JPH01164219A - Oil leak detection of oil-field cable - Google Patents

Abstract

PURPOSE:To detect oil leak at a stage where leaked oil is in a corrosion-proof layer and not yet flowed out to the outside, by fixing a distorsion gauge directly onto the corrosion-proof layer at a position in an OF (oil field) cable line where oil may leak or by winding a tape fixed with a distorsion gauge around the corrosion-proof layer thereby detecting oil leak based on distorsion detected through the distorsion gauge. CONSTITUTION:A copper joint pipe 11 containing the joint of a cable core and the metal sheathe of a cable 2 are jointed air-tightly through a lead work section 12 onto which a lead work section corrosion-proof layer 13 is applied from the corrosion-proof layer 11a of the joint copper pipe 11 to the corrosion- proof layer 2a of the OF cable 2. A metal tape 1 having upper face fixed with a distorsion gauge is wound around the corrosion-proof layer 13. Output from the distorsion gauge is monitored continuously, and it is judged to be slight oil leak if distorsion of the metal tape 1 increases regardless of ambient tempera ture or load current of cable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an oil leak detection method for early detection of oil leaks in OF cables.

(Prior art and problems to be solved) The Nogaura points of the OF cable are the connecting steel pipe of the cable connection part and the leadwork part of the metal sheath of the cable, the vicinity of the conduit entrance of the conduit installation cable,
There is a high probability that this occurs in areas such as cleats, but in the past most cases were discovered only after it leaked from the anti-corrosion layer in these areas, and oil leak detection sensors were also used that came into direct contact with oil. was.

However, if oil lags from the OF cable and flows into manholes or tunnels, it becomes a difficult task to dispose of the oil afterwards, and if there is a large amount of oil leaking, it can cause problems in cable operation. was there.

(Means for Solving the Problems) The present invention solves the above-mentioned problems and provides an oil leak detection method that detects oil leaks when they are within the corrosion protection layer and have not yet flowed outside. The feature is that a strain gauge is installed directly on the anticorrosion layer at a point where oil leakage may occur in the OF cable line, or a tape with the strain gauge attached is wrapped around it, and the strain generated on the tape prevents oil from leaking. The purpose is to detect.

FIG. 1 is an explanatory diagram of an example in which the oil leakage detection method of the present invention is applied to an OF cable near a pipe entrance. In the drawing, (1
) is a metal tape wrapped around an OF cable (2) having a corrosion protection layer near the pipe entrance, and a strain gauge (10) is attached to its upper surface as shown in No. 3-. (3) is the cable conduit, (4) is the conduit mouth waterproof gi? Z% (5) is a manhole.

FIG. 2 is an explanatory diagram of an example in which the oil leakage detection method of the present invention is applied to a connecting steel pipe of a cable connection part and a leadwork part of a metal sheath of a cable. The connecting steel pipe (11) containing the connection part of the cable core and the metal sheath of the cable (2) are airtightly connected by a lead part (I2), and on the lead part (12) there is a Corrosion protection layer (11t) of connecting steel pipe (11)
A leadwork corrosion protection layer (I3) is applied from above Ll to above the corrosion protection layer (2tL) of the OF cable (2). A metal tape 0) having a strain gauge (10) attached to its upper surface is wound on the leadwork part corrosion protection layer 03).

Therefore, in the above-mentioned Figures 1 and 2, the output of the strain gauge (I0) is continuously monitored, and the strain value of the metal tape (1) tends to increase regardless of the ambient temperature or the load current of the cable. If this occurs, it is determined that there is a slight oil leak.

The metal tape (1) to be wrapped around the anti-corrosion layer must fit the anti-corrosion layer sufficiently and be thick enough to cause distortion when oil leaks into the anti-corrosion layer and internal pressure increases. do.

According to the oil leakage detection method of the present invention described above, a metal tape equipped with a strain gauge is wrapped around the anticorrosive layer, and the elongation of the metal tape due to internal pressure is detected using the strain gauge. but,
Since the distortion rate is not very large and the output is therefore small, an amplifier is installed nearby as shown in FIG. in this case,
When the distance between the amplifier and the speed recorder is long, using a metal wire will reduce detection accuracy due to induction from the power cable, so it is recommended to incorporate an E10 converter inside the amplifier and transmit the speed recorder signal using an optical cable. is preferred.

In addition, since the metal tape is heated by the load current of the cable and becomes distorted, it is preferable to compare the changes in the distortion of the three phases of the cable to determine whether there is an oil leak.

According to the report, oil leaks from the cable's metal sheath or lead work at connections can be detected before they leak outside through the anti-corrosion layer. This eliminates the need for a lot of work, and the labor-saving effect is significant.

Also, large oil leaks can be prevented. In other words, if the oil leakage from the metal sheath or leadwork part is in a state where the corrosion protection layer swells and does not leak to the outside, the amount of oil leakage from the cable system itself is small, but the corrosion protection layer will no longer be able to withstand it. Once the anti-corrosion layer is destroyed, the amount of oil leaking increases rapidly and becomes a large oil leak.
This may cause problems such as interfering with cable operation, but the present invention can prevent such large oil leaks and eliminate operational problems through early detection.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an example in which the method for detecting maroon oil of the present invention is applied to an OF cable near a pipe entrance. FIG. 2 is an explanatory diagram of an example in which the oil leak detection method of the present invention is applied to a leadwork part of a cable connection part. FIG. 3 is an explanatory diagram of a circuit that sends a metal tape distortion signal to a recorder. ■...Metal tape, 2...OF cable, 2a...
・Cable anti-corrosion layer, 3... Conduit, 4... Conduit mouth waterproofing device, 5... Manhole, IO... Strain gauge, ll
... Connecting steel pipe, 12-... Lead work part, 13... Lead work part anti-corrosion layer.

Claims (2)

[Claims] (1) Install a strain gauge on the anti-corrosion layer at a point where oil leakage may occur in the OF cable line. An oil leakage detection method for an OF cable, characterized in that oil leakage is detected by strain generated in a tape. (2) The OF cable oil leakage detection method according to claim 1, wherein the output of a strain gauge is continuously monitored, and oil leakage is detected based on an abnormal increase in strain.