JPS5852418B2 - Enkakuondo Kanshi System - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a remote temperature monitoring system for remotely monitoring temperature abnormalities at temperature monitoring points in an electrical system.

2. Description of the Related Art Electrical systems, such as power transmission and distribution systems and power distribution systems in factories, need to be periodically inspected to prevent accidents from occurring.

This inspection is becoming increasingly important, especially in today's large-scale electrical systems.

However, in such large-scale electrical systems, it is extremely dangerous for workers to directly approach the inspection points, and it is necessary to stop the operation of the electrical system even temporarily for inspection. This is generally not allowed, and safety cannot be ensured with conventional periodic inspections, so it is necessary to prepare a system to constantly monitor the status of the electrical system.

In order to meet such demands, the present invention aims to provide a remote temperature monitoring system that can constantly and remotely monitor temperature abnormalities in various parts of the electrical system that are most closely related to abnormalities in the electrical system and are likely to develop into accidents. .

In particular, the present invention takes into consideration application to electrical systems such as high-voltage power transmission systems where temperature monitoring points cover a wide range of areas and use high voltages, and the present invention provides a transmitter for detecting the temperature at a temperature monitoring point in an electrical system, and a temperature information The present invention aims to provide a remote temperature monitoring system for an electrical system, which is configured to connect a transmitter with a receiver that displays and notifies the temperature by radio waves, and to supply operating power for the transmitter from the electrical system to be monitored. .

Hereinafter, the present invention will be specifically explained based on Examples.

FIG. 1 shows the overall configuration of an embodiment of the remote temperature monitoring system according to the present invention, in which 11 to 13 are electrical systems for temperature monitoring, 21 to 2n are transmitting devices, 31 to 3B are receiving devices, and 4
is the central monitoring device.

The transmitting devices 21 to 2n are installed close to or in close contact with temperature monitoring points of the electrical systems 11 to 13, such as heat generating parts such as circuit breakers and transformers, or connection points of power transmission lines, and transmit temperature information radio waves at the corresponding temperature monitoring points. 51 to 5n are transmitted.

The receiving devices 3□~3n receive the above-mentioned corresponding temperature information radio waves 5□~
5n, and displays temperature information indicating whether the temperature monitoring points of the electrical systems 1 to 13 are normal or abnormal, and at the same time sends an alarm signal and other necessary signals to the central monitoring device 4 through the cable 6 or the like.

This central monitoring device 4 receives alarm signals and the like sent from each of the receiving devices 3 and 33 and centrally displays the presence or absence of an abnormality in the electrical systems 1 and 13, and also centrally displays the presence or absence of an abnormality in the electrical systems 1 and 13. Monitor the operations of □ to 33.

Each of the above-mentioned transmitting devices 21 to 2n is equipped with a temperature sensing element whose characteristics change in accordance with the temperature at the temperature monitoring point of the electrical system 1 to 13, and the temperature information radio wave 5 is transmitted based on the change in the characteristics of the temperature sensing element.
1 to 5n, and the operating power is supplied from the corresponding electrical systems 1□ to 13.

A specific example of the configuration of the transmitting devices 2□ to 2n will be explained with reference to FIG.

In the figure, a transmitting device 2 includes a carrier wave oscillating section 7 and a temperature-
It is generally composed of a frequency conversion section 8 and a power supply section 9.

The temperature-frequency converter 8 is programmable.

Unijunction, transistor (hereinafter abbreviated as PUT).

) This is a relaxation oscillation circuit using Q2. The anode of PUTQ2 is connected to the connection point between the capacitor C□, the thermistor TH as a thermal resistance element that functions as a sensor, and a series-parallel circuit of resistors R1sR2, the cathode of PUTQ2 is connected to the negative line, and the gate of PUTQ2 is connected to the connection point between diode D2 and diode D3 of series-connected diodes D2 to D4.

The oscillation frequency of this temperature-frequency converter 8 is PUTQ2
It is approximately determined by the gate voltage of , and the time constant of the charging circuit consisting of the combined resistance of capacitor C1, thermistor TH, and resistor R1tR2.

Therefore, if the oscillation frequency when the temperature of the temperature monitoring section P is within the specified value (i.e., normal) is fo, and the oscillation frequency when it exceeds the specified value (i.e., abnormal) is fH, then temperature monitoring When the temperature-resistance characteristic of the sensor TH that is close to or in close contact with the part P is of positive polarity, fo>fH, and when it is negative polarity, fo<fH.

A specific example of the former case is f. 〉3KHz, 3
It is set such as 00Hz<fH<3KHz.

By the way, PUTQ2 becomes an anode when its anode voltage rises and becomes approximately equal to the gate voltage.

Since conduction occurs between the cathodes and the charge in the capacitor C0 of the charging circuit is discharged to cause relaxation oscillation, fluctuations in the gate voltage and the voltage applied to the charging circuit, that is, the line voltage, are caused by the oscillation frequency of the temperature-frequency converter 8. It appears as a fluctuation in

Therefore, in this embodiment, since the power supply section 9 is not specially provided with a voltage stabilizing means as described later, the output voltage of the power supply section 9 is stabilized by using the forward characteristics of the diodes D2 to D4 connected in series. Fairly stable line voltage 2. IV
(0,7VX3) and also performs temperature compensation for the temperature-frequency converter 8.

That is, the temperature coefficient of the oscillation frequency of the relaxation oscillation circuit using PUT is positive, and as the ambient temperature rises, the oscillation frequency increases.

On the other hand, as is clear from the above, the PUT relaxation oscillation circuit has a characteristic that the oscillation frequency decreases as the line voltage decreases.

However, in this embodiment, as the ambient temperature rises, the forward voltage of the diodes D2 to D4 decreases, and therefore the line voltage decreases, so the fluctuation in the oscillation frequency of the PUT relaxation oscillation circuit due to the ambient temperature is canceled out. and temperature -
The oscillation frequency of the frequency converter 8 is temperature compensated over a wide temperature range.

In addition, since diodes, especially silicon diodes, can flow large surge currents, high disturbance voltages such as impulse voltages applied from outside the transmitting device 2 are absorbed by the series circuit of diodes D2 to D4, and the carrier wave oscillator 7
There is also the effect that the temperature-frequency converter 8 is protected from disturbance voltage.

The carrier wave oscillation section 7 includes a crystal resonator X and a variable capacitance diode D1 as a base of a transistor Q1.

This is an oscillation circuit connected to the emitter circuit, and the oscillation frequency (
The carrier wave frequency (fc) is selected to be a different frequency for each transmitter, for example, in the range of 52 to 54 MHz.

Then, the variable capacitance diode D0 of this carrier wave oscillation section 7
The output of the temperature-frequency converter 8 is applied to the anode of the transistor Q1 through the resistor R6, and the carrier wave fc is FM-modulated by the output of the temperature-frequency converter 8, and is applied to the transmitting antenna of the tank circuit of the collector circuit of the transistor Q1. Temperature information radio waves 5 are radiated from an inductor L that also serves as a temperature information radio wave 5.

Note that the carrier wave fc of the carrier wave oscillation unit 7 is the temperature information signal f
.

, fH is the induced ripple voltage superimposed on the line voltage (
As will be described later, it is also subjected to FM modulation by a signal (having a frequency fr twice the AC frequency flowing through the electrical system 1).

The power supply section 9 includes a bridge rectifier circuit including a transformer T electromagnetically coupled to the electric line (bus line) 10 of the electrical system 1, and diodes D5 to D8 that rectify the alternating current voltage induced in the secondary winding N of the transformer T. and a capacitor C2 for smoothing the DC output of this bridge rectifier circuit.

By the way, it is well known that the secondary voltage of the transformer T is proportional to the product of the number of turns of the secondary winding N and the magnetic flux interlinked with the secondary winding N.

In other words, if the number of turns of the secondary winding N is constant, it is approximately proportional to the magnetic flux density in the core.

However, since the magnetic flux density in the core changes depending on the current value flowing through the electric line 10 of the electrical system 1, if the current value of the electric line 10 changes widely, the secondary voltage of the transformer T and thus the transmitter 2 The line voltage changes widely, which is undesirable.

In order to avoid such inconvenience, it is effective to determine the dimensions and material of the core so that the core K is magnetically saturated within a certain range of the current value of the electric circuit 10.

In this way, even if the current in the electrical circuit 10 fluctuates within a certain range, the magnetic flux density in the core, that is, the magnetic flux interlinked with the secondary winding N, hardly changes, so the output voltage of the transformer T As a result, the amount of fluctuation in the line voltage of the transmitter 2 can be suppressed.

However, heat generation in the core and waveform distortion of the secondary voltage should be taken into consideration.

Fig. 3 shows an embodiment of the transformer T based on the above idea, in which the secondary winding N is wound around the bobbin B, and the core and the pot body are inside the bobbin B. It passes through the hole and is wound around the electric circuit 10 several times.

This transformer T has an extremely simple structure and has the advantage that the transformer T can be fixed to the electric circuit 10 by/with the pot body.

Note that tl and t2 are lead terminals of the secondary winding N.

The receivers 3□ to 3sE receive the temperature information radio waves 51 to 5n sent from the transmitters 21 to 2n, and each transmitter 21 to 2
Displays temperature information at temperature monitoring points in electrical systems 11 to 13 corresponding to n (in addition to visual display using lamps, etc., this means converting temperature information into a physical quantity that is easy for people or equipment to identify) .

(the same applies hereinafter). In FIG. 4, one embodiment of the receiving device 3 will be described.

In the figure, 11 is a frequency mixing circuit, 12 is a local oscillation circuit, and both circuits 11 and 12 constitute a frequency conversion circuit.

The local oscillation frequency of the local oscillation circuit 12 is sequentially switched to a frequency corresponding to each transmitter by a switch circuit 14 controlled by a scanning circuit 13.

The frequency mixing circuit 11 mixes the local oscillation signal sent from the local oscillation circuit 12 and the corresponding temperature information radio wave 5 from each transmitter 2, and converts the mixture into an intermediate frequency signal.

So-called superhetero gain detection is performed.

The output of the frequency mixing circuit 11 is amplified by an intermediate frequency amplification circuit 15, demodulated by an FM demodulation circuit 16, and sent to a discrimination filter circuit 17.

This discrimination filter circuit 17 has a frequency fo.

A band pass filter 170t17H217L*17r that passes the fH, fr and fL signals, and a level comparison circuit 25 that converts the output from each filter into a level signal.
Consists of.

The outputs output through each of these filters 17 o, 17 Hs 17 L and the output output through the filter 17 r are AND gates 18oy 18Ht 18
The logical product output is temporarily stored in the display panel 19.

The display panel 19 shows the number lamp No. of the transmitter 2, the temperature normal lamp OK, the temperature abnormal lamp AL, and the transmitter abnormal lamp T.
R are arranged.

This display panel 19 is divided by a switch circuit 20 synchronized with the switch circuit 14, and number lamps NO corresponding to the transmitters 2 selected by the frequency mixing circuit 11 are sequentially lit.

Then, each lamp corresponding to the lit number lamp NO is OK and AL.

Temperature information etc. are displayed by TR.

That is, when the temperature of the temperature monitoring point P of the electrical system 1 corresponding to the selected transmitter 2 is within the specified range, the AND gate 180 outputs an output, the temperature normal lamp OK lights up, and the temperature monitoring point P When the temperature rises above the specified value, an output is output from the AND gate 18H and the temperature abnormality lamp AL is lit.

Furthermore, due to disconnection of the thermistor TH of the transmitter 2, etc., the operation of the temperature-frequency converter 8 becomes abnormal, resulting in an unspecified frequency f1,
When oscillation occurs, an output is output from the AND gate iaL and the transmitter error lamp TR is lit.

Along with these lamp displays, alarm signals for temperature abnormalities, transmitter number signals, etc. are sent to the central monitoring device 4.

Note that in this embodiment, the filter 17o.

By inputting the AND output of the outputs of 17H and 17L and the output of the ripple 17r to the display panel 19, an abnormality in the transmitter itself is detected and malfunction of the display panel 19 due to external noise is prevented.

That is, since the temperature information radio wave 5 emitted from each transmitter 2 includes the ripple component r as described above, each ant game) 18o is applied to the temperature information radio wave 5.

18H218L is opened by the output of filter 17r,
The output of each filter 170t 17H, 17L is input to the display panel 19 through AND gates 18o, 18Hl 18L.

However, since no signal is generated on the output side of the filter 17r for external noise that does not include the ripple component r other than the temperature information radio wave 5, the AND gate 180tl13Hy18L
is in a closed state, and even if external noise causes filter 17
Even if a signal is generated on the output side of o17Ht17L, this signal is not input to the display panel 19.

Therefore, the display panel 19 responds only to the temperature information radio waves 5 transmitted from the transmitter 2, and reliability is greatly improved.

It should be noted that the present invention is not limited to the configuration of the above-mentioned embodiments, but can be implemented in a wide range of embodiments.

For example, if the electrical system uses DC voltage, power for the transmitter can be supplied directly from the electrical circuit of the electrical system.

Further, the transmitter can have any configuration other than the above-mentioned embodiments, and as the temperature-sensitive element, various temperature-measuring resistors, thermocouples, or even temperature switches can be used in addition to the thermistor.

Further, in the above embodiment, the transmitting device is divided into three groups, a receiving device is provided for each group, and each receiving device is connected to a central monitoring device by a cable to centrally monitor the temperature of the entire electrical system. However, depending on the scale of the electrical system, it is possible to further divide the transmitting devices into multiple groups or to combine them into one group, and it is not necessary to provide a central monitoring device.

Furthermore, in the above embodiment, one temperature sensing element is provided in the transmitting device so that the temperature of one temperature monitoring point is detected by one transmitting device, but multiple temperature sensing elements may be used as necessary. An element may be provided in each transmitting device.

The remote temperature monitoring system of the present invention is as described above, and can constantly monitor the temperature of various parts of the electrical system without stopping the operation of the electrical system, and also connects the transmitter and receiver using radio waves. At the same time, since the transmitter is supplied with power from the electrical system to be monitored, it can be applied to temperature monitoring of large-scale, high-voltage electrical systems without any problems, resulting in extremely large effects.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing an embodiment of the remote temperature monitoring system according to the present invention, Fig. 2 is an electric circuit diagram showing an embodiment of the transmitting device, and Fig. 3 is a circuit diagram between the power supply of the transmitting device. FIG. 4 is a perspective view showing one embodiment of the transformer used, and a block diagram showing one embodiment of the receiving device. 1.11~13...Electrical system, 2,21~2n
...... Transmitting device, 3, 31-33... Receiving device, 4... Central monitoring device, 10...
・Electrical system electrical circuit, P...Temperature monitoring point of the electrical system.

Claims (1)

[Claims] 1. A transmitting device installed close to a temperature monitoring point in an electrical system, and a temperature monitoring device installed at a distance from this transmitting device to receive temperature information radio waves transmitted from the transmitting device and corresponding to the transmitting device. In a remote temperature monitoring system for an electrical system, the transmitting device includes a power supply unit having a transformer electromagnetically coupled to a power transmission path of the electrical system, and a receiving device for displaying temperature information at the temperature monitoring location. a temperature-frequency converter that converts a characteristic change of the temperature-sensitive element whose characteristics change depending on temperature into a frequency; and a temperature information radio wave containing a ripple component of the power transmission line based on the output of the temperature-frequency converter. The receiving device includes a demodulation circuit to which the received output of the temperature information radio wave is supplied, and an output of the demodulation circuit to which at least a normal frequency fQ, an abnormal frequency fH, and a ripple frequency f are supplied.
be comprised of a frequency discrimination circuit that discriminates r, a gate circuit that gates the normal frequency output and abnormal frequency output of the frequency discrimination circuit with ripple frequency output, and a display device to which the output of the gate circuit is supplied. A remote temperature monitoring system for electrical systems featuring: