JPS5825509Y2 - Fire alarm disconnection detection device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a disconnection detection device for a fire alarm.

Generally, in a fire alarm system, a sensor is connected to a signal/feeder line drawn out from a receiver, and when the sensor detects a fire and becomes low impedance, the current flowing through the line is activated. , the receiver is configured to operate a transistor, etc., and to notify a fire by operating the transistor.

Conventionally, as a wire breakage detection device for detecting the above-mentioned wire breakage, one shown in FIG. 1 is known.

In FIG. 1, 1 is a receiver, and a plurality of sensors 3a, 3b are connected to signal/feeder lines 2a, 2b drawn out from the receiver, and the lines 2a, 2b are A terminator 4 that intermittently short-circuits the line is connected to the end via a resistor.

The receiver 1 includes a power source 5, a current detection resistor R1 of a line inserted in series with the line 2a, a transistor Q1 that is turned on by the voltage across the resistor, a capacitor C1 that is charged when the transistor is turned on. When the charging voltage of the capacitor exceeds a predetermined value, the Zener diode ZD
The thyristor 5cR1 is turned on when a voltage is applied to its gate via the thyristor 5cR1, and the alarm indicator lamp PL1 is supplied with current when the thyristor 5cR1 is turned on.

In addition, the receiver 1 includes a transistor Q2 that is turned on by the charging voltage of the capacitor C1, and resistors R2 and R.
A voltage divided by 3 is applied to the gate and resistor R4
A programmable unijunction transistor PUT1 comprising an oscillator and an anode to which a charging voltage of a capacitor C2 charged via the PU is applied;
T, of the cathode resistance R5! The transistor Q2 is equipped with a thyristor 5cR2 that is turned on when the thyristor is turned on, and a disconnection indicator light PL2 that is turned on when the thyristor is turned on.
When the capacitor c2 is turned on, the capacitor c2 is discharged.

In such a fire alarm disconnection detection device, for example, when the detector 3a is activated, the lines 2a and 2b are short-circuited, and due to the short circuit, a large current flows through the lines 2a and 2bK:, and a voltage is generated across the resistor R1. As a result, transistor Q1 is turned on.

As a result of this turning on, a large charging current flows through the capacitor C□ and the voltage rises, and the thyristor 5CR1 is turned on via the Zener diode ZD, and this turning on causes the alarm indicator lamp PL□ to light up.

At this time, the transistor Q2 is also turned on and the capacitor C2 is discharged, so the thyristor 5CR2 is not turned on.

During monitoring, the transistor Q1 is intermittently turned on due to the current flowing through the terminator 4, but during this on period, the voltage across the capacitor C1 is the same as that of the Zener diode.
Although it does not reach the voltage that turns on ZD, the transistor Q
2 is turned on intermittently and capacitor C2 is discharged, so PUT1//i does not turn on.

When the lines 2a and 2b are disconnected, no current flows through the resistor R□, so the transistor Q□ remains off, and the voltage charged via the resistor R4 of the capacitor C2 is transferred to the resistor R2.
, becomes higher than the divided voltage of R3, P U T 1 is turned on and a voltage is generated in resistor R5, and thyristor 5CR2
is turned on and the disconnection indicator light PL2 is lit.

In such a conventional device, when a large number of low impedance smoke detectors are connected to the lines 2a and 2b, the transistor Q1 must be set to conduct with a large current to prevent malfunction. Therefore, it is necessary to flow a large current through the terminator 4 in order to make the transistor Q1 conductive intermittently during monitoring.

This has the disadvantage that when a large number of lines are provided, the capacity of the electric wire 5 becomes insufficient, making it impossible to detect disconnection, and increasing power consumption.

The present invention eliminates the above-mentioned drawbacks, and reduces power consumption by separating the alarm detection means and disconnection detection means, so that even if a large number of lines are installed, the power supply capacity will not be insufficient, and the system can be easily installed. An object of the present invention is to provide a wire breakage detection device that can reliably detect a wire breakage.

An embodiment of the present invention will be described in detail below with reference to FIG.

In FIG. 2, the same reference numerals as in FIG. 1 indicate the same effect.

The terminator 4 has a capacitor C3 whose gate is charged with a voltage divided by the resistors R6 and R7 of the lines 2a and 2b, and which is charged by the current from the lines 2a and 2b supplied via the resistor R3. The oscillator is composed of a programmable unijunction transistor PUT2 having an anode to which a charging voltage is applied, and a transistor Q3, etc., whose base is supplied with current via the resistor R9 of the PUT2, which is the output of the oscillator. The transistor Q3 is intermittently turned on in response to the oscillation output of
are intermittently short-circuited as in the case of FIG.

6 is an alarm detection circuit, which uses a sensor 3a etc. to detect the alarm on the line 2.
When a s2b is short-circuited, the resistor R1
Capacitor C1 is charged via □, and when this charging voltage reaches a predetermined value, alarm indicator light PL1 is lit.

Reference numeral 7 denotes a disconnection detection circuit that detects disconnection of the lines 2a and 2b based on the presence or absence of an intermittent line monitoring current that flows when the terminator 4 is activated. A capacitor C4 is charged through the capacitor C4 and discharged through the resistor R13, the diode D1, and the light emitting diode D2 at the time of the short circuit based on the intermittent operation of the terminator 4, and the capacitor C4 is connected in series with the capacitor as described above. In addition, a light emitting device is connected in parallel with the high resistance R12 and includes the light emitting diode D2, etc., which emits light due to the intermittent discharge current of the capacitor C4, and a phototransistor Q4, etc., which receives the light emitted from the light emitting device. a photoreceiver, and the programmable unijunction transistor P U T 1 z capacitor C controlled by the photoreceiver.
2. Switching means consisting of resistors R2 to R5, and thyristor S'CR2 operated by the switching means
It consists of a wire breakage indicating means consisting of a wire breakage indicator light PL2 and the like.

In such a fire alarm disconnection detection device, the sensor 3a
The alarm indicator light PL is lit by the following actions.
The oscillator composed of PUTl is activated due to a disconnection of the lines 2a and 2b, and the disconnection indicator light PL2 is turned on, as in the case of Fig. 1. Differently, due to the discharge of capacitor C4,
The light emitting diode D2 emits light, and the light emission turns on the phototransistor l'Q4, which discharges the capacitor C2 and suppresses the oscillation of the oscillator made of PUT1.

Above resistor R4sR8R12 and capacitor C2s C3s
The time constant consisting of C4 is R4・C2〉R3・C3〉R1
By selecting 2.C4, the oscillation of the oscillator made of PUT□ can be reliably suppressed during the above-mentioned monitoring.

The present invention is as described above, and the capacitor C4 is charged by the current flowing through the high resistance R12, and when the transistor Q3 of the terminator 4 is on, the capacitor C4 is discharged. Even if the power supply 5 of receiver 1 increases,
/I'i, a device with a small capacity can be used, and power consumption can also be reduced.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional example, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. 1: Receiver, 2a, 2b: Line, 3a, 3b: Sensor, 4: Terminal, 6: Alarm detection circuit, 7: Disconnection detection circuit, R1゜: High resistance, C4: Capacitor, D2: Light emitter Q4: A phototransistor that serves as a light receiver; Ph3: A disconnection indicator that serves as a disconnection indicator.

Claims (1)

[Scope of utility model registration request] A line to which a plurality of fire detectors are connected, a terminator installed at the end of the line to intermittently short-circuit the line, and an alarm that is sent to a receiver to detect the alarm current of the fire detector. and a disconnection detection circuit for detecting a disconnection of the line based on the presence or absence of an intermittent line monitoring current when the terminator is activated, the disconnection detection circuit of the fire alarm is pressed. is a capacitor that is charged through a high resistance and discharged based on the intermittent operation of the terminator, and a capacitor that is connected in series with the capacitor and in parallel with the high resistance, and that is connected in series with the capacitor and in parallel with the high resistance, and which is connected in series with the capacitor and discharged based on the intermittent operation of the terminator. a light emitter that emits light by electric current; a light receiver that receives the light emitted from the light emitter;
A disconnection detection device for a fire alarm, comprising a switching means controlled by the light receiver, and a disconnection display means operated by the switching means.