JPS636698Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for electrically checking the insulation quality of an electrically insulating section such as an insulating flange of a gas insulated switchgear.

In recent years, due to the increase in power demand, the increase in capacity, the difficulty in securing land, and the need for environmental measures have led to the need for smaller volumes, high safety against electric shocks, explosions, fires, etc., and resistance to negative influences from the outside world such as salt dust damage and flooding. Gas-insulated switchgear, which has features such as being resistant to electrical shock, has become widely installed in power generation and substations. Gas-insulated switchgear has a live part inside a metal container, and the container is filled with an insulating gas such as sulfur hexafluoride (SF ₆ ) instead of air. It is composed of a combination of a grounding device, a ground bus, a bus, and an earth protector. A schematic side view of an assembly of an example of this gas insulated switchgear is shown in FIG. In the figure, reference numeral 1 denotes a power receiving bushing, which draws extra high power from an overhead wire or the like (not shown). This power receiving bushing 1 has one side insulated in air and the other side insulated in SF ₆ gas. 2 is a grounding device, which allows the power receiving point to be safely grounded if necessary. 3 is a power receiving disconnector which disconnects the received power as necessary. 4
Reference numerals a and 4b refer to connection busbars, and reference numeral 5 indicates a power receiving shield switch for switching on/off, cutting off, and supplying received power. 6a, 6b
is a busbar branch disconnector that can disconnect each busbar as necessary. 7a and 7b are feeder busbars (not shown). 8 is an earth protector that safely discharges abnormal voltage to protect equipment. Reference numerals 9a and 9b indicate through-type current transformers for measuring circuit current, which are attached to the outer periphery of the container of the gas-insulated switchgear at the opening of the power receiving shield breaker 5.
10a and 10b are insulating sections. The reason for providing this insulating section is as follows. In other words, this type of gas-insulated switchgear generally prevents surges propagating to the low-voltage control circuit when switching devices such as the grounding device 2, the power receiving disconnector 3, the branch disconnectors 6a and 6b, and the power receiving disconnector 5 open and close. Multi-point grounding may be used to reduce the level and prevent the structure from overheating due to induced current in the container. In such a case, the container and the ground constitute a closed circuit, and the feedthrough current transformers 9a and 9b pass through the closed circuit, making it impossible to accurately measure the circuit current. Therefore, insulating sections 10a, 10b are provided to open the closed circuit. The details of the insulating sections 10a, 10b are as shown in a detailed partially sectional view of FIG. The containers of the gas insulated switchgear are connected to each other by flanges, and in FIG. 2, the respective flanges are indicated by 11a and 11b. An insulating spacer 12 is inserted between the flanges 11a and 11b, and insulates and supports a conductor inside the container (not shown). A peripheral portion of the insulating spacer 12, that is, a flange portion 12a corresponding to the flanges 11a and 11b is made of metal due to the need for mechanical strength. Both flanges 11a, 11b
The flange portion 12a of the insulating spacer 12 is tightened with a plurality of circumferential through bolts 13 and nuts 13a. Either one of the tightening parts, the flange 11a side in the figure, is insulated. Specifically, insulation is provided by an insulating ring 14, an insulating tube 15, and an insulating washer 16, a washer 17 is placed on the insulating washer 16, and a spring washer 18 is further placed on top of the insulating washer 16 to prevent loosening, and then tightened with a nut 13a. The issue here is whether the flange portion 12a of the insulating spacer 12 and the flange 11a of one of the containers are reliably insulated. For example, if the insulating washer 16 and the insulating washer 17 are installed in the wrong order and are installed in the opposite direction in the fully assembled state, the flange portion 12a of the insulating spacer 12
and the flange 11a of the container are no longer insulated.
A detailed partial cross-sectional view in that case is shown in FIG. Since the parts are exactly the same as those in FIG. 2, the same parts are given the same reference numerals and their explanation will be omitted. In addition, the insulation may be damaged due to adhesion of conductive dust to the flange portion. When this happens, the through-type current transformer 9a,
9b passes through the closed circuit consisting of the container and the ground circuit as described above, making it impossible to accurately measure the main circuit current. At this point, it is difficult to diagnose from the outside whether the insulation of the flange of the container is reliable. For example, even if a meter such as a tester or a megger is used, since the container is grounded at multiple points, their grounding resistance is lower than the insulation resistance of the flange, and both indicate a conductive state. In order to confirm this, the grounding circuit must be disconnected and the entire gas-insulated switchgear must be ungrounded, which is difficult work and cannot be done while power is being applied.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a device for electrically checking the insulation state of an insulating section of a gas-insulated switchgear in the fully assembled state.

Hereinafter, an embodiment of the insulation checking device for the insulation section according to the present invention will be described in detail with reference to FIG. In the figure, 10a is the insulating section described in FIG. 1, and the details of its structure are the same as described in FIG. 2, so the explanation will be omitted. Lead wires 19a and 19b of the insulation checking device 20 are connected to ground wire connection terminals (not shown) of the container on both sides of the insulation section 10a. On the other hand, the container is grounded at multiple points, and its equivalent impedances Z _0a and Z _0b form a grounding circuit. A block diagram of the internal circuit of the insulation checking device 20 for the insulation section is shown in FIG. In the figure, reference numeral 20a denotes a power supply circuit section, which is, for example, a portable power supply such as a battery. Reference numeral 20b denotes a pulse generation output section which receives constant voltage from the power supply circuit section 20a, converts it into pulses, and transmits the pulse current from the input/output terminal 20c through the lead wires 19a and 19b explained in FIG. 4 to the insulated section. output to both ends of the section. The amplifying part 20d detects a voltage drop caused by the pulse current in proportion to the impedance at both ends of the insulation section, which will be explained later.
The signal is detected, amplified, and output to the comparison/difference signal output section 20e at the next stage. The comparison/difference signal output section 20e compares this signal with a constant voltage signal supplied from the power supply circuit section 20a, and outputs the difference voltage to the display section 20f. This display section displays the differential voltage on an analog or digital display. All of these parts are put together in one storage box, making it portable. The principle and operation of this insulation checking device 20 will be explained as follows with reference to FIGS. 6a and 6b. That is, in Fig. 6a, _Z1 is the equivalent impedance of the multi-point grounding circuit including the frame of the gas insulated switchgear as seen from the input/output terminal 20c of the device, and the voltage drop when the pulse current is passed through it is _V1 . do.
Similarly, in FIG. 6b, Z ₂ is the equivalent impedance of the insulating section when it is conducting, and the voltage drop is V ₂ . Generally, the relationship between both impedances is Z ₁ ≫Z ₂ , so naturally V ₁ ≫V ₂ . Therefore, if the signal from the power supply circuit section 20a to the comparison/difference signal output section 20e of the insulation confirmation device 20 is adjusted to be almost the same as _V1 , the display device 20f will be displayed when the insulation section is normally insulated. There is no display, but if the insulation section is conductive, a display will appear, indicating an abnormality in the insulation.

According to the present invention described above, the quality of the insulation of the insulating section of a gas-insulated switchgear or the like can be easily checked by a single measuring person without disconnecting the multi-point grounding circuit.

The device of the present invention can be applied not only to the insulating sections of gas-insulated switchgear, but also to checking the quality of various insulating sections, such as insulating flanges for preventing shaft currents of rotating machines.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view of an assembly of an example of a gas insulated switchgear to which the device of the present invention is applied, and Fig. 2 is a detailed partial cross-sectional view of an insulating section of the gas insulated switchgear shown in Fig. 1.
Fig. 3 is a detailed cross-sectional view of the same part as Fig. 2 in the case of incorrect assembly, Fig. 4 is a schematic connection diagram of an embodiment of the insulation checking device for an insulating section according to the present invention applied to a gas insulating device, and Fig. 5 The figure is also a block diagram of the internal circuit of the insulation confirmation device, and Figures 6a and 6b are equivalent impedance circuit diagrams of the multi-point grounding circuit including the frame of the gas insulated switchgear as seen from the output terminal of this device. . 1...Power receiving bushing, 2...Grounding device, 3...
...Power receiving disconnector, 4a, 4b... Connection bus bar, 5...
...Power receiving circuit breaker, 6a, 6b...Bus bar branch disconnector, 7a, 7b...Bus bar, 8...Surge arrester, 9
a, 9b...Feedthrough current transformer for measuring circuit current, 10
a, 10b... Insulating section, 11a, 11b...
Flange of each container, 12...Insulating spacer, 12
a... Flange portion of insulating spacer, 13... Through bolt, 13a... Nut, 14... Insulating ring, 15... Insulating tube, 16... Insulating washer, 17
...Washiya, 18...Spring Wasiya, 19
a, 19b...Lead wire of insulation confirmation device, 20...
...Insulation confirmation device, 20a...Power circuit section, 20b
...Pulse generation output section, 20c...Input/output terminal,
20d...Detection amplification unit, 20e...Comparison/difference signal output unit, 20f...Display unit.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A power supply circuit section, a generation output section that converts the output from the power supply circuit section and generates a signal current, and both ends of an insulating section of a device whose both ends are grounded. A detection amplifier section sends out the signal current from the generation output section, detects the voltage drop generated in proportion to its impedance, and amplifies the signal, and compares the output signal from the detection amplifier section with a reference signal. An insulation device comprising: a comparison/difference signal output section that outputs a difference signal; and a display section that displays the difference signal from the comparison/difference signal output section to check whether the insulation of the insulation section is good or bad. Insulation confirmation device for division section. (2) Utility model registration claim No. (1) characterized in that the generation output section converts the output from the power supply circuit section into pulses and outputs a pulse signal current.
Insulation confirmation device for the insulation section described in Section 1.