JPS6115660B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an end portion of an oil-insulated CV cable used in a high-voltage power transmission system, and particularly relates to a failure detection method of an insulating oil pressure compensator.

The terminals of CV cables insulated with vinyl chloride are sealed using rubber stress cones up to 154KV transmission systems, but for higher voltages of 187KV,
For 275KV systems, sealed type with oil immersion insulation or capacitor type is used. In order to improve the electrical performance of sealed terminals using oil-immersed insulation, it is necessary to pressurize the filled insulating oil. There was a lot to do. However, this requires a large amount of installation space, so in order to save space, the PT device has been built into the end of the oil-insulated CV cable.

The PT device is equipped with a metal bellows filled with inert gas under pressure in the insulating oil, which constantly applies positive pressure to the insulating oil and absorbs volume fluctuations caused by temperature changes in the CV cable insulation material, etc. This is what I did. However, there is a risk that the bellows may become fatigued during long-term use and cause gas leakage, but a reliable method for detecting such a serious failure has not yet been developed.

The present invention features a built-in PT at the end of the CV cable that can reliably detect gas leaks from the PT device.
The purpose is to provide a method for detecting equipment failure,
The feature is that it detects the amount of light reflected by the end surface of the bellows, which is transmitted through an optical fiber element installed opposite the end surface of the bellows, and issues an alarm when the amount of reflected light changes significantly by more than a predetermined percentage. It is about making it happen.

FIG. 1 is a sectional view of a CV cable terminal portion according to an embodiment of the present invention. The terminal portion of the CV cable 1 is surrounded by a post-insulator tube 4 which is electrically processed by combining a stress cone portion 2 and a capacitor 3. Further, the peripheral portion of the CV cable 1 is sealed with an end copper tube 6 and a waterproof portion 5, and is filled with insulating oil 7. This insulating oil 7 is constantly pressurized above atmospheric pressure by a PT device 8 which has an inert gas such as N ₂ sealed in a metal bellows, and the elasticity of the bellows absorbs pressure changes due to temperature changes. It compensates and maintains a constant pressure. In other words, the temperature rises and the CV cable 1
When the insulating material or the insulating oil 7 itself expands, the pressure of the sealed insulating oil 7 increases, but the volume of the metal bellows contracts accordingly to absorb the pressure increase of the insulating oil 7.

An optical fiber element 9 is installed opposite the free end surface of the bellows of the PT device 8, and this optical fiber element 9
The light generated by the light generator 10 is emitted through the light generator 10. Therefore, the reflected light from the metal end face of the bellows can be guided to the optical receiver 12 through the optical fiber element 9. Further, this optical receiver 12 is connected to an alarm device 13.

In the PT device configured in this manner, the insulating oil 7 is present between the optical fiber element 9 and the metal end face of the bellows, so even if the bellows expands and contracts, the amount of light reflected from the metal end face hardly changes. However, as shown in FIG. 2, when the metal bellows of the PT device 8 fatigue and cause gas leakage, the amount of light reflected to the optical fiber element 9 is reduced by air bubbles or the gas phase accumulated in the box 17 containing the bellows. It decreases significantly. Optical receiver 1
2 detects this change and outputs it to the alarm device 13,
cause an alarm. This makes it possible to quickly detect gas leakage from the bellows and take countermeasures.

FIG. 3 is an enlarged sectional view of the main part of FIG. 2, in which a transparent cap 15 made of glass is attached to the tip of the optical fiber element 9 and sealed with a seal portion 16. For convenience of illustration, the optical fiber element 9 is shown horizontally, but when the PT device 8 is installed vertically, gas leaking from the bellows will accumulate in the upper part of the box 17 where the optical fiber element 9 is installed. , it becomes easy to detect gas leaks.

The failure detection method of the PT device of this example is to install an optical fiber element opposite the end face of the bellows in a box containing a bellows that acts as if the sealed insulating oil is under constant positive pressure. By constantly monitoring the bellows, gas leakage from the bellows can be reliably detected. By this,
Reliably detects gas leak failures in PT equipment to improve reliability and prevent oil insulation before serious failures occur.
The effect is that the CV cable power transmission system can be easily maintained.

The failure detection method for a PT device built into the terminal portion of a CV cable according to the present invention has the effect of reliably detecting gas leakage from the bellows of the PT device and improving the reliability of the PT device.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a CV cable terminal part according to an embodiment of the present invention, Fig. 2 is a cross-sectional view of the PT device shown in Fig. 1, and Fig. 3 is an enlarged cross-sectional view of the optical fiber element shown in Fig. 2. be. 1...CV cable, 7...Insulating oil, 8...Pressure compensation device (PT device), 9...Optical fiber element,
10... Light generator, 11... Optical fiber cable, 12... Optical receiver, 13... Alarm device, 14
... Bellow end face, 15 ... Cap, 17 ...
box.

Claims (1)

[Claims] 1. In a pressure compensator that installs a metal bellow in which an inert gas is sealed in insulating oil at a pressure higher than atmospheric pressure in the terminal part of an oil-insulated CV cable, a A pressure compensator built into the end of the CV cable, which detects the amount of light reflected by the end face of the bellows and generates an alarm when the amount of reflected light changes significantly by more than a predetermined percentage. Fault detection method.