JP2684780B2 - Three-phase voltage detector for high-voltage equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a three-phase power detection device for a high-voltage device for detecting a high-voltage device such as a switch.

B. Summary of the Invention The present invention is a three-phase power detection device for high-voltage equipment that performs power detection for high-voltage equipment in which three-phase currents flow, and among the detection electrodes provided near each phase conductor of the high-voltage equipment,
A phase inversion of the induced voltage phase of the electrode close to the one-phase conductor is superposed with the induced voltage of each electrode close to the other two-phase conductor, and the combined voltage is detected by a detection amplifier. The three-phase detection can be performed by a single detection amplifier that has been used conventionally by introducing the above into the circuit to determine the presence or absence of voltage.

C. Conventional technology In high-voltage equipment such as switches, three-phase non-voltage detection is used to confirm safe work and to detect electricity for the purpose of electrical interlock. Conventionally, in the detection of high-voltage equipment in which a three-phase current flows, a detection electrode is placed facing a high-voltage part such as a conductor, and the voltage generated in the electrode is captured by electrostatic induction to determine the presence or absence of voltage. Was.

D. Problems to be Solved by the Invention Therefore, in order to determine the presence or absence of voltage of all phases of a device in which a three-phase current flows by the above method, an electrode and a voltage detection amplifier must be provided for each phase. did not become.
Therefore, in order to carry out the three-phase power detection, the cost is three times as high as the one-phase power detection, and the space is also required three times.
Due to the above reasons and the fact that there are few open phase accidents, it is the actual situation that only one set of three phases is detected.

The present invention has been made in view of the above points, and an object of the present invention is to enable three-phase power detection with a single power detection amplifier and reduce the cost. To provide.

E. Means for Solving the Problems The present invention is a three-phase power detection device for a high-voltage device that detects a voltage of a high-voltage device in which a three-phase current flows, and is installed close to each phase conductor of the high-voltage device. A detection electrode, an inverting amplifier that inverts the phase of the induced voltage of the detection electrode that is provided near a predetermined one-phase conductor of the detection electrode, and another two-phase conductor of the detection electrode. An alternating voltage obtained by superposing the induced voltage of each detection electrode and the output voltage of the inverting amplifier, which are provided near the input voltage, is input, and the high voltage is obtained by comparing the rectified voltage of the alternating input voltage with a predetermined set voltage. It is characterized in that it is provided with a detection amplifier that determines the presence or absence of the voltage of the device.

F. Action The voltage induced in the detection electrode near the one-phase conductor of high-voltage equipment is inverted 180 degrees by the inverting amplifier. The phase of the voltage obtained by combining the induced voltages of the respective detection electrodes provided near the other two-phase conductors of the high-voltage equipment is the same as the output voltage phase of the inverting amplifier. Therefore, when there is a voltage in the high-voltage equipment, a voltage that is approximately twice the induced voltage from the one-phase conductor is input to the detection amplifier. Further, in the case of a phase failure of a high voltage device, the input voltage of the detection amplifier becomes smaller than the voltage which is about twice as large as the above. Furthermore, when there is no voltage in the high-voltage equipment, the input voltage to the detection amplifier disappears. As described above, the magnitude of the input voltage is different when the voltage of the high-voltage device is present and when the voltage is absent (or when there is a phase loss), so that three-phase power detection can be performed by one power detection amplifier.

G. Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, 1 is the A-phase main circuit conductor of the high-voltage equipment,
Reference numeral 2 is a B-phase main circuit conductor, and 3 is a C-phase main circuit conductor. 4,5,
Reference numeral 6 is a detection electrode for each phase, which is arranged so as to face the conductors 1, 2, and 3 for each phase. Reference numeral 7 is an inverting amplifier for inverting the phase of the voltage induced from the A-phase main circuit conductor 1 to the A-phase detection electrode 4 by 180 °. Reference numeral 8 denotes a detection amplifier to which the voltage induced in each of the B-phase detection electrode 5 and the C-phase detection electrode 6 and the output voltage of the inverting amplifier 7 are input. The detection amplifier 8 performs level determination to detect the presence / absence of an input voltage, and is configured as shown in FIG. 2, for example. Ie buffer 11
The AC voltage input via the rectifier 12 is rectified by the rectifier 12, and the rectified voltage and the voltage of the DC power supply 13 set to a predetermined voltage are compared by the comparator 14. The output of the comparator 14 is supplied to the transistor 17 via the resistors 15 and 16. For example, when the rectified output voltage is higher than the voltage of the DC power supply 13, the output of the comparator 14 becomes a positive level and the transistor 17 turns on. Controlled by this resistance
A current flows through the relay coil 19 via 18 and the relay output is emitted as an external output signal. When the rectified output voltage is lower than the voltage of the DC power supply 13, the output of the comparator 14 becomes a negative level and the transistor 17 is controlled to be turned off.
As a result, the relay coil 19 is in a non-excited state and no output signal is emitted.

In the device configured as described above, when the high-voltage equipment has a voltage, the vector of the detection voltage induced in the detection electrodes 4,5,6 of each phase is as shown in a, b, c of FIG. Shown in. Of the detection voltage, the voltage a induced in the A-phase detection electrode 4 has its phase inverted by 180 ° by the inverting amplifier 7, so that the output voltage a ′ of the inverting amplifier 7 and the B- and C-phase detection voltages b, The voltage vector of c is shown as in FIG. Here, the combined voltage vector of the B-phase detection voltage b and the C-phase detection voltage c has the same phase as the vector of the output voltage a ′ of the inverting amplifier 7. Therefore, the input voltage of the detection amplifier 8 in which the voltages a ', b', and c are superposed is approximately twice as large as the detection voltage of one phase, as shown by d in FIG. Therefore, if the voltage of the DC power supply 13 of the detection amplifier 8 is set to a voltage slightly lower than about twice the magnitude of the one-phase detection voltage, the output of the comparator 14 will be output when there is a three-phase voltage in the high-voltage equipment. Becomes a positive level and the transistor 17 is driven to generate an external output. Further, in the case of a phase loss accident or no voltage, the output of the comparator 14 becomes a negative level, the transistor 17 is controlled to be off, and no external output is generated. As described above, according to the configuration of FIG. 1, it is possible to easily determine the presence / absence of the three-phase voltage of the high-voltage device with one detection amplifier.

H. Effect of the Invention As described above, according to the present invention, the one in which the induced voltage phase of the detection electrode close to one conductor is inverted and the induction of each electrode close to the other two-phase conductor Since the voltage is superposed and the superposed voltage is introduced into the detection amplifier, the presence or absence of the three-phase voltage can be detected and the safety is improved.
The conventional detection amplifier can be used as it is, and the three-phase voltage can be detected by one detection amplifier. Therefore, cost reduction and space saving can be achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing an example of a detection amplifier, FIG. 3 is a three-phase detection voltage vector diagram, and FIG. 4 is an A-phase detection. A voltage vector diagram showing the relationship between the voltage obtained by reversing the voltage and the B-phase and C-phase detection voltage.
The figure is an input voltage vector diagram of the detection amplifier when there is a three-phase voltage. 1,2,3 …… A, B, C phase main circuit conductors, 4,5,6 …… A, B, C phase detection electrodes, 7 …… Inversion amplifier, 8 …… Detection amplifier, 11 …… Buffer, 12 …… Rectifier, 13 …… DC power supply, 14 …… Comparator, 15,16,18 …… Resistance, 17 …… Transistor, 19 ……
Relay coil.

Claims (1)

(57) [Claims] 1. A three-phase power detection device for a high-voltage device for detecting a voltage of a high-voltage device in which a three-phase current flows, comprising: a detection electrode provided near each phase conductor of the high-voltage device; An inverting amplifier that inverts the phase of the induced voltage of a detection electrode that is provided near one of the predetermined one-phase conductors, and each of the detection electrodes that are provided near the other two-phase conductors of the detection electrodes. An alternating voltage obtained by superposing the induced voltage of the electrodes and the output voltage of the inverting amplifier is input, and the presence or absence of the voltage of the high voltage device is determined by comparing the rectified voltage of the alternating input voltage with a predetermined set voltage. A three-phase power detection device for high-voltage equipment, comprising a power detection amplifier.