JPH0734028B2 - Insulation monitoring device for electrical equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an insulation monitoring device for monitoring whether or not insulation failure has occurred inside an electric device such as a gas-insulated switchgear or a transformer.

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

The determination device 3 receives, for example, 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 used as an input and a predetermined change occurs in the input signal. The partial discharge judging device 5 which outputs a judgment signal Va indicating that
The antenna 2 and the antenna 2 are connected by a coaxial cable 6.

Incidentally, in FIG. 4, reference numeral 7 represents a power source of electric equipment.

When a partial discharge (corona discharge) occurs inside the container 1a of the electric device 1 due to insulation abnormality, the surface electric field of the container 1a changes, and a part of the energy of the electric field is radiated as an electromagnetic wave into the space. The antenna 2 detects the change in the surface electric field or the electromagnetic wave and gives a signal to the tuner 4. Tuner 4
Is suitable for detecting partial discharge with high sensitivity, and is tuned to a frequency band with less external noise. When the antenna 2 detects the change in the electric field or the electromagnetic wave caused by the partial discharge, the state of the output signal of the tuner 4 changes. The judging device 5 detects the change of state of this signal,
A determination signal Va indicating that partial discharge has occurred in the electric device is output.

[Problems to be Solved by the Invention] The above-described insulation monitoring device is a standby type device that operates only after partial discharge occurs in an electric device. Therefore, if a part of the device is abnormal, the partial discharge Regardless of whether it is present or not, the output of the determiner 5 is normal (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 fails and cannot output, or when the determiner 5 fails. Even if the partial discharge is generated, the output of the determiner 5 maintains the same state as when the partial discharge is not generated. In the conventional device, since these abnormalities could not be easily checked, there is a possibility that the insulation monitoring device may not operate due to these abnormalities.

It is an object of the present invention to provide an insulation monitoring device for electric equipment, which can easily check the abnormality of the device.

[Means for Solving the Problem] A first invention of the present application is a determination device for determining the presence or absence of partial discharge by using an antenna for partial discharge detection arranged near an electric device and an output of the antenna for partial discharge detection as inputs. In the present invention, a check antenna electromagnetically coupled to a partial discharge detection antenna and a check signal for supplying a high frequency signal to the check antenna are provided. And the source.

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

When the determination device is arranged at a position distant from the partial discharge detection antenna as described above and is connected to the determination device by the detection signal transmission coaxial cable, the antenna is passed through the inner conductor of the detection signal transmission coaxial cable. Connect to the ground-side signal input terminal, connect the ground-side power terminal of the check signal source to the ground-side terminal of the DC power supply through the outer conductor of the detection signal transmission coaxial cable, and connect the ground-side power terminal of the check signal source Is preferably connected to the inner conductor of the detection signal transmission coaxial cable through a high frequency blocking coil, and the non-grounded 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.

[Operation] When 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 When the high frequency signal is sent from the signal source, the same signal as when the determination device detects partial discharge is output. Therefore, it is possible to check whether or not the device is normal by applying a signal from the checking signal source to the checking antenna and checking the output signal of the determination device.

Embodiments Embodiments 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 an electric device such as a gas-insulated switchgear or a transformer, 2 is an antenna for detecting partial discharge, which is arranged close to the electric device 1,
Reference numeral 3 denotes an electric device 1 including a tuner 4 and a judging device 5.
The determination device 6 disposed at a position away from the antenna 2 is an antenna 2
And the determination device 3 are coaxial cables, which are the same as conventional ones.

In the present invention, the checking antenna 10 is provided in the vicinity of the partial discharge detection antenna 2, and both antennas are electromagnetically coupled. In the illustrated example, the antennas 2 and 10
Are both rod antennas, and both antennas are closely arranged and electromagnetically coupled.

When the antennas 2 and 10 are constituted by rod antennas, at least one of the two antennas may be covered with an insulating coating, and both antennas may be bound by a binding band 11 or the like as shown in FIG. 3 (A).

The partial discharge detection antenna 2 and the check antenna 10 need only be electromagnetically coupled, and are not limited to the combination of rod antennas. For example, the antennas 2 and 10 may be formed by insulating coated electric wires, and both antennas may be bound by a band or the like.

Further, as shown in FIG. 3B, the electric wires 12a and 12b of the pair of parallel feeder wires 12 may be used as the antennas 2 and 10, respectively.

Further, as shown in FIG. 3C, the outer conductor 13a of the coaxial cable 13 may be used as the partial discharge detection antenna 2, and the inner conductor 13b of the coaxial cable may be used as the antenna 10.

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

The checking antenna 10 is connected to the output terminal of the checking signal source 14. As long as this signal source generates a signal including a frequency component of a frequency band selected by the tuner 4 in the determination device 3 (a signal including a harmonic component similar to the signal received by the antenna 2 when a partial discharge occurs). Good. For example, a pulse oscillator or a high-frequency oscillator using an ordinary IC may be used as the signal source, a relay,
The noise signal may be supplied to the checking antenna using a brush motor, an electromagnetic bell, or the like that causes spark discharge noise at the contact.

A power supply (battery in this example) 15 for driving the signal source 14 is arranged near the determination device 3, and a negative terminal of the power supply 15 is grounded through a switch 16. The positive terminal of the power supply 15 is connected to the inner conductor on one end side 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 10, and the inner conductor on the other end side of the coaxial cable 18 has a high frequency blocking coil 19
Is connected to the non-grounded power supply terminal of the signal source 14 via. The ground side power supply 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 to inspect the device. When the switch 16 is closed, the signal source 14 operates to generate 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 electromagnetically coupled to the checking antenna 10. . At this time, if the device is normal, the determiner 5 generates an output signal similar to that when the partial discharge is detected. Therefore, whether or not the device is normal can be detected by the presence or absence of the output of this signal.

When arranging the power source 15 of the signal source 14 at a position distant from the signal source 14 as described above, connecting the power source and the signal source 14 with a normal electric wire causes noise generated at power on / off and output of the signal source. The leaked signal travels on the electric wire, and the electric wire serves as an antenna to emit an electromagnetic wave. As a result, noise or a leak signal is directly applied to the coaxial cable that supplies the signal to the antenna 2, and it becomes impossible to detect the disconnection between the antenna 2 and the coaxial cable. On the other hand, when the signal source 14 and the power source 15 are connected through the coaxial cable as in the above-described embodiment, signal leakage is eliminated, so that the above problem does not occur.

In the above embodiment, the high frequency blocking coil 19 is provided to prevent a signal from flowing backward from the signal source 14 to the power supply side. The high frequency blocking coil 17 is provided to prevent noise from entering from the power supply 15 to the coaxial cable 18 side.

FIG. 2 shows another embodiment of the present invention. In this embodiment, the signal source 14 is not grounded to the inner conductor of the coaxial cable 6 that connects the partial discharge detection antenna and the determination device 3. The side power supply terminal is connected through the high frequency blocking coil 19, and the ground side power supply 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 a switch.
It is grounded through 16 and is connected to the outer conductor of the coaxial cable 6, and the non-grounded side terminal of the power source is connected to the inner conductor of the coaxial cable 6 through the high frequency blocking coil 17. A coupling capacitor 20 for cutting direct current is inserted between the inner conductor of the coaxial cable 6 and the tuner 4.

According to this structure, since only one coaxial cable needs to be provided, the structure is simplified and the cost can be reduced.

In the embodiment of FIG. 1, it is considered that the signal source 14 is provided on the power source 15 side (in the vicinity of the determination device 3) and the signal source and the antenna 10 are connected through the coaxial cable 18, but In this case, there is a possibility that the signal may sneak into the tuner 4 side from the signal source 14 through the power source,
In addition, a leak signal from the coaxial cable 18 may get on the coaxial cable 6, which is not preferable.

As described above, according to the present invention, the checking antenna is electromagnetically coupled to the partial discharge detecting antenna so that a high-frequency signal can be supplied from the checking signal source to the checking antenna. Therefore, it is possible to check whether or not the device is normal by outputting a signal from the checking signal source and checking the output signal of the determination device, and there is an advantage that the reliability of the device can be improved.

In particular, according to the invention described in claim 2, the check signal source is arranged on the check antenna side, the power source of the signal source is arranged on the determination device side, and the coaxial cable is provided between the power source and the signal source. Since the connection is made possible, there is no risk that the leak signal of the checking signal source will get on the cable connecting the partial discharge detection antenna and the judgment device, and the output signal of the checking signal source can be reliably detected. It can be given to the antenna, and the check function can be perfected.

Further, according to the invention described 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 There is an advantage that the number of cables can be reduced and the configuration can be simplified.

[Brief description of drawings]

1 and 2 are configuration diagrams showing different embodiments of the present invention, and FIGS. 3 (A) to 3 (C) are perspective views schematically showing different configuration examples of an antenna used in the present invention, FIG. 4 is a configuration diagram showing a configuration of a conventional device. 1 ... Electrical equipment, 2 ... Partial discharge detection antenna, 3 ...
・ ・ ・ Judgment device, 4 ・ ・ ・ Tuner, 5 ・ ・ ・ Judgment device, 6 …… Coaxial cable for transmitting detection signal, 10 …… Check antenna, 14 …… Check 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 apparatus for an electric device, comprising: an antenna for detecting a partial discharge arranged in the vicinity of the electric device; and a judging device for judging the presence or absence of a partial discharge by using an output of the antenna for detecting the partial discharge as an input. 2. An insulation monitoring apparatus for electric 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 arranged at a position apart from the partial discharge detection antenna and connected to the determination device by a detection signal transmission coaxial cable, and the check signal source is arranged on the check antenna side. The insulation monitoring apparatus for electric equipment according to claim 1, wherein the power source terminal of the checking signal source is connected to a DC power source through a power supply coaxial cable. 3. The checking device is arranged at a position distant from the partial discharge detecting antenna and is connected to a non-ground signal input terminal of the judging device through an inner conductor of a detection signal transmitting coaxial cable, A signal source is arranged on the side of the check antenna, a ground side power supply terminal of the check signal source is connected to a ground side terminal of a DC power supply through an outer conductor of the detection signal transmission coaxial cable, The non-grounded 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 a high frequency blocking coil. The insulation monitoring device for an electric device according to claim 1, wherein