JPH06284049A - Data transmission equipment using electric circuit - Google Patents

Abstract

PURPOSE:To evade a collision problem in carrier frequency and to increase the number of set data transmission circuits by detecting a measuring signal between a ground side electric circuit and ground and modulating a carrier signal by a time slot synchronized with voltage impressed between the electric circuit and the ground so as to use the carrier signal time-dividedly. CONSTITUTION:A measuring low frequency signal between the ground side electric circuit connected to an electric circuit 2 through the transformer of each transmission circuit and the ground is detected by a detection circuit 52. A carrier with frequency F1 or the like is modulated and transmitted by a data signal 58 in the former half part of one period in the detected signal. Similarly a carrier with frequency F1 or the like is modulated and transmitted in the latter half part of the detected signal. The number of set data transmission lines can be increased while evading the collision of carrier frequency by using a carrier signal time-dividedly by a time slot synchronized with the measuring low frequency signal. In addition, demodulation is similarly executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an apparatus for transmitting data from a plurality of points on an electric line by using an electric line.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a data transmission device using a conventionally proposed electric circuit. High-voltage electricity is transformed into low-voltage electricity by the power receiving transformer T.
The electric line 2 is grounded to the ground point E2 of the second type grounding work by the ground wire 4, and load devices 5, 6 and the like are connected between the electric lines 1 and 2 and between the electric lines 2 and 3. The carrier frequencies used in the data transmission circuits 7, 8 and 9 on the electric path are different from each other, and none of the carrier frequencies is set to match the harmonic frequency of the commercial frequency f0. Data transmission circuit 7-
In 9, the respective carrier frequencies F1, F2, F3 are modulated by the transmission data 10, 11, 12, and the transmission circuit output current is injected via the capacitor C between the ground side electric circuit 2 and the ground point E3 of the third type grounding work. To do. The output currents of the respective transmission circuits injected into the electric circuit in this way flow back to the ground line 4, and after the currents are detected by the current transformer 19 coupled to the ground line 4, filters having center frequencies of F1, F2, and F3, respectively. Demodulation circuit 1 separated and extracted by 13, 14 and 15 and provided at the output end of each filter
6, 17, and 18 demodulate the received data. However, in the conventional device, the carrier frequency assigned to the modulator of each data transmission circuit is a frequency that does not match the harmonic component of the commercial frequency, that is, the even number of harmonics of the commercial power source ±
Since (1/3 * commercial frequency) is generally selected as the carrier frequency, when a large number of transmission circuits need to be installed on the same electric circuit, if the upper limit of the carrier frequency is set to 10 kHz, for example, the carrier frequency that can be practically selected is It was about 170 to 190 waves, and it was difficult to install a transmitting circuit beyond this. For example, an in-patient installed in a hospital is provided with a transmitter for transmitting IDs to inpatients, and an ID sent by each in-patient to a data transmission circuit installed in the in-circuit.
When a conventional data transmission device is used in a system for confirming where each person is in the hospital by providing a circuit for receiving the information and transmitting each person's ID through the data transmission circuit, the data transmission circuit Since the number of installations is limited by the selectable carrier frequency, the conventional system should be applied when there are many data transmission circuit installation points, that is, inpatient ID reception points, as in large hospitals. Was difficult. Further, when the carrier frequencies of several data transmission circuits are made the same, a so-called "collision problem" occurs, and in order to avoid this, complicated processing is required, and there is a problem that the device becomes expensive. .

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional problems, and compared with a conventional data transmission apparatus, data transmission can be performed without causing a carrier frequency collision problem. An object of the present invention is to provide a data transmission device capable of increasing the number of transmission circuits installed.

SUMMARY OF THE INVENTION In order to achieve this object, a data transmission apparatus according to the present invention includes an electromagnetic induction or series coupling of a measuring signal voltage having a frequency f1 different from a commercial frequency f0 to an electric line via a ground wire of a transformer. An electric circuit provided with a device for measuring the insulation resistance between the electric circuit and the earth by detecting a component in phase with the measuring signal voltage in the leakage current component of the frequency f1 which is applied by the In the data transmission device used for, in the extension of the electric path, a circuit for detecting the measuring signal voltage existing between the ground side electric path of the electric path and the ground, and a predetermined time slot synchronized with the measuring signal voltage. A carrier signal of frequency Fn is modulated with transmission data, and a transmitter circuit for injecting the modulated carrier signal current between the ground side electric circuit and the ground and a carrier signal current of frequency Fn flowing back to the ground line are detected. And a receiving circuit for separating the signal of the predetermined time slot of the measurement signal voltage from the signal obtained by demodulating the carrier signal current and detecting the received data, and a plurality of carrier signals of frequency Fn are provided. The data transmission circuit is used in a time division manner to transmit data.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a diagram showing an embodiment of a data transmission apparatus according to the present invention. The same parts as those in FIG. 4 are designated by the same reference numerals, and the description thereof will be omitted. Power receiving transformer T
Of the low-voltage side electric lines 1, 2, and 3 of the electric line 2, the electric line 2 is grounded to the ground point E2 of the second-class grounding work via the ground wire 4, and a low-frequency signal that generates a signal of a frequency f1 different from the commercial frequency f0. The output of the generator 35 is applied as a low frequency voltage for measurement to the ground line 4 via a power amplifier 36 and an injection transformer 37. Insulation resistances R1, R2 of electric circuits 1, 2, 3
The zero-phase current transformer 30 detects the current flowing back to the ground line 4 via R3 and the electrostatic capacitances C1, C2, and C3, and after amplifying its output by the amplifier 31, the component of the frequency f1 is detected. It is applied to the filter 32, and the output of the filter 32 is supplied to one input end of the synchronous detector 33. Further, the output of the low frequency signal generator 35 is supplied to the other input terminal of the synchronous detector 33 as a reference phase signal. The output of the amplifier 31 is the bandpass filter 3 of the data receiving circuit 25.
The frequency components of the center frequencies F1 and F2 are separately detected. The outputs of the filters 39 and 40 are applied to the input ends of demodulators 41 and 42, respectively, and the outputs of the demodulators 41 and 42 are supplied to one input ends of the data separation circuits 43 and 44. In addition, the data separation circuits 43 and 44
The output of the low-frequency signal generator 35 is supplied to the other input terminal of the through a waveform shaping circuit 38. Further, the first, second and third data transmission circuits 48, 49, 5 are provided on the extension of the electric path.
0 is inserted between the grounding side electric circuit 2 and the grounding wire E3 for the third type grounding work via, for example, a capacitor. FIG. 2 shows each data transmission circuit in detail. One input end of the primary side of the transformer 53 is connected to the ground side electric circuit 2 via the capacitor C, and the other input side of the primary side of the transformer 53 is connected. The input end is connected to the ground point E3 of the third type grounding work via the resistor 54 for limiting the injection current. One input end of the high input impedance amplifier 51 is connected to one input end of the transformer 53, and the other input end of the high input impedance amplifier 51 is connected to the ground point E3 of the third-class grounding work to connect the electric circuit. The high input impedance amplifier 51 detects the signal voltage existing between the ground point E3 and the ground point E3, and the output terminal thereof is connected to the detection circuit 52 for detecting the low frequency signal for measurement of the frequency f1. Therefore, the measuring low-frequency signal output 57 of the frequency f1 is obtained at the output end of the detection circuit 52, and is used as a control signal for inputting the transmission data 58. The transmission data 58 is input to a modulator 56 that modulates a carrier signal having a frequency Fn (n = 1 or 2), the output of the modulator 56 is amplified by an amplifier 55, and then the transformer 53.
Is supplied to the secondary side of. The operation of the data transmission apparatus configured as described above will be described in detail below with reference to the waveform chart shown in FIG. In FIG. 1, A is a zero-phase current transformer 3
0, amplifier 31, filter 32, synchronous detector 33, low frequency signal generator 35, power amplifier 36, injection transformer 37
An insulation resistance measuring device for measuring the insulation resistance of an electric circuit consisting of the following. In the data transmission device according to the present invention, an explanation will be given taking as an example the one in which some of the components of the insulation resistance measuring device A are shared. ing. The insulation resistance measuring device uses a low frequency signal for measurement (for example, f = 12.5H) having a frequency f1 in the electric circuit.
z) is applied, the current flowing back through the ground impedance is detected by this signal, and the component in phase with the applied voltage is detected by the synchronous detector 33. Regarding such an insulation resistance measuring device, For example, Japanese Patent Publication No. 2-43409
Etc., and detailed description thereof will be omitted. By the way, as the low frequency signal of the frequency f1 applied to the electric line, a low frequency signal having the same amplitude and the same phase between the ground and all the electric lines is selected. Therefore, if the voltage between an arbitrary point on the electric path and the ground is detected by the high input impedance amplifier 51 and the component of the frequency f1 is extracted by the low frequency signal detection circuit 52, the detection as shown in FIG. Waveforms can be obtained. Further, if the detected waveform is shaped, the output waveform as shown in FIG. 3B is obtained, and if the output waveform is logically inverted, the waveform as shown in FIG. 3C is obtained. In the embodiment of the data transmission apparatus according to the present invention, the case where the carrier signal of the same frequency Fn is shared by two transmission circuits is shown. That is, the frequency f1 shown in FIG.
The phase of one cycle of the signal is divided into two, the first transmission circuit 48 performs data transmission using the carrier frequency F1 in a half cycle at t1 <t <t2, and a half cycle at t2 <t <t3. At the second transmission circuit 49, the carrier frequency F
1 is used to perform data transmission. Therefore,
In the first transmission circuit 48, the timing control signal shown in FIG.
The transmission data 58 input to the transmission circuit 48 is controlled using the waveform signal shown in FIG. 3B, and the second transmission circuit 49 uses the waveform signal shown in FIG.
It is set in advance to control the transmission data to be input to. At each transmission circuit installation point, the carrier signal current injected between the ground-side electric circuit 2 and the ground is modulated by the transmission data. As the modulation method, for example, amplitude modulation may be used. In this case, the outputs of the first transmission circuit 48 and the second transmission circuit 49 have the waveforms shown in FIGS. 3D and 3E, respectively. On the other hand, if another carrier frequency F2 is used in the third transmission circuit 50 and the signal shown in FIG. 3B is used for timing control, the waveform of the current that the transmission circuit 50 injects between the ground side electric circuit and the ground is Figure 3 (f)
As shown in. These currents flowing back to the ground line 4 are detected by the zero-phase current transformer 30 coupled to the ground line 4, and separated and extracted via the filters 39 and 40, the output of the filter 39 for detecting the frequency F1 component. Waveform is Figure 3
As shown in (g), the output waveform of the filter 40 for detecting the frequency F2 component is as shown in FIG. 3 (h), and the output terminals of the demodulators 41 and 42 are shown in FIG. 3 (i), respectively.
And the output waveform shown in FIG. 3 (j) is obtained, and each demodulator 4
The 1 and 42 outputs are supplied to the data separation circuits 43 and 44. On the other hand, the output of the low-frequency signal generator 35 is supplied to the data separation circuits 43 and 44 via the waveform shaping circuit 38. Therefore, the data separation circuits 43 and 44 have signals corresponding to those shown in FIG. Are used as time slots for data separation. At the output terminal 45 of the data separation circuit 43, the carrier frequency is F
The data which is one component and is received in the first half cycle of the signal supplied from the waveform shaping circuit 38 is output. Further, to the output terminal 46 of the data separation circuit 43, similarly, the carrier frequency is the F1 component, and the data received in the latter half cycle of the signal supplied from the waveform shaping circuit 38 is output. That is, from the output terminal 45, the first transmission circuit 48
The data sent from the output terminal 46 is output after being demodulated as shown in FIG. 3 (k).
The data sent from the second transmission circuit 49 is output as shown in FIG. Similarly, the output terminal 47 of the data separation circuit 44 outputs the data transmitted from the third transmission circuit 50 as shown in FIG. It should be noted that a desired start bit and stop bit may be inserted at the start and end of data transmission. As described above, a low-frequency signal having a frequency different from the commercial frequency is applied to the electric circuit, a time slot on the transmission / reception side is assigned based on the low-frequency signal, and data is transmitted / received to transmit the same carrier wave to a plurality of transmission circuits. Therefore, the number of transmission circuits installed can be significantly increased. still,
In the above-mentioned data transmission circuit, the case where the data transmission rate matches the frequency f1 of the measuring low frequency signal has been described. However, if the number of time slots is increased in synchronization with the measuring low frequency signal frequency f1, higher speed data can be obtained. Obviously, transmission is also possible. However, as a matter of course, the frequency band of the signal current sent by each transmission circuit increases,
There is an upper limit to the data rate that can be used with line noise, especially current noise flowing back to the ground line. Further, in the above embodiment, the case where the phase of the low frequency signal for measurement is divided into two has been described, but the present invention is not limited to this, and the data transmission device is configured to divide the phase into four for data transmission. If the four data transmission circuits have the same carrier frequency F,
1 can be shared. Further, although a part of the insulation resistance measuring device of the electric line is shared in the above embodiment, if this device is not provided, a low-frequency signal of frequency f1 is simply applied to the ground line and the carrier signal current flowing back to the ground line is used. Can be detected by a zero-phase current transformer, and the output current of the transmitter circuit is injected between the ground-side electric circuit and ground. It is possible to obtain However, in this case, it is necessary to note that the leakage current of the commercial frequency increases and the leakage breaker or the like may malfunction. It is also possible to use a commercial frequency as a reference signal for time slot creation, instead of applying a low frequency signal to the electric circuit.

The same carrier wave can be shared by a plurality of transmission circuits in a time-division manner, and a large number of sensors and the like are installed near the electric line to collect these data.
It is possible to provide economical data transmission.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a data transmission device according to the present invention.

FIG. 2 is a diagram showing a data transmission circuit of the data transmission device according to the present invention.

FIG. 3 is a diagram showing waveforms at various parts of the data transmission device according to the present invention.

FIG. 4 is a diagram showing a configuration of a conventional data transmission device.

[Explanation of symbols]

1, 2, 3 ... Electric circuit, 4 ... Ground wire, 25 ...
・ Data receiving circuit, 48, 49, 50 ... Data transmitting circuit A ... Insulation resistance measuring device

Claims (3)

[Claims] 1. A leakage current component of frequency f1 which is returned to the ground line by applying a measurement signal voltage of a frequency f1 different from the commercial frequency f0 to the electric line through a ground line of the transformer by electromagnetic induction or series coupling. In the data transmission device used for the electric line where a device for measuring the insulation resistance between the electric line and the ground by detecting the component in phase with the signal voltage for measurement is installed, on the extension side of the electric line, the ground side of the electric line The measuring signal voltage existing between the electric path and the ground is detected, the carrier signal of the frequency Fn is modulated with the transmission data at a predetermined time slot synchronized with the measuring signal voltage, and the modulated carrier signal current is detected. A data transmission circuit for injecting between the ground-side electric circuit and the ground, and a carrier signal current of a frequency Fn that flows back to the ground line is detected, and the measured signal is obtained from a signal obtained by demodulating the carrier signal current. And a data receiving circuit for detecting received data while separating a signal of a predetermined time slot of pressure, and a plurality of data transmitting circuits time-divisionally use a carrier signal of frequency Fn to transmit data. A data transmission device using a characteristic electric circuit. 2. The circuit according to claim 1, further comprising a circuit for applying the measuring signal voltage having a frequency f1 different from the commercial frequency f0 to the ground line by electromagnetic induction or series coupling. Data transmission device using electric circuit. 3. A low frequency signal applying circuit for applying a signal voltage of a frequency different from a commercial frequency to an electric line, and the low frequency signal voltage existing between the ground side electric line of the electric line and the ground on the extension of the electric line. And a carrier wave signal having a frequency Fn is modulated with transmission data in a predetermined time slot synchronized with the low frequency signal voltage, and a modulated carrier signal current is injected between the ground side electric circuit and the ground. Detecting a carrier signal current having a frequency Fn that flows back to the ground line, separating a signal of a predetermined time slot of the low frequency signal voltage from a signal obtained by demodulating the carrier signal current, and detecting received data And a data receiving circuit for
A data transmission device using an electric circuit, wherein a plurality of data transmission circuits time-divisionally uses a carrier signal of frequency Fn to transmit data.