JPS60209897A - Malfunctioning preventor for fire alarm system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a malfunction prevention device for a fire alarm system.

[Background Art 1] Fig. 1 shows a schematic layout diagram of a fire alarm system. Conventionally, in this type of fire alarm system, a fire alarm system is connected via a receiving link-Ry, which is provided in each district, corresponding to the line of receiver A. A double current voltage is applied between the sensor connection line 11 and the common line 1c from the reception fiA, and the image line 1. , a smoke detector 1 connected in parallel to Ic.
a. When either the heat sensor 1b or the transmitter 2 is turned on, an excitation current flows through the receiving relay Ry installed in each area in the receiver A, forming a receiving holding circuit and issuing an alarm output through the other relay contacts. Or, generate drive output from district alarm buzzer output terminal B, and further transmitter 2.
The connection circuit of the connection terminal LA for configuring the energization path for the operation display lamp La inside is turned on.

In the figure, SWo is a recovery switch.

Therefore, for example, even if the smoke detector 1a temporarily operates due to smoke other than fire, there is a problem in that it forms a self-holding circuit and issues an alarm.

[Object of the Invention] The present invention was made in view of the above-mentioned problems, and its purpose is to prevent the receiving relay of the receiver from operating due to a temporary malfunction of the sensor or transmitter. An object of the present invention is to provide a malfunction prevention device for a fire alarm system that can increase the reliability of the system.

[Disclosure 1 of the Invention The present invention will be explained below with reference to an embodiment shown in FIG. In the figure, 3 is a current transformer that constitutes the current detection means of the line current detection circuit section 4. This current transformer 3 has a sensor connection wire passed through, for example, an annular core as a primary winding, and a secondary output. This is input to the line current detection circuit section 4. Line current detection circuit section 4
consists of an amplifier that amplifies changes in the input signal, and a comparator that compares the level of the amplified signal with a preset reference level. In the figure, reference numeral 5 denotes a switching circuit section that turns on when a detection output from the line current detection circuit section 4 is input, and drives the high-sensitivity relay 6. High sensitivity relay 6
A high-sensitivity type is used that operates in a time that is longer than the time it takes for the reception relay RF of reception mA to operate, and when the reception relay Ry is excited, its self-holding circuit is activated by the reception relay Ry. Since the relay contact r0 is made a normally closed contact before forming the relay contact r, it can be reversed to a normally open contact a. Relay contact r. is the common #iIc whose normally closed contact side is connected to the common line connection terminal C.
When the normally closed contact is opened, it cuts off between the common line 1c and the common line connecting terminal C.
The power supply from the receiver A to the smoke detector 1a etc. connected to the common #ife and the common line connection terminal C open is stopped, and the excitation circuit of the receiving relay RF in the receiving mA is cut off. There is. 7 is the first timer circuit section;
When the line current detection circuit section 4 generates the first detection output and the switching circuit section 5 starts to turn on, the timer circuit section 7 starts a time-limited operation from this start, and when a predetermined period of time has elapsed, it starts a time-up output. The first timer circuit section 7 outputs the output to the second timer circuit section 8.
The limited operation time is set to 10 to 20 seconds.
The second timer circuit section 8 starts a time-limited operation when the first timer circuit section 7 times up, and forcibly sets the operation of the switching circuit section 5 to an OFF state during the operation period. Therefore, the current transformer 3, the line current detection circuit section 4, the switching circuit section 5, the first and second timer circuit sections 7.8, and the high sensitivity relay 6 are attached to the existing receiving device A. A malfunction prevention device 9 is configured. The power supply to the malfunction prevention device 9 is common to the power supply #i10 of the receiver A.
Obtained via 1Ife.

Assuming that it is now in the normal state, the sensor connection #ill.

The current flowing through the terminal and the common 1ilc is only the current flowing through the terminator and the leakage current from the sensor, and is very small.

Therefore, the secondary output of the current transformer 3 is close to zero, the detection output of the line current detection circuit section 4 is at "L" level, and the switching circuit section 5 does not operate. Next, when the smoke detector 1a connected to the sensor connection line 1c detects smoke and turns on, the current flowing through both wires 11tlc increases due to short circuit through the impedance inside the smoke detector 1a. The secondary output of the current transformer 3 increases, and this change is immediately amplified and discriminated by the line current detection circuit section 4. If this change exceeds a predetermined level, the line current detection circuit 4 is cleared.
H'' level detection output is generated and turns on the switching circuit section 5. This on operation drives the high-sensitivity relay 6, and the normally closed contact of the relay contact r of the high-sensitivity relay 6 turns off. The line 1c is opened. By opening the line 1c, the excitation current path of the receiving relay Ry1 in the receiving IIA, the sensor connecting line IIs, the smoke detector 1a, and the receiving relay R formed by the common line 1c is cut off. In other words, the time required for the operation of the reception relay Ry (for example, 10+
When the high-sensitivity relay 6 operates earlier than (for example, I 111 sec) the receiving relay Ry does not operate and the receiving relay Ry does not issue a signal at mA.At the same time as the switching circuit section 5 turns on, The timer circuit section 7 of fjSl starts its time-limited operation. During the time-limited operation period of the timer circuit section 7 of fjSl, that is, during the ON operation of the switching circuit section 5, the starting end portion of the common 1i11c is the normally closed contact of the relay contact r. The smoke detector 1a, which had been operating due to the power supply from the receiver (i[8), is now open due to the switch being turned off, and the smoke detector 1a becomes inoperable and returns to normal operation, and the line current no longer flows, so the line current The detection output is no longer generated from the detection circuit section 4, and the switching circuit section 5 is turned off.As a result of this turning off, the high-sensitivity relay Ry returns to its original state and turns on the normally closed contact of its relay contact r. When turned on, the DC voltage from the receiver Δ is applied again between both I/IAI eyes Ic.Then, power is also supplied to the smoke detector 1a, but the smoke detector 1a is Regardless of whether it is a type or an ion type, it takes several seconds to 10 seconds from the time the power is turned on until the smoke detection operation starts, so the smoke detection is detected with a slight delay after the DC voltage is applied. The circuit 1a is turned on again. Due to this turning-on operation, the line current increases, and the circuit current detection circuit section 4 again generates a detection output, turning on the switching circuit section 5 and driving the high-sensitivity relay 6. In this way, the high-sensitivity relay 6 is driven every time the smoke detector 1a is activated,
This prevents the reception relay Ry of the reception mA from operating and self-holding. The operable time of this high-sensitivity relay Ry is defined by the time limit operation time of the first timer circuit section 7. In other words, when the first timer circuit section 7 times up, it sends a time-up output to the second timer circuit section 8,
The second timer circuit section 8 is operated for a limited time from the time-up of the first timer circuit section 7, and a signal is generated to turn off the switching circuit section 5 during the time-limited operation period. Therefore, when the smoke detector 1a operates during the time limit operation period of the second timer circuit section 8, the reception relay Ry of the receiver A is connected to the sensor connection line l, and the smoke detector 1a is connected to the reception relay Ry of the receiver A.
Common 1ife and relay contact r.

An exciting current flows through the normally closed contact S of the receiving relay R.
y operates, its self-holding circuit is formed, and an alarm is issued from the receiving tfiA. By the way, the time limit operation period of the second timer circuit section 8 (for example, 30 to 4
0 sec), unless the smoke detector 1a operates, the receiving relay Ry of the receiving tlA does not operate, and this means that the sensor does not operate during the time limit operation period of the first timer circuit section 7. This indicates that there was a transient B (operation), and false alarms due to malfunction could be prevented. Due to the functions of the line current detection circuit section 4, switching circuit section 5, and high sensitivity relay 6,
The line release operation will be performed in the same manner as described above.

[Effect of the invention 1] The present invention provides the line current detection circuit section depicted as described above,
a switching circuit section, a timer circuit section of fjrJl,
and a second timer circuit section, and when the input switching circuit section drives the switching means, the switching means opens at least the starting end portion of either the sensor connection line or the common line. During the time-limiting operation of the first timer circuit section, the sensing operation of the sensor and transmitter can be canceled, thereby preventing temporary malfunctions.Moreover, the time-limiting operation of the second timer circuit section can cancel the sensing operation of the receiver. Since the operating period of the receiving relay is set, if there is no alarm by the end of this period, the system returns to the original state and prevents false alarms by the line current detection circuit section, switching circuit section, and first timer circuit section. This can improve the reliability of the system, and since it detects the line current, it is possible to use a current transformer that does not require disconnecting the line, and by using a current transformer, multiple It is possible to monitor the line with a single current transformer, and a predetermined operation can be performed no matter which line the sensor is connected to.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional example, and FIG. 2 is a schematic diagram of the present invention, in which 1a is a smoke detector, 1b is a heat sensor, 2 is a transmitter, 3 is a current transformer, and 4 is a schematic diagram of the present invention. Line current detection circuit section, 5 is a switching circuit section, 6 is a high-sensitivity relay, 7 is a first timer circuit section, 8 is a second timer circuit section, ro is a relay saddle point, Ry
is the receiving relay. Agent Patent Attorney Ishi 1) Ai Shichi

Claims (1)

[Claims] 1) Apply DC voltage between the sensor connection line and the common line via the receiving relay in the receiver, and connect a transmitter, heat sensor, or smoke detector between the sensor connection line and the common line. In a fire alarm system in which a heat detector or a smoke detector is connected in parallel and an exciting current is sent to the receiving relay through the sensor when the sensor is turned on, the open current between the sensor connection line and the common line is at a predetermined level. a line current detection circuit section that generates an output when the line current detection circuit section changes to , a switching circuit section that drives a switching means whose operating time is faster than the receiving relay based on the detected high voltage of the line current detection circuit section, and a switching circuit section that starts operation of the switching circuit section. a first timer circuit section that starts a time-limited operation from a time and sets the switching circuit section in an on-operable state until a time-up; and a first timer circuit section that turns off a time-limited operation from a time-up of the first timer circuit section. a second timer circuit section for setting a state, and when the switching circuit section drives the switching means, the switching means opens at least a starting end portion of either the sensor connection line or the common line. A malfunction prevention device for a fire alarm system, characterized by comprising: