JPS60256068A - Measurement of voltage of power cable - Google Patents

Abstract

PURPOSE:To make it possible to accurately measure the charged voltage of a high voltage power cable on the way of said cable, by detecting voltage between a suspended electrode provided by peeling the shielding electrode of the power cable and the shielding electrode by a light/voltage sensor. CONSTITUTION:A part of the shielding electrode 4 of a power cable 1 is peeled off to expose an insulator 3 and a conductive or semi-conductive member is partially wound around the outer peripheral surface of said insulator 3 to form a suspended electrode 5 while a lead wire 6 is embedded in and connected to said electrode 5. Thereafter, an insulating member 7 is wound around the outer peripheries of the suspended electrode 5 and the insulator 3 to cover both outer peripheral surfaces thereof and both terminals of a shielding electrode 8 wound around the outer peripheral surface of the insulating member 7 by using a semiconductive member are wound around the outer periphery of the cable shielding layer 4 in an overlapped state to connect both shielding electrodes 4, 8. At this time, because the charging voltage of the power cable 1 is divided between lead wires 6, 9 connected to the suspended electrode 5 and the shielding electrode 8, this voltage is converted to light by a light/voltage sensor 10 while light is transmitted to a light/voltage meter 12 by an optical fiber 11 to make it possible to display voltage.

Description

Detailed Description of the Invention (1) Industrial Application Field The present invention detects the voltage of overhead cables and underground cables used as high-voltage distribution lines using optical/voltage sensors from the middle or terminal part of the cables. The present invention relates to a voltage measurement method for detection.

(2) Conventional technology Conventionally, as a measurement method for detecting the voltage applied to a live cable, there are two methods: pulling out the lead wire from the cable and detecting it using a voltage detector, or using an electric field sensor to detect the voltage applied to the outside of the cable. However, each method has the inconvenience of being able to measure only at the end of the power cable, and the work is extensive, making it difficult to measure accurately and safely. Instead, there is a desire for a method that can perform stable measurements even in the middle of the cable.

(3) Problems to be solved by the invention This invention was researched and developed in order to satisfy the above-mentioned demands, and is designed to enable stable measurement of the voltage applied to an electric power cable midway along the cable. The problem is that.

(4) Means for Solving the Problems In order to solve the above problems, the present invention partially strips off the shielding electrode on the cable insulator and injects a conductive or semi-conductive material onto the outer peripheral surface of the exposed insulator. A floating electrode using a conductive material is provided, and then the floating electrode is covered with an insulating material and a shielding material, and this shielding electrode is connected to a cable shielding electrode, and the voltage between the floating electrode and the shielding electrode is detected by a light/voltage sensor. The voltage applied to the cable conductor is measured by dividing the voltage between the cable conductor and the floating electrode and between the floating electrode and the cable shielding electrode.

(5) Embodiments Hereinafter, embodiments of the present invention will be explained based on the attached drawings.

As shown in FIG. 1, an electric power cable 1 used as a high-voltage distribution line is formed by providing an insulator 3, a shielding tape, and an external shielding electrode 4 on the outer periphery of a conductor 2.

To measure the lil voltage of cable 1,
First, a portion of the shielding layer 8i4 is peeled off over an appropriate range to expose the insulator 3.

Next, a floating electrode 5 is formed by partially winding an S conductive or semiconductive member around the outer circumferential surface of the insulator 3, and the tip of a lead wire 6 is buried and connected to the floating electrode 5 and drawn out to the outside. .

Thereafter, the insulating member 7 is wound around the outer periphery of the floating electrode 5 and the outer periphery of the insulator 3 to form a cone shape, covering both outer peripheral surfaces.

A shielding electrode 8 is formed using a semiconductive member on the outer peripheral surface of the insulating member 7.
is wound, and both ends thereof are wrapped around the outer periphery of the cable shielding layer 4, and both shielding electrodes 4 and 8 are electrically connected.

The tip of the other lead wire 9 is buried and connected to the shielding electrode 8 and pulled out to the outside, and a light/voltage sensor 1 is connected to both lead wires 6 and 9.
Connect the 0 lead wires respectively.

Note that a light/voltmeter 12 is connected to the light/voltage sensor 10 via an optical fiber 11.

Floating electrode 5 and shielding electrode 8 provided on the power cable 1
When a light/voltmeter 12 is connected to a light/voltage sensor 10, the applied voltage of the power cable 1 is divided between the lead wires 6 and 9 connected to the floating electrode 5 and the shielding electrode 8, respectively.
The voltage is converted into light by the light/voltage sensor 10 and transmitted to the light/voltmeter 12 via the optical fiber 11, so that the voltage of the electric cable 1 is displayed on the light/voltmeter 12. .

Incidentally, the specific π1 formula and the jurisdiction of each part of the above partial pressure measuring method will be explained based on the equivalent circuit shown in FIG.

Calculation formula: Here, V2 is determined by the sensitivity of the optical sensor, and if it is 200■
shall be. C3 is the distance between the conductor and the floating electrode, C2 is the ground capacitance of the floating electrode or lead wire, and 14PF is sufficient.

C3 is the capacity of the optical sensor, and if we consider a cable with a 6PF electric cable of 6.6KV 100-, the voltage division method based on the above formula is, Therefore, if we take C+ = 1 PF, we can divide the voltage. Become.

When considering the shape of the floating electrode to obtain C1 = I PF, in the above power cable, " = b
' + "F/IK-)' = t8.'o11- =
"3z("necessary"ylλ) Therefore, to obtain C+=1 PF, approximately 3 mm is sufficient.

From the above, when detecting voltage in the middle of a power cable, it is possible to easily detect the voltage by peeling off the cable shielding layer for 50 to 200 minutes and inserting a floating electrode.

(5) Effects As described above, this invention removes the shielding electrode of an electric power cable, provides a floating electrode on the outer periphery of the insulator, and connects the floating electrode with the shielding electrode provided on the outer periphery of the insulator via the insulator. Since the voltage between the two is detected using an optical/N pressure sensor,
High voltage electric cable charging 11 (4 o'7-7 lb
(7) There is an effect that accurate measurements can be made on the way.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a couple showing a state in which the present invention is implemented, and FIG. 2 is an equivalent circuit of the same. 1... Electric cable 2... Conductor 3... Insulator 4... External shielding electrode) 5... Floating electrode 6.9... Lead wire 7... Insulating member 8.
・・Shielding electrode 10 ・・Light/voltage sensor 11 ・・Optical fiber 12
...Light/Voltmeter Patent Applicant Sumitomo Electric Industries Co., Ltd. Representative Patent Attorney Kazu 1) Akira

Claims (1)

[Claims] Partially peel off the shielding electrode on the cable insulator, provide a floating electrode using a conductive or semiconductive material on the outer circumferential surface of the exposed insulator, and then cover the floating electrode with an insulating material and a shielding electrode. This shielding electrode is then connected to the cable shielding electrode, the voltage between the floating electrode and the shielding electrode is detected using a light/voltage sensor, and the voltage applied to the cable conductor is detected between the cable conductor and the floating electrode as well as between the floating electrode and the floating electrode. A method for measuring the voltage of power cables by dividing the voltage between the cable shielding electrodes.