JP2994105B2 - Test equipment for disconnection detection function in fire alarm equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test apparatus for testing the function of a receiving unit such as a receiver for detecting a disconnection of a line in a fire alarm system.

[0002]

2. Description of the Related Art In a conventional fire alarm system, a receiver detects that a disconnection has occurred in each line connected to a fire receiver, and tests whether or not the disconnection detection function is normal. The device shown in FIG.

In the conventional apparatus shown in FIG. 2, a reception resistor Rr is connected in series with a fire detector SE connected to each line, and a reception signal detected by the reception resistor Rr is converted into a reference voltage Vref1 for disconnection detection. Is provided, and a test switch SW for disconnecting the common line LC of the line from the fire receiver is provided. When the test switch SW is turned off, the voltage across the receiving resistor Rr becomes lower than the reference voltage Vref1, and if the comparator C1 detects this, the disconnection detection function of the fire receiver RE is recognized to be normal. it can. Note that, instead of the switch SW for disconnecting the common line LC of the line from the fire receiver RE, there is a switch provided with a switch for disconnecting each signal line of the line from the fire receiver RE. In this case, the same operation as above is performed. I do.

[0004]

In the above conventional example, the switch SW is turned off when the disconnection detecting function is tested, and at this time, the power supply to the detector SE connected to the line is cut off. Therefore, there is a problem that even if a fire occurs during the disconnection detection function test, the fire cannot be detected.

Further, in the above-mentioned conventional example, since the state of the sensor SE is cut off at the time of the disconnection detection function test, which is the same state as when the fire recovery operation is performed, the test of the disconnection detection function is completed. Even if the switch SW is turned on, the fire detector SE cannot immediately return to the monitoring state, and only after about 10 seconds have passed since the test of the disconnection detection function was completed (after the switch SW was turned on), Fire detector SE
Returns to the monitoring state. Therefore, in the above-mentioned conventional example, there is a problem that a long time is required until the fire detector returns to the monitoring state after the test of the disconnection detection function is completed.

The present invention can detect a fire during a disconnection detection function test, and immediately after the disconnection detection function test is completed, the fire detector can return to a monitoring state immediately after the fire detector has been disconnected. It is an object of the present invention to provide a test device for a detection function.

[0007]

According to the present invention, a receiving resistor is connected in series with a fire detector, and a received signal detected by the receiving resistor is compared with a reference voltage and a disconnection detecting comparator, whereby a line disconnection is detected. In a fire alarm system having a disconnection detection function for determining the presence / absence of a disconnection, a series circuit including a switching element and a predetermined resistor that is turned on at the time of a line disconnection detection function test is connected in parallel with the reception resistor. It is.

[0008]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. The same members as those shown in the conventional example are denoted by the same reference numerals.

A common line LC and a signal line L are connected to the fire receiver RE1, and a large number of fire detectors SE and one terminating resistor Rt are connected between the common line LC and the signal line L. Have been.

The fire receiver RE1 is provided with a disconnection detection comparator C1 and a fire determination comparator C2. The disconnection detection comparator C1 includes a resistor R
1 and R2, a reference voltage Vref1 for disconnection determination.
And a signal received from the line (common line LC + signal line L).
1, when the voltage across the receiving resistor Rr is lower than the reference voltage Vref1, the disconnection detection comparator C1 outputs "L" indicating the disconnection state, and the disconnection indicator lamp or buzzer (not shown) operates. However, at this time, it is determined that the function of detecting the disconnection of the line by the fire receiver RE1 is normal.

Further, a resistor R0 and a disconnection detection function test switch SW1 are connected in series, and this series circuit is connected in parallel with the reception resistor Rr. Test switch SW
Reference numeral 1 denotes an example of a switching element that is turned on during a line disconnection detection function test. The resistance value of the resistor R0 is a resistance value that enables the fire detector SE to monitor a fire when the switch SW1 is turned on, and also allows the disconnection detection comparator C1 to detect disconnection of the line.

For example, the receiving resistance Rr is 560 Ω, the resistance R0 is 320 Ω, the terminating resistance Rt is 10 kΩ, the reference voltage Vref1 for disconnection detection is 1 V, and the reference voltage Vre for fire determination.
f2 is set to 9 V, and the maximum rating of the fire detector SE is set to 100 mA. Of course, these constants may be changed as needed.

Next, the operation of the above embodiment will be described.

During normal fire monitoring, the switch SW
Keep 1 off. In this case, if the fire detector SE does not detect a fire, a small monitoring current flows through the fire detector SE. If 30 fire detectors SE are connected in parallel, for example, 1. 35 mA flows, and at this time, 2.33 m is applied to the terminating resistor Rt (for example, 10 kΩ).
A current flows, and as a result, a total current of 3.68 mA flows through the reception resistor Rr. In this case, the voltage across the receiving resistor Rr is about 2 V, and since this 2 V is higher than the reference voltage Vref1 of the disconnection detection comparator C1, the disconnection detection comparator C1 indicates that the line is not disconnected. "H" is output.

In the normal fire monitoring, if the fire detector SE does not detect a fire, the received signal becomes 2 V, and this voltage is a reference voltage Vref2 (9 V) for fire determination.
Therefore, when the fire detector SE detects a fire, the received signal becomes about 19 V, and this voltage is a reference value for fire determination. Since the voltage is higher than the voltage Vref2 (9 V), the signal “H” indicating the fire is output to the fire determination comparator C.
2 output and 30-40mA to activated fire detector SE
Flows, and the disconnection detection comparator C1 outputs "H" indicating no disconnection.

Here, the switch SW1 is turned on to test whether or not the function of detecting the disconnection of the line by the fire receiver RE1 is normal. At this time, the fire detector S
Assuming that E has not detected a fire, the received signal, which is the voltage across the receiving resistor Rr, is 0.75 V. This voltage is lower than the reference voltage Vref2 (9 V) for fire determination. The comparator C2 outputs “L” indicating non-fire, the received signal 0.75V becomes lower than the reference voltage Vref1 (1V) for disconnection detection, and the output of the disconnection detection comparator C1 changes from “H” to “H”. The status changes to "L" indicating that the line is disconnected. That is, by turning on the switch SW1, the line is pseudo-disconnected, and if it is determined that the receiver RE1 is disconnected at this time, the disconnection detection function is normal.

On the other hand, during the disconnection detection function test (switch S
Assuming that the fire detector SE detects a fire when the fire detector W1 is turned on, the reception signal, which is the voltage across the reception resistor Rr, is about 19 V, and this voltage is the reference voltage Vref2 ( 9V), the fire determination comparator C2 outputs "H" indicating a fire, and a current of 96 mA flows through the activated fire detector SE.

That is, a fire can be detected even while the disconnection of the line is being detected by turning on the switch SW1. Further, since the current continues to flow through the detector SE while the disconnection of the line is being detected, when the switch SW1 is subsequently turned off, the detector SE immediately returns to the fire monitoring state.

In the above embodiment, the common line LC is 2
In the case of 4V, when the common line LC is negative, when the switch SW1 is turned on, the comparator C
1, The + input potential of C2 is close to 24 V, but the other operations are the same as above. The switch S
W1 is actually an electronic switch using an active element such as a transistor, but may be a manual switch. .

[0020]

According to the present invention, in the test apparatus of the disconnection detection function in the fire alarm system, a fire can be detected at the time of the disconnection detection function test, and immediately after the test of the disconnection detection function is completed, There is an effect that the fire detector can return to the monitoring state.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

FIG. 2 is a circuit diagram of a disconnection detection circuit in a conventional fire receiver.

[Explanation of symbols]

 RE1: fire receiver, C1: disconnection detection comparator, C2: fire determination comparator, Rr: reception resistance, R0: resistance, SW1: disconnection detection function test switch.

Claims (2)

(57) [Claims] 1. A receiving resistor is connected in series with a fire detector, and a received signal detected by the receiving resistor is compared with a reference voltage by a disconnection detecting comparator, whereby
In a fire alarm system that has a disconnection detection function to determine the presence or absence of a line disconnection, a series circuit in which a switching element that turns on during a line disconnection detection function test and a predetermined resistor are connected in series is connected in parallel with the reception resistor. A test device for a disconnection detection function in a fire alarm system, which is characterized in that: 2. The circuit according to claim 1, wherein the resistance value of the predetermined resistor is such that when the switching element is turned on, the fire detector can monitor a fire, and the disconnection detection comparator detects disconnection of the line. A testing device for a disconnection detection function in a fire alarm system, which is a resistance value.