JPH0125340Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water terminal protection device for voltage testing of high voltage cables, such as OF cables.

“Figure 1” shows an outline of a conventional applied voltage test device that uses an OF cable water terminal device.

10 is OF cable.

30 is a water terminal device, which consists of a water terminal 32 and a pure water circulation circuit 60.

Reference numeral 16 designates a power source for testing, 18 designates a switch or disconnector, 20 designates a transformer, and 22 designates a protection relay (for example, a ground fault relay).

An example of the water terminal 32 is shown in "Fig. 2".

Lower metal fitting 3 fitted around cable sheath 12
4, the upper metal fitting 36 fitted around the conductor pull-out rod 14, and the insulating tube 38 form an airtight chamber 40 surrounding the cable end, and the inside is filled with cable insulating oil 42.

In addition, an insulating tube 44 is provided on the outside of the airtight chamber 46.
is formed and filled with pure water 48. In order to circulate the pure water 48, a partition wall 52 having a passage 50 above is provided in the airtight chamber 46. 54 is a pure water inlet, and 56 is an outlet.

58 indicates a thin electrode.

Further, the circulation circuit 60 includes a pure water tank 62, a pipe 6
4, a pump 66, etc.

In the test apparatus described above, when dielectric breakdown occurs in the water terminal 32 while power is being applied to the OF cable 10, the protection relay 22 immediately operates and the sheath breaker 18 opens.

However, since no special measures are taken in the circulation circuit 60, the circulation of pure water continues for a while. When the water terminal 32 causes dielectric breakdown, the cable insulating oil 42 leaks from the hole in the inner insulating tube 38 and mixes into the pure water 48. When such pure water is circulated, the entire equipment in the circulation circuit 60 and the pure water inside are eventually contaminated with oil, making it extremely difficult to reuse them.

The present invention solves the above problem, and even when the water terminal 32 has dielectric breakdown, the oil (OF
(In the case of a cable) This is to prevent it from entering the circulation circuit 60.

Embodiment As shown in FIG. 3, electromagnetic valves 68 and 70 are provided in the circulation circuit 60 near the inlet 54 and outlet 56 of pure water to the water terminal 32. These are open when energized and closed when energized.

72 is a solenoid valve 68, 70 and a pump 66
The auxiliary power supply, 74, is operated by the protection relay 22 described above.

Function When the water terminal 32 causes dielectric breakdown, the protective relay 2
2 operates, and the disconnector 18 on the test power supply 16 side
At the same time as opening, the disconnector 74 on the auxiliary power supply 72 side is opened.
Also opens.

Then, the pump 66 stops and at the same time the solenoid valve 6
8,70 closes.

Therefore, even if insulating oil leaks from the water terminal 32, the pure water in the circulation circuit 60 will not be contaminated by the solenoid valves 68 and 7.
0, and other pure water in the circulation circuit 60 is prevented from being contaminated.

Effect: At the same time as the water terminal 32 causes dielectric breakdown, the operation of the pure water circulation circuit 60 is stopped, and the solenoid valves 68 and 7
0 is closed, so the oily water terminal 3
2 is prevented from flowing into the pure water tank 62 of the circulation circuit 60.

The above is the case of the water terminal of the OF cable,
The invention can be similarly applied to water terminals of CV cables. In the case of CV cables, the terminals are in direct contact with pure water, so if dielectric breakdown occurs, there is a risk that carbonized insulators will get mixed into the pure water, but due to the same effect as above, Contamination of pure water can be prevented.

As described above, according to the device of the present invention, the pump 66
This means that the inner walls of the tank 62 and the like are not contaminated with oil, carbon, etc., and a considerable portion of the pure water can be reused without being contaminated.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the prior art, Figure 2 is an enlarged sectional view of the water terminal 32 in the case of an OF cable, and Figure 3 is an explanatory diagram of the conventional technology.
FIG. 2 is an explanatory diagram of an embodiment of the present invention in the case of an OF cable. 10: OF cable, 22: Protection relay, 3
0: Water terminal device, 32: Water terminal, 40 and 46: Airtight chamber, 42: Cable insulation oil, 48: Pure water, 5
4: Inlet, 56: Outlet, 60: Circulation circuit, 62:
Pure water tank, 66: pump, 68 and 70: solenoid valve, 74: breaker.

Claims (1)

[Claim for Utility Model Registration] A high voltage cable consisting of an airtight chamber filled with pure water surrounding the outside of the end of the high voltage cable, and a circulation circuit having a pump for circulating the pure water in the airtight chamber. In the water terminal device, a protective relay is provided that operates when the water terminal causes dielectric breakdown, and a solenoid valve is provided near the inlet and outlet of the water terminal in the circulation circuit, and when the protective relay operates, A water terminal protection device for a high-voltage cable, characterized in that, at the same time as the pump in the circulation circuit is stopped, a solenoid valve is operated to cut off the circulation circuit.