JPS61112538A - Transmitter for monitor signal - 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 (Field of Industrial Application) The present invention relates to a method of transmitting an alarm signal obtained by monitoring the insulation monitoring state of an electrical circuit.

(Prior art) In general, the insulation condition of the secondary low-voltage circuit of a transformer that transforms high-voltage electricity into low-voltage electricity is monitored while it is live, or abnormal temperature rises in the transformer are monitored to prevent accidents. Efforts are being made to prevent such occurrences and ensure a stable power supply. On the other hand, these monitoring devices are installed in the power receiving room where the transformer is installed, but the power receiving room is generally not permanently staffed. Alternatively, it is necessary to transmit it to a control center, etc.

Conventionally, this alarm signal has been transmitted using, for example, the second terminal of the transformer.
Low-frequency signals of multiple frequencies corresponding to multiple alarm signals to be transmitted via the grounding wire for grounding work, or a combination thereof, are applied to all electrical circuits, and in offices etc., low-voltage electrical circuits (e.g. By detecting the low frequency signal voltage induced between the grounding phase (earth phase) and the military class 3 grounding line, and separating it with a plurality of receiving filters, it is possible to detect which alarm signal is being transmitted. It was outputting a judgment as to whether the

(Problems to be Solved by the Invention) However, in the conventional alarm signal transmission method described above, the receiving section requires a plurality of receiving filters corresponding to the above-mentioned unique frequencies, and the transmitting section requires a plurality of low-frequency signals. Since the signals are transmitted simultaneously, the circuit for applying the voltage to the electric circuit becomes complicated, making the device expensive and reducing reliability.

(Means and operations for solving all the problems) The present invention has been made to solve the problems of the conventional method, and it allocates a unique frequency to each alarm signal to be transmitted, and transmits it to the electric line. At the same time, the reception section is equipped with a filter whose pass characteristic can be varied, and the center frequency of the filter is sequentially switched at a constant period To to detect each frequency component. If a low frequency signal is detected, it is configured to determine that a low alarm signal corresponding to that frequency has been received.

It is assumed that the unique frequency signals corresponding to each of the above-mentioned alarms are transmitted continuously for a period longer than the period To.

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

Figure @1 is a block diagram showing an entire embodiment of the present invention. In the figure, T indicates a transformer that transforms high-voltage electricity into low-voltage electricity, and the secondary low-voltage circuit is a single-phase three-wire type, 1.3 is the ungrounded circuit on the low-voltage side, and 2 is the grounded circuit (grounded The electric line 2 is grounded by a grounding wire 4 of type 2 grounding work at a transformer.

In this embodiment, the present invention is applied to such an electrical circuit, and an alarm signal generated by a monitoring device 5 installed near the transformer T and monitoring insulation by some means not shown in the drawings is shown. The case is shown in which the alarm signal is transmitted to an alarm signal receiving device 6 installed in an office or the like located on the extension of all the electric lines.

First, the alarm signal output from the monitoring device 5 includes, for example, normal, caution, and ! There are three types of warnings: ``Normal'' indicates that the insulation condition is normal, ``Caution-1'' indicates a sign of deterioration of the insulation condition, and ``Warning'' indicates that the insulation has deteriorated and is dangerous. The status shall be indicated respectively. In this embodiment, one of these plurality of signals is transmitted, and when there is no abnormality, a "normal" signal is always transmitted. The transmission g7 has its own frequency f1.corresponding to the three types of signals mentioned above. All three low frequency signals f2 and f3 are generated and applied to the ground line 4 via a transformer 8 coupled to the ground line 4, thereby propagating the low frequency signals to the electric line 2.

When applying low-frequency signals to the receiver, they are sent out in accordance with the duration of each signal, but in consideration of detection at the receiving section, each signal applied to the transmitting section is held continuously for a time Tl. Even if the signal generated by the monitoring device 5 is a short-time signal, the low-frequency signal is transmitted for a minimum time T1, and a signal shorter than time T+ is continuously held until time T1 so that other signals are not transmitted during transmission. Even if it becomes necessary to send a signal, 9
The transmission continues until time T1.

It shall have a function to send out other signals after the sending is completed. Note that the frequency f1. It is assumed that fZ and f3 are frequencies that do not match the commercial power supply frequency and its harmonic frequencies.

On the other hand, in the alarm signal receiving device 6.

For example, the above-mentioned low frequency signal induced between the ground phase TfL path 2 and the grounding wire 9 of type 3 construction (general ground may be used) is derived to the receiving circuit 12 via the connecting line 11 in which the capacitor 10 is inserted. do.

This receiving circuit 12 has a high input impedance so as not to affect the electrical circuit connecting it, and is provided with three output terminals, so that the signal frequencies f1+f2 and f3 propagated through the electrical circuit 2 can be adjusted. The structure is such that three warning signals, ``normal'', ``warning'', and ``warning'', are output in response to the presence or absence of the device.

The above-mentioned capacitor C is a direct current blocking component designed to make it easier to inspect the insulation of this electrical circuit using a megger or the like.

The configuration of this receiving circuit 12 is, for example, as shown in FIG.

That is, FIG. 2 is a block diagram showing an embodiment of the receiving circuit 12 of the receiving section 6 of the above-mentioned Army 1, and includes a variable frequency filter 13 whose passband frequency is sequentially switched to f1, fl, and f3, and its output. signal? A rectifier circuit 14 that rectifies and converts it into a DC signal and a control circuit 15 that identifies which frequency component the DC signal is based on are connected in a subordinate manner, and the frequency variable filter 13 and the control circuit 15 are connected in a subordinate manner.
It consists of a synchronization circuit for timing with the

Note that the frequency variable filter mentioned above has a selected passing frequency f
1, fl, and f3 at predetermined intervals t.

This cycle is the period T. (
To=3to), it functions repeatedly.

An "N-way filter" is suitable as such a variable frequency filter, and an example of this is described in US document 1967.
This is detailed in the July 24 issue of Electronics, 2015, so the explanation here will be omitted.

It is desirable that the selection characteristic of the above-mentioned filter be steep enough to remove noise due to commercial power frequency components or their harmonic components.

To explain the operation of the friend monitoring signal transmission device configured as described above, first, on the transmitting side, the insulation state of the electrical circuit is identified by a mental monitoring device (not shown in the drawings) as described above, and a "normal" signal is determined according to each state. ” ``Caution'' or ``Warning'' is determined, but when it is ``normal'', a low frequency signal of frequency f1 is continuously emitted.

When a "caution" or "warning" state occurs, a low frequency signal fl or f3 is sent out instead of f1.

On the other hand, in the receiving section 6 that detects this, the nine frequency variable filter 13 sequentially scans and extracts three low frequency signals of f1, fl, and f3, and the output is sent to the rectifier circuit 14IC.
Therefore, it converts into DC, and if there are components corresponding to these, a DC signal is output to the next stage control circuit.

The frequency variable filter 13 and the control circuit 15 are the synchronous circuit 1
The DC signals synchronized by the timing pulse a outputted by the control circuit 15 are f1, fl, and f3.
It is determined which frequency component the signal corresponds to, and a corresponding signal of "normal", "caution", or "warning" is outputted to the output terminal 17.

These three signals may be displayed, for example, as an alarm by an accessory device (not shown), or may be further transmitted to a control center via a modem or the like.

The relationship between the time T6 for transmitting each signal from the transmitting section and the timing error of the frequency variable filter 13 of the receiving section is determined by considering the time required for this detection, T o > T
The transmitter controls the signal transmission time so that the signal transmission time becomes 1.

In addition, in determining the presence of the above-mentioned alarm signal, increasing the number of cycles in which the relevant signal exists can reduce the rate at which the signal is distorted and the determination is output.
In the transmitting section mentioned above! It is necessary to lengthen the Ai holding time T+'r.

(Effects of the Invention) Since the present invention is constructed and operated as described above, it simplifies the transmitting section and receiving section of a device that transmits monitoring signals, etc., and enables accurate transmission of alarm signals. brings about the effect.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing an embodiment of the receiving circuit of FIG. 1.3......Ungrounded electrical circuit, 2...
・・・・・・Grounding circuit, 4 and 9・・・・・・・・・
ground wire. 5...Monitoring device, 6...Bright...Receiving device. 7......Transmission section, 8.Injection transformer 10...Capacitor, 11...
・・・・・・Connection line. 12......Reception circuit, 13...
... Frequency variable filter A'Yu + 14...
... Rectifier circuit. 15-... Control circuit, 16... River...
...Synchronous circuit. 17...-... Alarm signal output terminal, T...
...Transformer, E2 and E3...
...Grounding point, patent applicant Toyo Tsushinki Co., Ltd. P! LHrEJ Figure 2

Claims (1)

[Claims] When transmitting various alarm signals output from monitoring equipment, etc., the frequency of the commercial power supply differs from the commercial power supply frequency corresponding to the various alarm signals mentioned above, to the power line connected to the receiving transformer via a grounding wire that has undergone type 2 grounding work. Low frequency signals f_1, f_2,・
...f_N (N is an integer) is applied, and in a receiving device installed on an extension of the electric path, the passband frequency is applied to the low frequency signal f_1 as means for detecting the low frequency signal. , f_2, . . . f_N is used, and any one of the low frequency signals f_1, f_2, . 1. A monitoring signal transmission device characterized in that when a low frequency signal is detected, it is determined that an alarm signal corresponding to the detected low frequency signal has been sent.