JPS6158422A - Monitor signal transmitter - 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] Regarding the method of transmitting the number.

(Prior art) In general, in a transformer that transforms high-voltage electricity into low-voltage electricity, the insulation condition of the secondary low-voltage circuit is monitored, and in the event of an abnormality in the insulation resistance value, this can be quickly detected and immediate countermeasures taken. Various monitoring devices will be installed at required locations to ensure a stable and constant supply of power.

Such a method of monitoring the condition of the electrical circuit generally involves the second
A detector is installed on the ground wire to measure commercial power components or iE path conditions that leak through impedance (insulation resistance or capacitance components, etc.) existing between the low-voltage line and the ground. Generally, this is done by detecting a component of a signal of a frequency different from the frequency applied to the entire electric circuit that leaks through the impedance.

Therefore, these monitoring devices are naturally installed near the transformer.

However, since high constant voltage transmission lines enter the power receiving room where the transformer is installed,9 people are usually called to a place where they are not permanently stationed. It is necessary to transmit the information to an office or control center where a person is permanently stationed.

Conventionally, the method for transmitting this monitoring signal has been to install a new monitoring signal transmission line between these monitoring devices and the office.

It took a lot of time and money to install all the transmission lines in existing buildings. In order to reduce this burden, a high-frequency carrier signal modulated with the signal to be transmitted is superimposed on the existing power wiring for electric lights between the power receiving room and offices, etc., and this high-frequency signal is received at the Imperial Palace, etc. However, there was a method (power line transmission method) in which the necessary monitoring signals were transmitted by demodulating them.

Also, as another method, transformer 2 can be used instead of the above-mentioned power line.
Grounding S for second-class grounding work for low-voltage power lines, i.e., power transmission
All low frequency signals corresponding to υ noise signals etc. to be transmitted to the electric line via There has been a method of detecting the low frequency signal voltage or 'ε current of , and identifying the presence or absence of a notification signal or its type.

(Problems to be Solved by the Invention) However, all of the conventional alarm signal transmission methods as described above have various drawbacks.

In other words, in the former electric light line transportation method, since power wiring for electric lights is used, signal transmission may not be carried out sufficiently due to changes in the negative load of the lamp, and the length of the electric power wiring for electric lights, load, etc. are all constant. However, the latter method using a power transmission line has the disadvantage that it cannot be put to practical use unless it is constrained by the following conditions.

If a ground fault or similar accident occurs in these electrical circuits, the voltage at the grounding point of the Type 3 grounding work will rise to the electrical circuit voltage, causing the reception circuit to become saturated and the reception of the transmitted signal to be interrupted. This had the disadvantage that even if a monitoring signal was being transmitted, it could not be reproduced by the receiving section due to an abnormal drop in the impedance between the electrical line and the ground.

(Means and effects for solving the problem) The present invention has been made to solve the problems of the conventional method as described above. It detects and forcibly outputs an alarm signal to the receiving output, making it possible to detect any abnormality in the electric circuit with certainty from the receiving output.

In addition, when applying the transmission signal to the grounding wire of Type 2 construction,
By using a low-frequency signal with low internal resistance, attenuation is small, and even in long-distance electrical circuits, reliable positioning is provided without being affected by the load.

(Example) The present invention will be described in detail below based on an illustrated example.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the same figure, T indicates a transformer that transforms high-voltage electricity into low-voltage electricity. Show each. The electric line 2 is subjected to type 2 grounding work using a grounding wire 4 at the transformer.

In this embodiment, the present invention is applied to such an electric line, and an alarm signal generated by a monitoring device 5 attached to an insulation resistance measuring device etc. installed near the transformer T is transmitted to a small electric line on the extension of the electric line. This shows a case where the signal is transmitted to a coarse signal receiving device 6 installed in an office or the like.

First, the output of the insulation monitoring device 5 and the modulation device 7 are connected through the terminal 8, and the modulation section 7 modulates the carrier wave low frequency signal with the monitoring signal generated by the insulation monitoring device 5. After conversion, etc., it is injected into a transformer 9 coupled to the ground line 4, and applied to the electric line 2 via the ground line.

On the other hand, in the alarm signal receiving device 6, the ground phase line 2
The above-mentioned modulated carrier low frequency signal induced between this and the grounding line 11, which has undergone type 3 grounding work on the ground E3, is derived to the demodulation circuit 12 via the connection line 10 provided at the ground E3. At this time, insert a capacitor into the connecting wire 10 provided between the electrical circuit 2 and the demodulation circuit 12, so that the insulation resistance value will not be affected when measuring the insulation resistance with a DC voltage using a megger or the like. Keep it.

By making the input terminal of this demodulation circuit have a sufficiently high impedance with respect to the load connected to the electric line, the negative influence of the alarm signal receiving device 6 on the commercial power of the electric line
'C should be prevented.

The modulated carrier signal derived in this way is demodulated after removing the commercial power frequency component and its harmonic components inside the receiving device 6, detects the transmitted alarm signal, and identifies all types of the signal. do.

Further, a 13-karat gold ground fault detection circuit is connected in parallel with the demodulation circuit between the ground phase circuit 2 and the third type ground wire 11,
It is configured to detect a commercial power supply voltage that rises above a certain level due to a ground fault in the electric line and to notify that fact, or the output of the receiver 6 is configured to generate an alarm signal regardless of the result of detection of the modulated carrier signal. Connect to control the received state.

It goes without saying that the input power to the ground fault detection circuit 13 at this time is also configured to have a high impedance with respect to the commercial power supply.

It would also be effective to take into account that the demodulation circuit outputs a 0 signal in the safe direction so as to generate an alarm when the transmission signal cannot be received.

As is clear from the above explanation, if a device configured in this manner is used, the power wiring will be grounded all around the disconnection monitoring device, and the noise signal will be transmitted to the office connected to the same transformer far away due to the extension of the electrical path. can be reliably transmitted to the receiving end.

It is clear that the above embodiments can also be used in the case of a single-phase three-wire system.

Furthermore, various configurations of these devices can be considered in addition to the above-mentioned embodiments.2For example, there may be a device in which the insulation resistance measurement function of the electrical circuit and the above-mentioned bulletin signal transmission function are combined in the same device, or It is clear that any modulation method may be used when superimposing the signal on the gold carrier wave.

(Effects of the Invention) Since the present invention is configured and functions as described above, even in the event of an accident such as a ground fault in an electric line, the alarm signal will not be interrupted and the alarm signal will be accurately transmitted. It has an extremely large effect on this.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. 1.3......Ungrounded electrical circuit, 2...
・・・・・・Grounding circuit, 4 and 11・・・・・・−
・Grounding wire. 5...Insulation resistance monitoring device, 6...
......Receiving device, 7...Modulator, 9...Injection transformer, 1
0......Connection line. 12... Demodulation circuit, 13...
...Ground fault detection circuit.

Claims (1)

[Claims] A low-frequency transmission signal modulated by an alarm signal, etc. to be transmitted obtained from an insulation monitoring device, etc. is transmitted to the low-voltage secondary circuit via the grounding wire of the second-class grounding work of a transformer that transforms high-voltage electricity to low-voltage electricity. , and detecting and demodulating the low frequency voltage induced between the earth and the grounding line of the low voltage line on which the second type grounding work has been carried out on the extension of the line. A supervisory signal transmission device characterized in that it outputs a signal such as a transmitted alarm, and also forcibly outputs an alarm signal when the commercial frequency voltage between the grounding cable and the ground exceeds a predetermined value. .