JP2002291071A - Central supervisory device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a central supervisory device that can correctly detect a return signal without malfunction of short-circuit detection even when the device is connected to many terminals requiring much current. SOLUTION: The central supervisory device transmits a voltage signal to a terminal and also supplies power to the terminal and receives a return signal from the terminal by a current of the power supply flowing through the terminal. The central supervisory device changes each comparison reference value for a comparator 13 to detect the return signal and for a comparator 14 to detect a short-circuit signal according to the increase in the current supplied to the terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a central monitoring device having a configuration in which terminals for opening and closing the power supply of electrical equipment are connected via a multiplex transmission line.

[0002]

2. Description of the Related Art FIG. 3 shows a configuration of a monitoring system having a central monitoring device. In a building such as a building, the central monitoring device 1 is connected via a multiplex transmission line 2 to a terminal 3 for opening and closing a power supply of electric equipment such as a power motor 4 and a lighting fixture 5.

FIG. 4 shows a transmission section of the central monitoring device 1. The transmission section connects the transistors Q1, Q2, Q3, Q4 and the power supply circuit 102 to the multiplex transmission signal generation circuit 101 to generate a multiplex transmission signal.

FIG. 5 shows an example of a multiplex transmission signal.
By alternately switching Q4, Q2, and Q3, a pulse signal of ± 24 V can be generated, and the data is transmitted to the terminal device 3 with the pulse width of 100 μsec as 0 value and the pulse width of 200 μsec as 1 value. I have. In addition, terminal 3
Is used as an internal power supply of the terminal device 3 by performing full-wave rectification of a pulse signal having a voltage of ± 24 V. The return current from the terminal 3 flows through the resistor R1. The current flowing through the resistor R1 is detected by the comparator 103 as a return signal.

FIG. 6A shows a current flowing through the resistor R1 in a normal state. The current flowing when the transmission line 2 is short-circuited or when the terminal 3 fails in the short-circuit mode is determined by the comparator 1
04 is detected. FIG. 6B shows the resistance R when the transmission line is short-circuited.
1 shows the current flowing through the circuit.

[0006]

The terminal 3 is connected to the transmission line 2.
From the power supply necessary for driving the circuit operation of the terminal device 3 and the built-in relay. When a large number of terminals 3 are used for one channel of transmission, the power for driving the relay is supplied from the transmission line 2, so that the current in the transmission line 2 increases and the short-circuit detection circuit operates. FIG. 6C shows a current flowing through the resistor R1 when the terminal device is driven.

That is, when the relay drive current is added to the supply current to the terminal device 3 and the return current is added thereto, the current flowing through the resistor R1 reaches the short-circuit current threshold value. As a result, the transmission line 2 and the terminal 3 are normal, but the transmission unit determines that the transmission is short-circuited.

The present invention has been made in view of such circumstances, and even when a large number of terminals consuming a large amount of current are connected, a correct return signal is output without causing a malfunction in short-circuit detection. The purpose is to provide a central monitoring device that can be detected.

[0009]

In order to achieve the above object, a central monitoring device according to the first aspect of the present invention sends a signal by voltage to a terminal, supplies power at the same time, and supplies current to the terminal. Receiving the return signal from the terminal, and varying the comparison reference values of the comparator for detecting the return signal and the comparator for detecting the short-circuit signal in accordance with an increase in the current supplied to the terminal. It is characterized by.

According to a second aspect of the present invention, the central monitoring device sends a signal to the terminal at a voltage and supplies power at the same time, receives a return signal from the terminal by the current of the power supply, and detects the return signal. The comparison reference value of the comparator is varied as the current supplied to the terminal increases.

According to a third aspect of the present invention, the central monitoring device sends a signal to the terminal device with a voltage and simultaneously supplies power, and receives a return signal from the terminal device by the current of the power source. The comparison reference value of the comparator is varied as the current supplied to the terminal increases.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a central monitoring device 1
FIG. 3 is a diagram illustrating an example of a configuration of a transmission unit. The transmission unit supplies the multiplex transmission signal generation circuit 11 with the transistors Q1, Q2, Q
3, Q4 and the power supply circuit 12 to create a multiplex transmission signal.

The central monitoring device 1 sends a signal as a voltage to the terminal device 3 and supplies power at the same time. The central monitoring device 1 receives a return signal from the terminal device 3 by the current of the power source, and a comparator 13 for detecting the return signal. And the comparison reference value of each of the comparators 14 for detecting the short-circuit signal is changed in accordance with an increase in the current supplied to the terminal 3.

Here, a resistor R2 and a resistor R3 are connected in parallel with the resistor R1. The connection point between the resistors R2 and R3 is connected to the input of the buffer 15. The output of the buffer 15 is connected to the anode of the Zener diode ZD1.

When the return current of the transmission line 2 increases, the resistance R
1 and the current flowing through the resistors R2 and R3 increase. Resistance R
3 is received by the buffer 15. Buffer 1
Reference numeral 5 denotes an amplifier having an amplification factor of 1. The output of the buffer 15 generates a voltage equivalent to that of the input. The cathode voltage of the Zener diode ZD1 is a voltage obtained by adding the breakdown voltage of the Zener diode ZD1 and the output voltage of the buffer 15. As the return current increases, the comparison reference values of the two comparators 13 and 14 change.

FIG. 2 shows the current waveform at that time. (A)
As shown in (2), in the normal state, only the return signal of the current flowing through the resistor R1 exceeds the return current threshold, and the comparator 13 outputs the return signal. When the transmission line is short-circuited, the current flowing through the resistor R1 exceeds the short-circuit current threshold as shown in (b), and the comparator 14 outputs a short-circuit signal.

One address of the transmission line 2 has a large number of terminals 3
Is connected, the relay of the terminal device 3 is driven, and the transmission line 2
(C), the two threshold values fluctuate according to the current of the transmission line 2 as shown in (c), so that the comparator 3 can correctly detect the return current and output the return signal. .

Thus, in the multiplex transmission of the central monitoring device 1, when a large number of terminals 3 having a built-in relay are connected without increasing the number of addresses, erroneous short-circuit detection of the transmission line 2 during driving of the relay is eliminated.

[0019]

As can be understood from the above description, in the central monitoring device according to the first aspect of the present invention, each of the comparator for detecting the return signal and the comparator for detecting the short-circuit signal is provided. Since the comparison reference value is fluctuated in accordance with an increase in the current supplied to the terminal device, even when a large number of terminal devices consuming a large amount of current are connected and the relay built in the terminal device is driven, the malfunction of the short-circuit detection is prevented. Without this, the reply signal can be correctly detected.

According to the second aspect of the present invention, the central monitoring apparatus varies the reference value of the comparator for detecting the return signal in accordance with an increase in the current supplied to the terminal. Are connected, and even when a relay built in the terminal device is driven, a reply signal can be correctly detected.

According to the third aspect of the present invention, the central monitoring device varies the reference value of the comparator for detecting the short-circuit signal in accordance with an increase in the current supplied to the terminal device. Are connected, and even if the relay built in the terminal device is driven, the short-circuit detection does not malfunction.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a configuration of a transmission unit of a central monitoring device of the present invention.

FIG. 2 is a diagram showing an example of a current waveform in the central monitoring device of the present invention.

FIG. 3 is a diagram illustrating an example of a configuration of a monitoring system.

FIG. 4 is a diagram illustrating an example of a configuration of a transmission unit of a conventional central monitoring device.

FIG. 5 is a diagram illustrating an example of a multiplex transmission signal.

FIG. 6 is a diagram showing an example of a current waveform in a conventional central monitoring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Central monitoring apparatus 2 Multiple transmission line 3 Terminal equipment 13 and 14 Comparator

Claims (3)

[Claims] 1. A central monitoring device in which a terminal for opening and closing the power supply of an electric facility is connected via a multiplex transmission line.
The current of the power supply receives the return signal from the terminal. The comparator for detecting the return signal and the comparator for detecting the short-circuit signal use the respective comparison reference values to increase the current supplied to the terminal. Therefore, a central monitoring device characterized by varying. 2. A central monitoring device in which a terminal for opening and closing the power supply of an electric facility is connected via a multiplex transmission line.
A central monitoring device which receives a return signal from a terminal by the current of the power supply, and varies a comparison reference value of a comparator for detecting the return signal with an increase in current supplied to the terminal. 3. A central monitoring device in which a terminal for opening and closing a power supply of an electric facility is connected via a multiplex transmission line.
A central monitoring device, which receives a return signal from a terminal by the current of the power supply, and changes a comparison reference value of a comparator for detecting a short-circuit signal in accordance with an increase in current supplied to the terminal.