JPS6017156B2 - fire alarm system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a highly reliable fire alarm system with fewer false alarms.

Fire detectors have conventionally been used that include switching elements such as SCRs that operate when a fire is detected and, once activated, continue to operate unless the supply voltage is reduced below a predetermined value.

When such a fire detector is connected to perform fire monitoring, if the SCR is activated by a momentarily generated yield voltage or a short period of cigarette smoke, it will operate in exactly the same way as when a fire is detected. It has the disadvantage of reporting a conspiracy. Therefore, in order to prevent such accidental alarms, even if a fire detector activates, the alarm is not immediately issued, but the activated fire detector is temporarily reset, and then when the fire detector activates again within a certain period of time. Fire alarm devices configured to issue an alarm have been used in the past.

The present invention provides a fire alarm device having such a configuration,
Even in the case of a large number of lines, a single control circuit is used to perform the same operation as described above, thereby simplifying the apparatus.

An embodiment of the fire alarm system 0 of the present invention will be described in detail below based on the drawings. It consists of a pair of lines m, 1 and one or more fire detectors D connected between the pair of lines m, 1.

5 The receiver Re has a first
a second power source drawn out through a stabilized power supply circuit consisting of a resistor R, a Zener diode ZD, and a transistor Q, and a transistor Q2 and a transistor Q2 that control the output voltage of the stabilized power supply circuit. 0 and resistor R2, capacitor C
2, and two normally open contacts rl, -, . rl, -2 and switching contact rl,
-3 and RL, SCR(S), transistors Q3, Q4, resistors R4 to 8, and a 25th time constant circuit consisting of resistor R3 and capacitor C, and each line has a fire protection circuit. The detection circuit A, -n that detects the operation signal of the sensor D, and the normally open contacts rl, -, ~rln of the detection circuit A and the IJ relay RL correspond to the plurality of capacitors C2 of the control circuit, respectively. and is connected.

It also includes an alarm AR that issues a fire alarm based on the operation of the normally open contacts rl, -2 to rln-2 of the relay RL. The same number of detection circuits A and m are provided as the number of lines extending to each warning area. In the fire alarm system configured as described above, when the fire detector ○ is activated due to the occurrence of a fire, for example, conduction is conducted between the lines 1 and m at a low impedance.

Then, between the power supply E, resistors R5, R6, switching contacts rl, -
3. Line 1, a low impedance circuit of activated fire detector D, and a circuit of line m are formed, and when current flows, transistors Q and Q become conductive, energizing relay RL. The switching contact rl,-3 of the relay RL is switched and connects the line 1 to the junction of resistors R7 and R8. Transistor Q4 immediately turns off, but transistor Q remains conductive for a certain period of time based on the charge on capacitor C, energizing relay RL. Meanwhile, the normally open contacts rl,-, of relay RL are closed, and capacitor C2
Current flows through the series circuit of resistor R2 and transistor Q2, which temporarily becomes conductive, controlling the stabilized power supply circuit and reducing the output voltage to approximately zero. As a result, the supply voltage to the fire detector D falls below a predetermined value and is temporarily restored. The fire detector D is supplied with current from the stabilized power supply circuit during a predetermined time determined by the values of the capacitor C and the resistor R3,
During this time, if fire detector D does not operate again, relay R
L, is deenergized and completely returns to the initial monitoring state.

Further, the normally open contacts rl, -2 of the relay RL, close, but only for a short time, so that the alarm AR cannot be activated.
If fire detector D operates again within this predetermined time,
Between the output terminals of the stabilized power supply, a resistor R7, a sliding contact rl,
-3. A circuit of line 1, fire detector D, and line m is formed, and when current flows, transistor Q becomes conductive, and S
Trigger CR(S).

When the anode and cathode of the SCR(S) become conductive, the relay RL becomes continuously energized. Relay RL
The normally open contact rl, -2 is closed and power is supplied to the alarm AR for a predetermined period of time or longer, so that it operates and a fire is reported by sounding a buzzer or lighting an indicator lamp. The values of capacitor C2 and resistor R2 determine the time required to restore fire detector D, and the values of capacitor C and resistor R3 determine the predetermined time required to monitor for reactivation.

The values of capacitors C, , C2 and resistors R2 and R3 are C2R2
11C and R3, and the monitoring time for reactivation of the fire detector D is set to be much longer than the recovery time. As explained above, the counterfeit fire alarm system of the present invention does not issue an alarm immediately even if the fire detector D is activated, but once the activated fire detector D is restored, the fire alarm system is activated within a certain time. Configure the device to issue an alarm when it operates again to reduce malfunctions and increase reliability.
Restoring fire detector D to 0 is done by controlling the subordinate stabilized power supply circuit, and one control circuit is sufficient for many lines as long as they are supplied by the same stabilized power supply. The device can be simplified, which is very useful in the disaster prevention industry.

The simple explanatory drawing is a wiring diagram showing one embodiment of the fire alarm device of the present invention.

Re...Receiver, m・1...Line, D...
...Fire detector, E...Power supply, A, -n.
...Detection circuit, AR...0...Alarm, RL
．． ...IJ Re, rl,-, ~rln-.・r
l, -2~rln-2... Normally open contact of relay RL, rl, -3... Switching contact of relay RL, R, -
8...Resistance, C.・C2・・・・・・Capacitor,
ZD... Zener diode, Q, -5...
...Transistor, S...SCR.

Claims (1)

[Claims] 1. A fire detector that uses a switching element to short-circuit lines at low impedance when a fire is detected, and continues the short-circuited state until the line voltage drops below a predetermined value; and a first fire detector to which the fire detector is connected. a switching circuit that switches and connects the second power source when the fire detector is activated; and a first circuit that temporarily lowers the second power source to below the predetermined value when the fire detector is activated. a time constant circuit; a second time constant circuit that maintains the switching operation of the switching circuit for a certain period of time and has a time constant longer than the time constant of the first time constant circuit; A fire alarm device comprising: an alarm that issues a fire alarm when activated again within the time constant of a time constant circuit.