JPH07159480A - Device for monitoring insulating state of insulated synthetic resin power cable having shielding layer - Google Patents

Abstract

PURPOSE:To recognize the state of the insulator of an insulated synthetic resin power cable having a shielding layer while a voltage is applied across the cable by measuring the electric current flowing between the shielding layer and ground and eliminating unnecessary elements contained in the measured values as much as possible. CONSTITUTION:The insulating state monitoring device is constitute of a current detecting section 4 which detects the electric current flowing through a grounding cable and an arithmetic section 5. The detecting section 4 measures the electric current flowing between the grounding cable in which the individual shielding layers of a multiconductor cable (CV) are collectively formed and the ground when the grounding cable is grounded and the arithmetic section 5 recognizes the insulating state of the insulating layer by statistically processing the measured value of the electric current. In addition, the detecting section 4 uses the part of zero-potential.

Description

The present invention measures the current flowing between the shielding layer and the ground in order to know the state of the insulator during voltage application of the synthetic resin insulated power cable having the shielding layer, and the measured value In order to eliminate the unnecessary elements contained therein from the maximum, the statistical calculation process is performed to try to know the state of the insulator. As the statistical calculation method used for the experiment of this device, the “two-sided test by the central error limit” based on the normal distribution curve theory was used. Conventionally, there was no way to know the state of the insulator while the cable was in use, that is, while the voltage was being applied, but the device was complicated and expensive. At present, there is no way to know the exact state of the insulator other than measuring after a complete power failure. It is considered that there is no "safe and inexpensive" way to know the status of an insulator other than the method according to the present invention, which is the social situation where power outage work is more difficult. That is, the detection unit uses the zero potential portion.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a device in the case of a multi-core cable.

FIG. 2 is a conceptual diagram of a device in the case of a single core twisted cable.

[Explanation of symbols]

 1, core wire 2, insulator 3, shielding layer 4, current detection unit 5, calculation unit

Claims (2)

[Claims] 1. An insulation monitoring device for a multi-core synthetic resin insulated power cable. A current flowing between a grounding wire that bundles individual shielding layers of a multi-core cable (commonly called CV) and the ground when it is grounded. A device that knows the insulation state of the insulation layer by statistically processing the measured values. 2. An insulation monitoring device for a single-core twisted synthetic resin-insulated electric power cable An electric current flowing between a ground wire for grounding each shielding layer of a single-core twisted cable (common name: CVT) and the ground, and each ground wire. A device that knows the insulation state of the insulation layer by statistically calculating a total of four measured values of the current flowing between the synthetic ground wire and the ground