and C at the short-circuit point becomes almost zero. The disconnection circuit DX on the central monitoring device RC side closest to the short-circuit point detects this voltage. That is, at the time of a short circuit, the resistors R1 of each disconnection circuit DX on the central monitoring device RC side are connected in series from the short circuit point, and a short circuit current flows. Therefore, the voltage V _x between terminals 1 and 3 of the disconnection circuit DX in contact with the short-circuit point is determined by the number of connected disconnection circuits DX being m, the power supply voltage being V _c , the line L,
If the resistance of C is ignored, the relationship is V _x ≧1/mV _c .

Therefore, if the divided voltage divided by resistors R2 and R3 is set to a value of about 1/2 mV _c , the disconnection circuit DX closest to the short circuit point on the central monitoring device RC side,
Comparator CP1 of the disconnection circuit DX on the terminal side from this
becomes low level and triggers thyristor PT1. When triggered, thyristor PT1 becomes conductive and causes current to flow through one winding of latching relay RL1 due to the charge in capacitor C1. Latching relay RL1 can be operated to open contact rl1 and disconnect the shorted section. Furthermore, resistance R5
The time constant circuit of the capacitor C2 and the capacitor C2 is designed to prevent the thyristor CP1 from being triggered by a signal in the case of noise or when the pair of lines L and C is used as a power supply and a signal. Also switch
SW1 is operated when the short-circuit fault between the pair of lines L and C is corrected, and the current is applied to the other winding of latching relay RL1 to close the contact rl1 and the status of the pair of lines L and C is changed. It is intended to restore the This disconnection circuit DX is connected to a pair of lines L and C.
Used when the wire is not loop-wired.

Next, FIG. 3 shows another embodiment of the disconnection circuit DX and will be described. This is used when a pair of lines L and C are wired in a loop. In the case of loop wiring, power is supplied from both ends of the pair of lines L and C. Therefore, when a short-circuit fault occurs, the disconnection circuits DX on both sides of the short-circuit point are activated to disconnect the short-circuit section. This disconnection circuit DX consists of resistors R6 to R16 and capacitor C.
3 to 5, diodes D2 to D6, and comparator CP2,
3, thyristor PT2, latching relay RL2 with contact RL2, and recovery switch SW2
It is composed of. Terminals 1 and 2 are connected to line L,
Terminals 3 and 4 are connected to line C, respectively.
The resistor _R6 has an impedance that does not affect power supply or signal transmission. usually,
Power is supplied from the central monitoring device RC via a pair of lines L and C, and the backflow prevention diode D2 and resistor
Capacitor _C3 is charged through _R9 . The charge in capacitor _C3 is used as a power source for comparators CP2 and CP3 and latching relay RL2.
If the comparison voltage V _y divided by resistors R7, 8 and resistors R12, 13 is set to have the relationship 0 < V _y < 1/nV _c (where n is from the short-circuit point to the central monitoring device RC), (The number of connected disconnection circuits DX, V _c is the power supply voltage.) Comparator CP2 of the disconnection circuit DX in contact with the short-circuit section of the pair of lines L and C.
Alternatively, comparator CP3 makes its output low level. The outputs of the comparators CP2 and CP3 of the other isolation circuits DX remain at high level. When either the output of comparator CP2 or comparator CP3 becomes low level, thyristor PT2 is triggered to operate latching relay RL2,
Contact rl2 opens. That is, when a short circuit occurs, the resistor _R6 of the disconnection circuit DX up to the short circuit point is connected in series, and a short circuit current flows, causing a voltage drop. The voltage between the lines LC at the short-circuit point is almost zero, but the voltage between the lines L and LC that sandwich one disconnection circuit DX from the short-circuit point is
The voltage across C is equal to the power supply voltage V _c divided by the number of disconnection circuits DX inserted from the short-circuit point to the central monitoring device RC. Therefore, the disconnection circuit DX connected from the short circuit point to the central monitoring device RC
By setting the comparison voltage V _y as above from the maximum number of circuits, no matter where a short circuit occurs, only the disconnection circuits DX on both sides that are in contact with the short circuit can detect the short circuit and perform the disconnection operation. . Then, power is normally supplied to the terminal devices SN in other sections, and the monitoring state can be maintained.
The time constant circuit of the resistor R10, the capacitor C4, the resistor R11, and the capacitor C5 is designed to prevent the thyristor PT2 from operating due to noise or a signal when the pair of lines L and C is used for power and signal purposes. Diodes D4, 5 connected to the outputs of comparators CP2, 3 are for interference prevention. Also, the switch connected to diodes D3 and D6
When the short-circuit fault between the pair of lines L and C is corrected, SW2 is operated by applying current to the other winding of latching relay RL2, closing contact rl2 and causing the status of the pair of lines L and C. It is intended to restore the

In the disconnection circuit DX shown in FIGS. 2 and 3, the resistor R1 or resistor R6 inserted into the line L
Although a short-circuit section is detected using the voltage drop of the lines L and C, it is also possible to use the resistances of the lines L and C without using the resistors R1 and R6. In this case, the disconnection circuits DX may be inserted at approximately equal intervals when viewed from the line length. And in the case of loop wiring, the second
In the disconnection circuit DX shown in the figure, resistor R1
A circuit configuration in which the circuit is directly connected without using the circuit is sufficient.

If a mechanical indicator is provided that is linked to the operation of latching relays RL1 and 2 of the disconnection circuit DX shown in Figures 2 and 3, it will be possible to easily identify when the disconnection operation has occurred. useful for.

"Effects of the Invention" As explained above, the alarm device of the present invention appropriately inserts a disconnection circuit into a pair of power supply lines or a power supply/signal line, so that even if a short circuit fault occurs in a pair of lines, the alarm device of the present invention can prevent a short circuit from occurring even if a short circuit fault occurs in a pair of lines. Since the circuit is isolated from the circuit, even if a short-circuit fault occurs, the entire system will not go down, improving system reliability. In addition, the power for the disconnection circuit is supplied by a capacitor charged with the voltage of a pair of normal lines, and the use of a latching relay has excellent features such as power savings.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the alarm device of the present invention, FIG. 2 is a circuit diagram showing one embodiment of the disconnection circuit of the same alarm device, and FIG. 3 is another embodiment of the same disconnection circuit. FIG. RC...Central monitoring device, DX...Disconnection circuit, SN
...Terminal, L, C...Line, R1-13...Resistance, C
1 to 5...Capacitor, D1 to 6...Diode,
PT1,2...thyristor, RL1,2...latching relay, SW1,2...switch.

Claims (1)

[Claims] 1. A central monitoring device, a pair of lines drawn out from the central monitoring device and supplied with a predetermined current power, and a signal connected to the pair of lines and supplied with power and based on sensor detection. A plurality of terminal devices that send the signal to the central monitoring device are inserted as appropriate into the pair of lines, and when a short circuit condition is detected from the voltage between the lines, disconnection is made by opening a disconnection contact connected in series to the line. In an alarm device consisting of a plurality of operating disconnection circuits, the disconnection circuit includes a resistor connected in series with the line and set to a resistance value that does not affect the power supply, and a short-circuit current flowing through the resistor. Based on the voltage drop, the disconnection circuit connected to the central monitoring device side from the disconnection circuit in contact with the short-circuit point sets a comparison voltage so as not to detect a short circuit,
An alarm device comprising: a comparator that compares the comparison voltage with the voltage between the pair of lines; and the disconnection contact is driven based on the output of the comparator. 2. The alarm device according to claim 1, wherein the disconnection contact is a latching relay contact. 3. Claim 1, characterized in that the disconnection circuit is provided with a capacitor that charges the voltage between the pair of lines, and when a short circuit occurs, power is supplied to the disconnection circuit by the charge of the capacitor.
Alarm device as described in section. 4. The alarm device according to claim 2, wherein the disconnection circuit is provided with an indicator that mechanically displays the operating state of the latching relay.