JPS5944824B2 - Track monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a track monitoring device that monitors whether a line is normally conducting or is in an abnormal state such as a disconnection or a short-circuit between a pair of lines. It is an object of the present invention to provide a line monitoring device that can efficiently and reliably detect faults in lines connected to load starting devices and abnormalities in starting circuits, especially in disaster prevention systems and the like.

Conventionally, equipment connected to disaster prevention systems, etc. is often used in emergency situations, and is required to operate without fail when a start signal is given.To do this, the lines to which the equipment is connected must be constantly inspected. , it is necessary to monitor the line status.

Conventionally, as a monitoring device for the state of the line, a device for detecting a short circuit or a device for detecting a disconnection of the line has been proposed. An example thereof will be explained using FIGS. 1 to 3. First, FIG. 1 shows an example in which no line monitoring device is installed, and the loads T1 to 7n connected to a pair of lines 11 and 12 are loads having a backflow prevention diode 10.

In this case, if the lines 11 and 12 are disconnected or short-circuited, the devices T1 to Tn, which are loads connected to the lines 11 and 12, do not operate at all. In FIG. 1, 6 is a load starting relay circuit, A is its starting signal, Vcc is a load driving power source, and c and d are terminals interposed between a pair of lines 11 and 12. FIG. 2 shows a conventional example in which a termination diode 9 is connected to the ends of the lines 11 and 12 and a disconnection detection circuit 8 is installed. During monitoring, current constantly flows through the termination diode 9 to the disconnection detection circuit 8. However, if the line, that is, at least one of the pair of lines 11 and 12 is disconnected due to some fault, current will no longer flow to the disconnection detection circuit 8, and the light emitting diode Dx of the circuit 8 will turn off and output a disconnection signal. Become. In the figure, reference numeral 6a denotes a starting relay circuit that is activated by the starting signal A, and also has a function of reversing the polarity between the lines 11 and 12. FIG. 3 shows a conventional example equipped with a short circuit detection circuit 10, in which lines 11, 1
If a normal voltage is applied between 2 (c and d), current will flow to one short circuit detection circuit via resistor R, but if a short circuit occurs on any of the lines, the current will flow between the lines (c and d). between d)
Since the potential difference becomes OV, no current flows to the short circuit detection circuit 10, and the light emitting diode DY of the circuit 10 turns off and outputs a short circuit signal.

In this way, in the past, one of the two detection methods, line short circuit detection and disconnection detection, was adopted as needed, and it was not possible to perform both functions, that is, short circuit detection and disconnection detection, at the same time. It was impossible.

For example, if we consider a circuit that combines the circuit shown in Figure 3 and the circuit shown in Figure 2, a terminating diode 9 is connected to the end of the line to short-circuit the line and detect disconnection. If the termination diode 9 is connected to the circuit, the short circuit detection circuit 10 will be activated immediately, and normal detection operation cannot be expected.

The same applies to the disconnection detection circuit in FIG. 2. For example, if the short circuit detection circuit 10 is connected between the lines 11 and 12 in FIG.
Since the current flows through the wire breakage detection circuit 8 through the wire breakage detection circuit 8, the wire breakage detection circuit 8 is inconveniently determined to be normal.
In addition, even if the line is normal, if the starting relay circuit 6a that supplies the starting power Vcc to the load devices 7, - 7n does not operate normally, it is possible to determine whether there is an abnormality in the line or not.
It is difficult to determine whether there is an abnormality in the starting relay circuit 6a or the starting relay circuit 6a, and it will take a lot of time to repair the line.Also, if the starting relay circuit 6a is abnormal, the starting signal A Even if the input is normal, the contacts of the starting relay do not work properly, or only one contact works and the other contacts do not work, etc. In any case, the load device 7, ~ 7n becomes inoperable, and the reliability of operation in an emergency becomes extremely low.

In order to solve the conventional problems as described above, the present invention provides a line monitoring device that can automatically determine and detect all short circuits, disconnections, and abnormalities in the starting circuit.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings from FIG. 4 onwards.

In the drawings from FIG. 4 onwards, the same components as those in FIGS. 2 and 3 are given the same numbers.

In FIG. 4, Vcc is a power supply externally supplied to operate the load. Reference numeral 6a denotes a starting circuit composed of a relay circuit for starting a load, which inverts the polarity of the power supplied to the lines 11 and 12 in response to a starting signal A, thereby activating the loads 71 to Rn connected to the lines.

Relay contacts Dl and rl2 of this starting circuit 6a are connected to the positions shown in FIG. 4 during normal operation. 2 is the load power supply Vcc
This is a current detection circuit that detects the current flowing into the line from the (G) terminal via the resistors Rl and R3.

Reference numeral 3 denotes a current detection circuit that detects the current flowing from the .

4 detects the current flowing through the resistor R2 and connects the line (c
This is a voltage monitoring circuit that monitors the voltage between md and md.

1 inputs four signals: the output signal A of the current detection circuits 2 and 3, the output signal C of the voltage monitoring circuit 4, and the start signal A, and depending on the state of these signals, the line This is a determination circuit that determines three abnormal states: short circuit, disconnection, and abnormality of the starting circuit 6a, and the determination result is output to output terminal 0.
1 to 03.

Reference numeral 5 denotes a terminator in which a diode D1 and a Zener diode D2 are connected in series in opposite directions. is set to a low value.

Further, as shown in FIG. 5, the voltage monitoring circuit 4 is composed of bridge diodes D4a, d and a current detection circuit 4a, and is capable of detecting current flowing in both directions.

In other words, the circuit outputs an output signal to terminal C regardless of the polarity if there is a certain constant potential between terminals e and f. The operation of the above embodiment will now be explained.

To explain the operation, the load starting power supply Cc is 24V.
1 Zener diode D2's Zener voltage is 10V1 Zener diode D3's Zener voltage is 15V1 Resistor R
1 is 10KΩ, and resistors R2 and R3 are 100KΩ. Under normal conditions, as shown by the solid arrow in FIG. ) terminal to resistors Rl, R3, current detection circuit 2
A current 12 flows toward one terminal of the power supply Vcc through the terminals of the power supply Vcc, and a current 13 flows from the ten terminals of the power supply Vcc through resistors Rl and R2 and the voltage monitoring circuit 4 toward one terminal of the power supply Vcc, and the line voltage ( The voltage across the Zener diode D2 is maintained at 10V.

Therefore, the zener diode D3 has a zener voltage of 1.
Since it is 5V, it becomes non-conductive and no current flows through the current detection circuit 3. Next, as an example, if a short circuit occurs at the line terminals (between cmd), terminal c is at the potential of the power supply Vcc, so naturally terminal d is also at the potential of the power supply Cc, and the above current that normally flows 11, i2, and i3 stop flowing, and the respective detection circuits 2 and 3 and voltage monitoring circuit 4 are all inactive. That is, when the three circuits 2 to 4 and the activation signal A become "0", the determination circuit 1 determines that a short circuit has occurred and outputs a short circuit signal. Next, if a disconnection occurs somewhere between the line terminals Cmd, for example, in one of the loads 7, - 7n or in a part of the lines 11, 12, the current 1, which normally flows through the Zener diode D2, stops flowing, and the potential at terminal d rises.

By doing so, the Zener diode D3 becomes conductive and a current 16 begins to flow through the diode D3. In this disconnected state, the potential of line terminal d is 1
Since it only increases from 0V to 15, the current is 12 (=I4
) and current 13 (=I5) flow as in normal times. As the currents 16, i2, and i3 flow, each of the detection circuits 2, 3 and the voltage monitoring circuit 4 become operational, and their output becomes "1", and the determination circuit 1 receives the respective output signals and "O". A start signal is input and it is determined that the wire is disconnected. Next, when starting the load, the starting signal A is input to the starting circuit 6a, and the contacts R11 and r12 of the starting circuit 6a are switched from the position shown in FIG. 4 to the opposite position.

By switching the contacts, a voltage of normal polarity is applied to the line, and the loads 71 to 7n connected to the line start operating. On the other hand, since the terminal potentials to which the detection circuits 2 and 3 are connected are equal, the detection circuits become inactive.

In the line voltage monitoring circuit 4, current flows in the opposite direction to the normal state through the bridge diode D4 in the current detection circuit 4a and the resistor R2, so the voltage monitoring circuit 4 remains activated. . This state is determined by the determination circuit 1 in the same manner as described above. However, if the starting circuit 6a does not operate normally with the starting signal A and the contacts R11 and r12 do not switch, or only one contact switches, or if the contact becomes open, each state will change. Accordingly, the detection circuits 2 and 3 and the voltage monitoring circuit 4 are activated or inactivated, and the determination circuit 1 determines whether the abnormality is present. The above judgment operations are summarized in the table below.

As explained above, according to the line monitoring device of the present invention, it is possible to distinguish and detect the three conditions of the line short circuit, disconnection, and abnormality of the starting circuit with one device. It is very effective as a line monitoring device that is required to be always operational.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing a line not equipped with a line monitoring device, Figure 2 is a circuit diagram showing a line equipped with a line monitoring device that detects disconnections, and Figure 3 is a circuit diagram showing a line equipped with a line monitoring device that detects short circuits. FIG. 4 is a circuit diagram showing a line equipped with a line monitoring device according to an embodiment of the present invention, and FIG. 5 is a specific circuit diagram of a voltage monitoring circuit of the same device. 1... Judgment circuit, 2, 3... Current detection circuit, 4... Voltage monitoring circuit, 5...
Terminator, 6a...Start circuit (polarity reversal circuit),
11-Tn...Load, Vcc...Power supply, 11, 12...Line, A...Start signal.

Claims (1)

[Claims] 1 Multiple loads including backflow prevention means are connected in parallel 1
A starting circuit that connects a termination diode and a voltage regulator diode in series at the ends of a pair of lines, inverts the polarity between the pair of lines and supplies driving power to the load, and a voltage that monitors the voltage between the lines. a monitoring circuit, a pair of current detection circuits that detect the current flowing from the load starting power supply to the pair of lines, an output signal of the current detection circuit, an output signal of the voltage monitoring circuit, and a starting signal of the starting circuit. A line monitoring device comprising a determination circuit for determining at least three conditions: disconnection, short circuit, and abnormality of the polarity reversal circuit between the lines.