JPS6237380Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a multi-point grounding type phase-separated gas insulated switchgear in which a sheath current is passed through the outer jacket.
In particular, the present invention relates to a phase-separated gas insulated switchgear in which a parallel conductor is provided on the outer sheath of a breaker to suppress a rise in temperature of the sheath due to sheath current.

For example, the general structure of a gas-insulated switchgear installed in a double bus line is shown in Figures 1 and 2.
It is configured as shown in the figure. In other words, 1 is a three-phase bus, 2A is a bus-side disconnector, 3 is a bridge disconnector,
2B is a line-side disconnector, 4 is a grounding device, 5 is a PD detection section, and 6 is a connection terminal device, for example, a cable head, which may be a bushing. Reference numeral 7 denotes a current transformer, 8 a connecting busbar, and the components other than the three-phase busbar 1 have a phase-separated single-phase structure, and are supported by a frame 9. The metal jacket of each device is grounded to a frame 9 at multiple points through ground wires 10, and the frame 9 is grounded to a rising ground wire 11 from a ground mesh. Then, the breaker 3 is insulated by an insulating part 13. Generally, when a phase-separated type device is grounded at multiple points, in order to prevent a large induced current from flowing through the grounding wire 10, the outer sheaths are short-circuited with an interphase shunt 12. When this is done, a sheath current i flows through the sheath of each phase via the interphase shunt 12, as shown in FIG. This current amounts to about 60% to 90% of the main circuit current, so if the outer sheath is made of steel or stainless steel with high electrical resistance, such as the sheath breaker 3, the heat generated by the sheath current will The jacket temperature increases significantly. Therefore, the current carrying capacity of the disconnector itself must be reduced. However, with this method, the switching surge that occurs when the disconnector or disconnector opens and closes is induced into the outer jacket, and this switching surge has a very high frequency, and the disconnector and other equipment are grounded. Since the insulation part 13 is different, the insulation part 13
The difference in inductance between the inductance on the disconnector side and the inductance on the other equipment side causes a potential difference in the insulating part 13, which causes air flash and deteriorates the insulator. be.

The present invention solves the above drawbacks by incorporating the sheath current circuit into the sheath current circuit without insulating the sheath breaker jacket from the jacket of other equipment, and bypassing the sheath current in the sheath breaker jacket. The present invention provides a gas insulated switchgear in which a circuit is provided to reduce the temperature rise due to the sheath current of the sheath breaker jacket itself.

In the present invention, as shown in FIGS. 3 and 4, a shunt conductor 15 is provided on the outer cover of a shunt breaker 3 forming a sheath current circuit to form a bypass circuit. The shunt conductor 15 connects a device connected to one outlet of the disconnector 3, for example, the jacket of the disconnector 2A connection, and a device connected to the other outlet, for example, the jacket of the connection of the disconnector 2B. A bypass circuit is formed for the shunt sheath and the sheath so that most of the sheath current flows through the shunt conductor 15. The rest of the configuration is the same as the conventional device shown in FIGS. 1 and 2, and the explanation thereof will be omitted. However, the circuit breaker 3 and other equipment are connected without an insulator.

In the above device, if the impedance of the jacket of the shunt breaker 3 is Zc, and the impedance of the shunt conductor 15 is Zs, the sheath current i is divided into the shunt breaker jacket and the shunt conductor as shown in Figure 5. In this case, the current ic on the shunt breaker jacket side and the current is on the shunt conductor side are expressed by the following formula.

i _c =iZ _s /Z _s +Z _c i _s =iZ _c /Z _s +Z _cIn the above equation, the electrical resistance of the sheath of the shunt breaker 3 is very high, and in comparison, the resistance of the shunt conductor 15 is Since it is very small, it generally holds that Z _s ≪Z _c . Therefore, most of the sheath current flows through the shunt conductor 15, and the current flowing through the shunt breaker jacket is reduced, making it possible to suppress the temperature rise in the jacket.

In one example test conducted on the above device, approximately 60% of the sheath current was shunted to the shunt conductor, resulting in a reduction in the sheath breaker jacket joule loss to approximately 16%.

As described above, according to the present invention, even if the sheath breaker jacket with high electrical resistance is incorporated into the sheath current circuit, its temperature rise is suppressed and the current carrying capacity is not limited, resulting in improved reliability and safety. A multi-point grounding type gas insulated switchgear with excellent performance can be provided.

[Brief explanation of the drawing]

Figures 1 and 2 are a plan view and a front view of a conventional gas insulated switchgear, Figure 3 is a front view showing an embodiment of the gas insulated switchgear according to the present invention, and Figure 4 is an explanation of the sheath current of the same device. FIG. 5 is an equivalent circuit diagram of the sheath current of the same device. 2A, 2B...Disconnector, 3...Shiya disconnector, 6...
...Cable head, 15...Shunt conductor.

Claims (1)

[Scope of utility model registration request] Each phase is equipped with a busbar-side disconnector, a line-side disconnector, a line-side disconnector, and a connecting terminal device, each containing a live part contained in an insulating gas in the outer sheath, and is configured to allow a sheath current to flow through the outer sheath. A gas insulated switchgear of a separated type, characterized in that a shunt conductor is provided in parallel with the jacket of the shunt breaker.