JP3065815B2 - Partial discharge detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a partial discharge detection method for detecting the presence or absence of a partial discharge at an insulated connection portion of a power cable at the time of completion of construction work of a power cable or the like.

[0002]

2. Description of the Related Art Conventionally, as a method for detecting a partial discharge of an insulated connection portion of a power cable, two foil electrodes J and K are attached to the insulated connection portion as shown in FIG. It is known that a detection impedance Z is connected therebetween to detect a signal induced in a coil and to detect the presence or absence of a discharge near an insulated connection.

[0003]

However, in this method, it is often very difficult to discriminate the actual partial discharge from the noise because the noise mixed in the cable and the foil electrode is also detected.

An object of the present invention is to provide a partial discharge detection method for detecting only a partial discharge signal by removing noise mixed in a cable and a foil electrode.

[0005]

According to the present invention, there is provided a method for detecting a partial discharge, comprising the steps of: connecting an electrode to each insulated connecting portion of a two-phase power cable; The electrodes are connected to each other via a load, and a signal between the in-phase cables from the electrodes obtained by the load is differentially detected. The differential processing detects the partial discharge in the vicinity of the insulated connection by canceling noise in the signal by the differential processing.

[0006]

The partial discharge detection method having the above-described configuration is capable of effectively removing noise by differentially connecting signals between in-phase power cables and signals between out-of-phase power cables to thereby reduce a partial discharge signal. Extract only

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a circuit configuration diagram for implementing the method according to the present invention. The conductors of the arbitrary two-phase cables 1 and 2 of the polyphase AC line are connected to each other, and at the insulation connection part where the connection between the shields is not made, a foil is attached to each insulation connection terminal 1a, 1b, 2a, 2b. Electrodes 3a, 3b,
4a and 4b are attached and connected via the detection coils 5 and 6 for each phase. Then, secondary coils 5 'and 6' are combined with these detection coils 5 and 6, and the secondary coils 5 'and 6' are connected to polarities such that outputs from the detection coils 5 and 6 cancel each other. And this is another coil 7, 7 '
To the measuring instrument 8 via

Thus, even if a partial discharge occurs in the vicinity of any of the insulated connection terminals 1a, 1b, 2a, 2b, the foil electrode 3 can be regarded as a capacitor.
The signals will be detected by the measuring device 8 via a, 3b, 4a, 4b and the detection coils 5, 6, etc. However, since noise is considered to be similarly mixed into the insulators of the cables 1 and 2 from an external noise source, these noises are insulated at the coils 5 and 5 'by the insulated connection terminal 1a,
1b and the insulated connection 2 in the coils 6, 6 '
a, 2b offset by the differential insulation between the two, and subsequently by the differential connection of the cables 1, 2 in the coils 7, 7 ', and the measuring device 8 has an insulation connection terminal 1
Only signals due to discharges near a, 1b, 2a, and 2b are obtained.

The detected partial discharge is caused by any cable 1,
Although it is difficult to immediately determine which of the two insulators is caused, it is possible to estimate which insulator is caused by combining with the remaining one-phase power cable.

FIG. 2 is an explanatory view of detecting and managing the partial discharge of the three-phase cables A, B, and C at one place by using the method according to the present invention. The electrode 14 is selected by a switch 15 and an arbitrary two-phase cable is combined. The output of the switch 15 is connected to a signal processing circuit 16 containing a primary coil, a secondary coil, and the like. The signal from the foil electrode 14 is differentially detected by the method in the embodiment, and guided to the measuring device 17.

Therefore, by switching the switch 15 by remote control or the like using a signal line (not shown), a signal between any of the foil electrodes 14 can be sequentially obtained by the measuring device 17, and any cable is connected at each connection portion. It is possible to detect whether there is a partial discharge in A, B, and C.

[0012]

As described above, the method for detecting partial discharge according to the present invention can sufficiently remove noise in the insulator by differential connection between in-phase and out-of-phase, so that the partial discharge signal is detected. Measurement can be performed with high sensitivity.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram for implementing the present invention.

FIG. 2 is an explanatory diagram of a discharge detection management system.

FIG. 3 is an explanatory diagram of a conventional partial discharge detection method.

[Explanation of symbols]

 1, 2, A, B, C Cable 1a, 1b, 2a, 2b Connection terminal 3a, 3b, 4a, 4b, 14 Foil electrode 5, 6 Detection coil 5 ', 6' Secondary coil 7, 7 'Coil 8 , 17 Measuring device 15 Switching device 16 Signal processing circuit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01R 31/12

Claims (1)

(57) [Claims] 1. An insulated connection of a multi-phase power cable, wherein electrodes are attached to respective insulated connections of a two-phase power cable, and these electrodes are connected to each other via a load;
A difference between the in-phase cables obtained by differentially detecting a signal between the in-phase cables from the electrodes obtained by the load.
The dynamic signal Oite difference dynamically detected between different phase cable, which
A partial discharge near the insulated connection is detected by canceling noise in the signal by the differential processing.