JPH0438475A - Amplifier type instrument transformer - Google Patents

Abstract

PURPOSE:To obtain a small-size transformer having the large output voltage matched with an electronized apparatus and reduced in power consumption by modulating the voltage waveform divided by a main capacitor and a voltage dividing capacitor to a pulse train in a modulation part and transmitting the pulse train to a demodulation part by a transmission apparatus using an optical fiber cable. CONSTITUTION:The voltage 20 obtained by dividing voltage by the main capacitor 2 and voltage dividing capacitor 3 of an amplifier type instrument transformer is inputted to a modulation part 15 through a voltage amplifying part 4 to be converted to a pulse train 21. This pulse train 21 is converted to an optical pulse train by an E/O converter 16 and the optical pulse train is transmitted through the optical fiber cable 17 of a transmission apparatus 27 and again converted to an electric signal by an O/E converter 18 to be inputted to a demodulation part 19. By this constitution transmitting light by the optical fiber cable using the pulse train, the small-size amplifying type instrument transformer receiving no electromagnetic induction and also receiving no effect due to secular change of the light emitting element and photodetector for the transmission apparatus and matched with an electronic circuit in its output voltage and reduced in power consumption is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in an amplification type potential transformer used for measuring voltage of electrical equipment.

[Prior Art] FIG. 3 shows only one phase of an amplification type potential transformer according to the prior art. In the same figure, 1 is the main circuit conductor,
11 is an amplification type voltage transformer, which includes a main capacitor 22, a partial voltage capacitor 3. It is composed of a voltage amplifying section 4 and a power amplifying section 5. 24 is the output voltage, 6a and 6b are control cables for supplying the output voltage 24 to the load, and 8a is the load, which is composed of an electromagnetic relay, 9 electromagnetic meters 1O, and 2 electromagnetic protective relays and instruments (not shown). It is assumed that Further, 7a and 7b are a load 8a and (7) voltage input terminals.

In FIG. 3, the amplified potential transformer 11 supplies its output voltage 24 to the voltage input terminals 7a, 7b of the load 8a.
It supplies the "signal" of the magnitude of the measurement voltage and the "power". This is because the electromagnetic relay 9 and electromagnetic meter 10 constituting the load 8a are designed so that their operating energy can be obtained from the input voltage. Therefore, the magnitude of the output voltage 24 is determined by the electromagnetic relay 9 or the electromagnetic meter 1.
The power amplifying section 5 is standardized to a convenient rated value for driving 0, and the power amplifying section 5 has a function of supplying the necessary energy to the load 8a.

[Problems to be Solved by the Invention] Figure 4 shows a load 8b constructed from computerized devices such as digital protection measuring devices that are rapidly becoming popular these days.
This is an example. In the figure, 8b is a load, which is composed of a level converter 12 and an electronic circuit 13;
Reference numerals a and 7b indicate voltage input terminals, and 24 indicates an output voltage supplied from a conventional potential transformer (not shown). Further, 14a and 14b are control power input terminals, and 14a and 14b are control power input terminals.
is a control power supply device. The load 8b is the voltage input terminal 7a,
The load 8a shown in FIG. 3 is supplied with the output voltage 24 of the potential transformer through the control cables 6a, 6b
However, the load 8b in FIG. 4 is equipped with control power input terminals 14a and 14bt" and receives control power from the control power supply 14. This means that the operating energy of the load 8b is supplied from the control power supply 14. Therefore, there is no need for energy to be supplied from the voltage input terminals 7a and 7b. Further, an output voltage 24 supplied from a conventional potential transformer (not shown) is converted by a level converter 12 into a voltage 24a of a magnitude suitable for the electronic circuit 13. This is because the output voltage 24 is too large for the electronic circuit 13.

Now, if the load 8a shown in FIG. 3 is replaced with the load 8b shown in FIG.
1 is unnecessary, and the power amplifying section 5 has the drawbacks of increasing device size and power consumption, and the output voltage 24 does not match the electronic circuit 13. It is understood that there are points.

The present invention has been made in view of these points, and aims to provide an amplified voltage transformer that has an output voltage 24 that is compatible with computerized equipment, is small in size, and has low power consumption. It is something.

[Means for Solving the Problems] As a means for achieving the above object, the present invention provides a transmission device using an optical fiber cable, in which a voltage waveform divided by a main capacitor and a voltage dividing capacitor is modulated into a pulse train in a modulation section. The voltage is transmitted to the demodulator, which demodulates it back to the original voltage wave meter and supplies it to the load.

[Operations] In the present invention, since the voltage divided by the main capacitor and the voltage dividing capacitor is converted into the number of pulses and transmitted, the power consumption is lower than in the case of power amplification, and the device can be made smaller. In addition, because it is converted into a pulse train and transmitted, accuracy is not affected even if the characteristics of the light emitting element and light receiving element change over time. Furthermore, since optical fiber cables are used, the voltage is of a magnitude that matches the electronic circuit. Even if it is transmitted as is, it will not be affected by electromagnetic induction.

[Embodiment] FIG. 1 shows an embodiment of a transformer according to the present invention for only one phase. This will be explained below with reference to FIGS. 1 and 2. In FIG. 1, reference numeral 11 denotes an amplification type potential transformer according to the present invention, which includes a voltage amplification section 4° modulation section 15. Transmission device 27.
Demodulator 19. and an output amplifying section 26. The transmission device 27 includes an E10 converter 16. It is composed of an optical fiber cable 17 and an O/E converter 18.

Next, to explain the operation, the voltage 20 obtained by dividing the voltage by the main capacitor 2 and the voltage dividing capacitor 3 is input to the voltage amplification section 4, amplified to a predetermined level, and input to the modulation section 15. . The modulation section 15 converts the voltage waveform 20 shown in FIG. 2(a), which is input to the voltage amplification section 4 and amplified in level, into the pulse train 21 shown in FIG. 2(b) using a known V/F conversion technique. and output. Pulse train 2 of modulator 15
1 is input to the E10 converter 16 and optically transmitted through the optical fiber cable 17 as an optical signal 22 shown in FIG. A pulse train 23 shown in FIG. 2(d) is input to the demodulator 19. The demodulator 19 restores the pulse train 23 shown in FIG. 2(d) to the voltage waveform 25 shown in FIG. 2(e) using a known F/V conversion technique and outputs the restored voltage waveform 25 as shown in FIG. 2(e). Here, conversion is performed so that a phase difference does not occur between the voltage waveform 20 obtained from the voltage dividing capacitor 3 and the voltage waveform 25 output from the demodulator 19, and harmonic ripples are not included in the voltage waveform 25. Frequency is set. The voltage waveform 25 output from the modulation section 19 is input to the output amplification section 26, adjusted to a predetermined level, and output voltage 24 is sent to the control cable 6a,
6b to the load. Even if the light intensity of the E10 converter 16 and O/E converter 18 of the transmission device 27 changes over time, only the height of the pulse train 22 optically transmitted by the optical fiber cable 17 will change. Therefore, the density of the pulse train does not change. Therefore, there is an advantage that, in principle, no error occurs in the magnitude of the voltage waveform 25 output from the demodulator 19.

[Effects] As explained above, the present invention converts a voltage divided by a capacitor into a pulse train, performs optical transmission through an optical fiber cable, and restores the pulse train transmitted as an optical signal to its original voltage waveform. It is an object of the present invention to provide an amplification type potential transformer that is small and has low power consumption, which is not subjected to electromagnetic induction, is not affected by aging of light emitting elements and light receiving elements of a transmission device, and whose output voltage matches an electronic circuit. can.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an amplified potential transformer showing an embodiment of the present invention for only one phase, and FIG. 2 is a diagram showing the input/output waveforms of FIG. 1. FIG. 3 is a diagram corresponding to FIG. 1 showing an amplification type potential transformer according to the prior art. FIG. 4 is a diagram showing an example of electronic loads such as protection devices. 1... Main circuit conductor, 2... Main capacitor, 3...
Voltage dividing capacitor, 4... Voltage amplification section, 5... Power amplification section, 6... Control cable, 7... Load voltage input terminal, 8-... Load, 9-... Electromagnetic relay , 10...
・Electromagnetic instrument, 11...Amplified instrument transformer, 12.
...Level converter, 13...Electronic circuit, 14...Control power supply device, 14a, 14b...Control power input terminal,
15...Modulation unit, 16...E10 converter, 17...
・Optical fiber cable, 18...○/E converter, 9・
... Demodulation unit, 0... Voltage obtained from the voltage dividing capacitor, 1... Pulse train shown in Figure 2 (b), 2... Optical signal, 3... Shown in Figure 2 (d) Pulse train, 4...output voltage,

Claims (1)

[Claims] In an amplified instrument transformer that amplifies the voltage obtained by dividing the main circuit with a capacitor and outputs the measured voltage, there is a modulation section that converts the voltage waveform obtained by dividing the voltage into a pulse train, and a modulation section that converts the voltage waveform obtained by dividing the voltage into a pulse train, and converts the pulse train to the original voltage. and a demodulation section that demodulates the waveform, the modulation section and the demodulation section are coupled by a transmission device using an optical fiber cable, and the measured voltage is configured to be transmitted as a pulse train. Amplifying type instrument transformer.