JPH02287166A - Insulation monitor for electric apparatus - Google Patents

Abstract

PURPOSE:To easily detect whether an apparatus is normal or defective and to impove reliability by electromagnetically coupling an antenna for check to an antenna for partial discharge detection outputting the signal from a signal source for check, and confirming the output signal of a decision device. CONSTITUTION:The antenna 10 for check is provided near the antenna 2 for partial discharge detection and both antennas are electromagnetically coupled. The antenna 10 is connected to the signal source 14 for check, whereby a signal containing frequency components of frequency band which is selected by a tuner 4 provided in the decision device 3 is outputted. When a switch 16 is turned on, a high frequency current is made to flow to the antenna 10 by the generation of the signal from the signal source 14 and the high frequency current is also made to flow to the antenna 2. When the apparatus is normal, at this time, the signal same as one at the time when the partial discharge is detected by the decision device 5 is generated, then the existence of this signal output is confirmed. With this arrangement, the normal or defective condition for the apparatus is easily detected and the reliability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an insulation monitoring device that monitors whether or not an insulation failure has occurred inside an electrical device such as a gas-insulated switchgear or a transformer.

[Prior Art] As shown in FIG. 4, this type of monitoring device includes a partial discharge detection antenna 2 placed near an electrical device 1 such as a gas-insulated switchgear or a transformer, and a The determination device 3 receives the output and determines the presence or absence of partial discharge. Although the antenna 2 is illustrated as a rod antenna in FIG. 4, this antenna is not limited to a rod antenna, and other suitable antennas such as a dipole antenna, a helical antenna, etc. may be used.

The determination device 3 includes, for example, a tuner 4 that receives the output of the antenna 2 and outputs a received signal in a predetermined frequency band, and a partial discharge occurs when the output of the tuner 4 is input and a predetermined change occurs in the input signal. The tuner 4 and the antenna 2 are connected by a coaxial cable 6.

In FIG. 4, 7 represents the power source of the electrical equipment.

When a partial discharge (corona discharge) occurs inside the container 1a of the electrical device 1 due to insulation abnormality, the surface electric field of the container 1a changes, and part of the energy of the electric field becomes electromagnetic waves and is radiated into space. Antenna 2 detects changes in this surface electric field or electromagnetic waves and provides a signal to tuner 4 . Tuner 4 is convenient for detecting partial discharge with high sensitivity.
Moreover, it is tuned to a frequency band with little external noise. When the antenna 2 detects a change in the electric field or electromagnetic waves caused by partial discharge, the state of the output signal of the tuner 4 changes. The determiner 5 detects a change in the state of this signal and generates a determination signal V indicating that a partial discharge has occurred in the electrical equipment.
Output a.

[Problems to be Solved by the Invention] The above-mentioned insulation monitoring device is a standby device that operates only when partial discharge occurs inside the electrical equipment, so if there is an abnormality in a part of the device, partial discharge may occur. Regardless of the presence or absence, the output of the determiner 5 is in a normal state (a state in which partial discharge is not detected)
will be shown.

For example, when the connection between the antenna and the coaxial cable 6 is disconnected, when the coaxial cable 6 is disconnected, when the tuner 4 is malfunctioning and cannot generate an output, or when the determiner 5 is malfunctioning. Even if a partial discharge occurs, the output of the determiner 5 will maintain the same state as when no partial discharge occurs. Conventional equipment could not easily check for these abnormalities, so
There was a possibility that the insulation monitoring device would stop working due to these abnormalities.

SUMMARY OF THE INVENTION An object of the present invention is to provide an insulation monitoring device for electrical equipment that allows easy checking of abnormalities in the device.

[Means for Solving the Problem] The first invention of the present application is a partial discharge detection antenna disposed near an electrical device, and a determination device that determines the presence or absence of a partial discharge using the output of the partial discharge detection antenna as input. The present invention relates to an insulation monitoring device for electrical equipment, which includes: a check antenna electromagnetically coupled to a partial discharge detection antenna; and a check signal that supplies a high frequency signal to the check antenna. A source was established.

The determination device is placed, for example, at a location away from the partial discharge detection antenna, and connected to the determination device by a coaxial cable for transmitting a detection signal. In this case, the check signal source is preferably placed on the check antenna side. In this case, the power terminal of the check signal source is preferably connected to a DC power source through a power supply coaxial cable.

When the determination device is placed at a location away from the partial discharge detection antenna and connected to the determination device using a coaxial cable for transmitting a detection signal as described above, the antenna is connected to the determination device by passing the antenna through the inner conductor of the coaxial cable for transmitting a detection signal. Connect to the non-grounding side signal input terminal, connect the grounding side power terminal of the check signal source to the grounding side terminal of the DC power supply through the outer conductor of the detection signal transmission coaxial cable, is preferably connected to the inner conductor of the detection signal transmission coaxial cable through a high frequency blocking coil, and the non-grounded terminal of the DC power source is preferably connected to the inner conductor of the detection signal transmission signal cable through the high frequency blocking coil.

[Function] If the check antenna is electromagnetically coupled to the partial discharge detection antenna as described above and a high frequency signal is supplied from the check signal source to the check antenna, if the device is normal, the check antenna will not be activated. When a high frequency signal is sent out from the signal source, the determination device outputs a signal similar to that when a partial discharge is detected. Therefore, it is possible to check whether the device is normal or not by applying a signal from the check signal source to the check antenna and checking the output signal of the determination device.

[Examples] Examples of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention, in which 1 is electrical equipment such as a gas-insulated switchgear or a transformer, 2 is a partial discharge detection antenna placed close to the electrical equipment 1,
3 consists of a tuner 4 and a determiner 5, and is an electrical device 1.
6 is the antenna 2, which is a determination device located at a distance from
and the determination device 3, and these are the same as conventional ones.

In the present invention, a check antenna 10 is provided near the partial discharge detection antenna 2, and both antennas are electromagnetically coupled. In the illustrated example, both antennas 2 and 10 are rod antennas, and both antennas are placed close to each other and electromagnetically coupled.

When the antenna 2.10 is constituted by a rod antenna, at least one of both antennas is covered with an insulating coating, and both antennas are tied with a cable tie 1 as shown in FIG. 3(A).
It may be made to bundle by 1st grade.

Partial discharge detection antenna 2 and checking antenna 10
may be electromagnetically coupled, and is not limited to a combination of rod antennas. For example, the antennas 2 and 10 may be formed of insulated wires, and both antennas may be bound together with a band or the like.

Further, as shown in FIG. 3(B), the pair of electric wires 12a and 12b of the parallel feeder line 12 are connected to the antennas 2 and 10, respectively.
It may also be used as

Furthermore, as shown in FIG. 3(C), the outer conductor 13a of the coaxial cable 13 is used as the partial discharge detection antenna 2,
The inner conductor 13b of the coaxial cable may be used as the antenna 10.

Furthermore, other known antennas such as dipole antennas and helical antennas may be used as the antennas 2 and 10.

The above-mentioned check antenna 10 includes a check signal source 14
is connected to the output terminal of This signal source is the determination device 3
Any signal that generates a signal including a frequency component in the frequency band selected by the tuner 4 (a signal including a harmonic component similar to the signal received by the antenna 2 when partial discharge occurs) may be used. For example, a pulse oscillator or a high-frequency oscillator using an ordinary IC may be used as this signal source, or a relay, a brushed motor, an electromagnetic bell, etc. that generate spark discharge noise at the contact point may be used to check the noise signal. It may also be supplied to the antenna for use.

A power source (a battery in this example) 15 that drives the signal source 14
is placed near the determination device 3, and the negative terminal of the power source 15 is grounded through a switch 16. power supply 15
The positive terminal of the coaxial cable 18 is connected to the inner conductor at one end of the coaxial cable 18 through the high frequency blocking coil 17, and the outer conductor of the coaxial cable is grounded.

The coaxial cable 18 extends to the vicinity of the antenna 1o, and the inner conductor at the other end of the coaxial cable is connected to the non-ground side power terminal of the signal source 14 via a high frequency blocking coil 19. The ground side power terminal of the signal source 14 is connected to the outer conductor of the coaxial cable 18.

In the above embodiment, the switch 16 is closed when inspecting the device. When the switch 16 is closed, the signal source 14 operates and generates a signal, so that a high frequency current flows through the checking antenna 10, and a high frequency current also flows through the partial discharge detection antenna 2 which is electromagnetically coupled to the checking antenna 10. . If the device is normal at this time, the determiner 5 generates the same output signal as when partial discharge is detected. Therefore, it is possible to detect whether the device is normal or not depending on whether or not this signal is output.

When the power supply 15 of the signal source 14 is placed at a location away from the signal source 14 as described above, connecting the power supply and the signal source 14 with a normal electric wire will reduce the noise generated when the power is turned on and off, and the output of the signal source. The signal leakage is the wire:! :Ride,
The wire acts as an antenna and emits electromagnetic waves. As a result, noise and leakage signals are directly applied to the coaxial cable that supplies signals to the antenna 2, making it impossible to detect a disconnection between the antenna 2 and the coaxial cable. On the other hand, if the signal source 14 and the power source 15 are connected through a coaxial cable as in the above embodiment, the above problem does not occur because signal leakage is eliminated.

In the above embodiment, the high frequency blocking coil 19 is connected to the signal source 1
This is provided to prevent signals from flowing backward from the power source 4 to the power supply side. Further, the high frequency blocking coil 17 is provided to prevent noise from entering the coaxial cable 18 side from the power source 15.

FIG. 2 shows another embodiment of the present invention. In this embodiment, the ungrounded signal source 14 is connected to the inner conductor of the coaxial cable 6 that connects the partial discharge detection antenna and the determination device 3. The side power terminal is connected through the high frequency blocking coil 19, and the ground side power terminal of the signal source is connected to the outer conductor of the coaxial cable 6. Also, the ground side terminal of the power supply 15 is grounded through the switch 16, and the coaxial cable 6
The non-grounded terminal of the power supply is connected to the inner conductor of the coaxial cable 6 through a high frequency blocking coil 17. Further, a coupling capacitor 20 for cutting direct current is inserted between the inner conductor of the coaxial cable 6 and the tuner 4.

With this configuration, only one coaxial cable is required, which simplifies the configuration and reduces costs.

In the embodiment shown in FIG. 1, the signal source 14 may be provided on the power supply 15 side (near the determination device 3), and the signal source and the antenna 10 may be connected through the coaxial cable 18. In this case, there is a possibility that a signal may leak from the signal source 14 to the tuner 4 side through the power source, and there is also a possibility that a leakage signal from the coaxial cable 18 may be transferred to the coaxial cable 6, which is not preferable.

[Effects of the Invention] As described above, according to the present invention, a check antenna is electromagnetically coupled to a partial discharge detection antenna, so that a high frequency signal can be supplied from a check signal source to the check antenna. Therefore, by emitting a signal from the check signal source and checking the output signal of the determination device, it is possible to check whether the device is normal or not, which has the advantage of increasing the reliability of the device.

In particular, according to the second aspect of the invention, the check signal source is placed on the check antenna side, the power source of the signal source is placed on the determination device side, and a coaxial cable is passed between the power source and the signal source. This eliminates the risk of the leakage signal from the check signal source getting onto the cable connecting the partial discharge detection antenna and the determination device, and ensures that the output signal from the check signal source is properly connected to the partial discharge signal source. It can be applied to the detection antenna, and the checking function can be completed.

Further, according to the invention as claimed in claim 3, since the cable connecting between the partial discharge detection antenna and the determination device is shared as the cable connecting between the check signal source and the power supply, the coaxial This has the advantage of simplifying the configuration by reducing the number of cables.

[Brief explanation of the drawing]

1 and 2 are configuration diagrams showing different embodiments of the present invention, and FIGS. 3(A) to 3C) are perspective views schematically showing different configuration examples of the antenna used in the present invention, FIG. 4 is a block diagram showing the structure of a conventional device. 1... Electrical equipment, 2... Partial discharge detection antenna,
3... Judgment device, 4... Tuner, 5... Judgment device, 6... Coaxial cable for detection signal transmission, 10... Checking antenna, 14... Checking signal source, 15
...Power supply, 17.19...High frequency blocking coil, 18
...Coaxial cable for power supply, 20...Coupling capacitor.

Claims (3)

[Claims] (1) An insulation monitoring device for electrical equipment, comprising a partial discharge detection antenna placed near the electrical equipment, and a determination device that uses the output of the partial discharge detection antenna as input to determine the presence or absence of partial discharge, An insulation monitoring device for electrical equipment, comprising: a check antenna electromagnetically coupled to the partial discharge detection antenna; and a check signal source that supplies a high frequency signal to the check antenna. (2) the determination device is disposed at a position away from the partial discharge detection antenna and connected to the determination device by a coaxial cable for transmitting a detection signal, and the check signal source is disposed on the side of the check antenna; 2. The insulation monitoring device for electrical equipment according to claim 1, wherein the power terminal of the check signal source is connected to a DC power source through a power supply coaxial cable. (3) The determination device is located at a position away from the partial discharge detection antenna, and is connected to the non-grounded side signal input terminal of the determination device through an inner conductor of a coaxial cable for transmitting a detection signal, and the check signal source is arranged on the side of the check antenna, and the ground side power terminal of the check signal source is connected to the ground side terminal of the DC power supply through the outer conductor of the detection signal transmission coaxial cable, and the ungrounded side of the check signal source The side power supply terminal is connected to the inner conductor of the detection signal transmission coaxial cable through a high frequency blocking coil, and the non-grounding side terminal of the DC power supply is connected to the inner conductor of the detection signal transmission signal cable through the high frequency blocking coil. The insulation monitoring device for electrical equipment according to claim 1, characterized in that: