JPH0447542B2 - - Google Patents

Description

[Detailed Description of the Invention] "Field of Industrial Application" The present invention relates to a method for detecting oil leakage in an OF cable,
In particular, the present invention relates to a method of detecting oil leakage based on changes in the amount of oil in a bellows type oil tank.

"Prior Art" Generally, the main part of a bellows-type oil tank attached to an OF cable is composed of a metal bellows, but even if the metal bellows has the same specifications, it is highly flexible. There are large differences in individual characteristics due to
As shown in , there is a non-linear change between the amount of oil stored and the amount of expansion/contraction displacement of the metal bellows, and the pattern of the change curve varies. cause an error.

Conventionally, one method for detecting oil leaks in OF cables is to use an oil level sensor on the metal bellows, which has the function of detecting the amount of displacement of the metal bellows part, to detect when the oil storage amount in the bellows type oil tank has decreased due to oil leakage. Some devices are attached to the tip of the device and activate an alarm when a preset value is reached. Then, multiple OFs (3, 6, etc. in the case of three-phase)
If the cables are laid in parallel,
Information from oil volume sensors installed in multiple bellows-type oil tanks is concentrated in a monitoring room at a substation, etc., and if necessary, a computer is used to collectively monitor the information. Cables can be quickly discovered and maintenance and repairs can be performed quickly.

In addition, as a method for accurately detecting changes in the amount of oil stored, it has been considered to calculate the amount of oil stored by taking into consideration factors such as the surface temperature of the OF cable, ambient temperature, and current flowing through the OF cable.

"Problems to be Solved by the Invention" However, if temperature sensors are installed depending on the difference in the OF cable installation conditions, the number of installed temperature sensors will be very large, resulting in a heavy economic burden. In addition, if the occurrence of an oil leakage accident is detected by a decrease in the amount of oil stored at the expense of economic efficiency, multiple
As the displacement pattern corresponding to the oil amount in the bellows-type oil tanks in the OF cable varies individually as explained with reference to Figure 2, it is difficult to tolerate relative errors between bellows-type oil tanks installed in parallel. As a result, oil leakage detection sensitivity is reduced, resulting in a problem that it is difficult to accurately and quickly detect the occurrence of an oil leakage accident.

The present invention solves the problems in the prior art, and provides an oil tank equipped with a bellows type oil tank.
The purpose of this system is to quickly and accurately detect the occurrence of an oil leakage accident in an OF cable, and to accurately set the initial oil storage amount in a bellows-type oil tank.

"Means for Solving Problems" The OF cable detection method according to the present invention uses actual measurement data of the amount of oil stored in a bellows-type oil tank at the time of factory shipment or at the time of on-site installation, and the amount of oil at the time of measurement of these actual measurement data. Calibration data obtained from the detection data of the sensor is stored in the control unit. Next, the detection data of the oil amount sensor obtained during OF cable operation is calibrated using the calibration data stored in the control unit and used as actual measurement data. Normally, an OF cable line consists of three lines, and an oil tank is installed for each cable line.
This system compares the measured data of each oil tank obtained by the above method, and detects that an oil leak has occurred when the range of the difference exceeds a preset value. .

"Example" First, equipment used to implement the oil leakage detection method according to the present invention will be described based on FIG. 1.

In the figure, numeral 1 is a plurality of OF cables, numeral 2 is a bellows type oil tank, numeral 3 is an oil level gauge, and numeral 4 is
Reference numeral 5 indicates an oil amount sensor, and reference numeral 5 indicates a control section.

The oil level gauge 3 is used to measure the amount of oil stored in each bellows type oil tank 2 before energizing the OF cable 1, and is used to measure the amount of oil stored in each bellows type oil tank 2 before or after connecting the bellows type oil tank 2 to the OF cable 1. It is used to find the upper and lower limits in the oil storage adjustment range, as well as to find the relative relationship between the displacement amount and oil amount (curve in Figure 2) along the way, and must be removed after actual measurement. I can do it.

Further, the measured value of the oil level gauge 3 can be directly read and input directly to the central processing unit from the input device 13 of the control section 5. Another possible method is to obtain calibration data in advance with another device when the oil tank is shipped from the factory and input it into the field-installed control device.

As shown in FIG. 1, the oil amount sensor 4 includes a pulley 6 for converting linear displacement during oil storage in the bellows type oil tank 2 into rotational motion, and a reduction gear for decelerating the rotation of the pulley 6. a mechanism 7, a potentiometer 8 driven by the reduction gear mechanism 7, and an A/D converter 9 for converting an electrical output signal (output voltage) of the potentiometer 8 into a digital signal. It is equipped with

The control unit 5 controls the signal of the oil level gauge 3 and the A/D
A central processing unit 1 receives the signal from the converter 9 and executes necessary calculations and instructions.
0 and is connected to the central processing unit 10,
Storage device 1 for storing detection data of the oil level gauge 3 and oil level sensor 4, calibration data described later, etc.
1, a display device 12 connected to the central processing unit 10 for displaying necessary information, and an input device 13 for inputting commands and various information data.
It is equipped with the following.

However, prior to the start of operation of the OF cable,
With the OF cable 1 and the bellows-type oil tank 2 separated or connected, insulating oil is fed into the bellows-type oil tank 2 to expand the metal bellows, and the amount of insulating oil (oil storage) is fed into the bellows-type oil tank 2. The oil amount) is measured by the oil amount gauge 3, and the linear displacement of the metal bellows at this time is read by the oil amount sensor 4, and these detected data are sent to the control section 5 for processing and storage. In other words, the oil amount sensor 4 obtains the actual amount of oil stored in the bellows type oil tank 2 and the displacement of the bellows portion from outside.
There is no direct proportional relationship with the measured data (output voltage of potentiometer 8, etc.), and as shown in FIG.
The corresponding oil amounts (Ya, Yb, Yc) vary depending on the individual bellows type oil tank 2, so these characteristics are stored in the storage device 11.

In addition, such characteristics (relationship between displacement amount data and measured oil amount data) may vary between the upper limit value (upper limit oil storage amount) and lower limit value (lower limit oil storage amount) of the oil storage amount, depending on the required calibration accuracy. Set the number of collections (number of divisions) of each data existing in .

Next, during OF cable operation, by activating the oil amount sensor 4, the linear displacement of the bellows type oil tank 2 is determined by the amount of rotation of the pulley 6, the output voltage of the electric potentiometer 9, and the A/D conversion. The data is transmitted to the central processing unit 10, and detection data from the oil amount sensor 4 is obtained. By using this detection data and calibration data stored in the control unit 5, the amount of oil in the bellows type oil tank 2 is converted.

In this way, the oil amount converted based on the calibration data accurately indicates the oil storage amount of the bellows-type oil tank 2, so even if there are variations in oil storage amount characteristics among the plurality of bellows-type oil tanks 2, the oil storage amount It is possible to accurately and constantly detect the upper limit, lower limit, and data on the amount of oil stored between them, and to detect the occurrence of an oil leak accident by monitoring a sudden decrease in the amount of oil within a certain period of time. I can do it.

Alternatively, when multiple OF cables 1 and bellows-type oil tanks 2 are installed in parallel, the above processing is performed for each data, and the relative difference in oil amount of multiple OF cables (for example, The difference in the amount of oil in each phase) is calculated in the control unit 5, and when the difference exceeds a preset tolerance range (threshold), an alarm is issued and the amount of oil in each phase is decreased. If there is a change, it is possible to perform oil leak detection, such as determining that an oil leak accident has occurred. In this way, multiple
Based on the relative difference in the oil amount of the OF cable,
For example, in the prior art, the linear displacement of the bellows-type oil tank 2 was detected as the oil amount, so when the data (output voltage) obtained from the oil amount sensor 4 is X, Ya, Yb, As shown by Yc, there is a difference in the true amount of oil stored, but if the calibration data is used as the standard, the relative difference will be 0 if the amount of oil stored is the same.
Therefore, an accurate comparison can be made.

Therefore, the problems in the conventional technology can be solved, and the occurrence of an oil leakage accident in an OF cable can be quickly detected with high accuracy.

In addition, as mentioned above, the setting of the initial oil storage amount range in the bellows type oil tank 2 becomes accurate,
By using the calibration data together with conditions such as the temperature of the OF cable, the ambient temperature, and the current flowing, it is possible to perform management with even higher accuracy.

"Effects of the Invention" As explained above, the OF cable oil leak detection method according to the present invention uses actual measurement data of the upper limit or lower limit of the oil storage amount and intermediate values thereof, and the oil leakage detection method at the time of measurement of these actual measurement data. Since the calibration data obtained from the detection data of the oil quantity sensor is stored and compared with the detection data of the oil quantity sensor obtained when the OF cable is energized, changes in the oil quantity of the OF cable are detected. Tolerating variations in oil storage characteristics between bellows-type oil tanks,
By constantly and accurately detecting the oil storage amount data within the oil storage amount range and monitoring a sudden decrease in the oil amount, it becomes possible to reliably detect the occurrence of an oil leakage accident.

As described above, even if only one type of oil amount sensor is used, oil leakage can be detected with high accuracy, and the configuration can be made simple.

When multiple OF cables are installed in parallel,
By calculating the relative difference between a plurality of oil amounts calculated based on calibration data, the occurrence of an oil leakage accident can be detected with high accuracy.

It has the following effects.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the OF cable oil leak detection method according to the present invention, and FIG. 2 is a relationship curve diagram between the amount of oil and the amount of displacement in a bellows type oil tank. 1...OF cable, 2...Bellows type oil tank,
3...Oil level gauge, 4...Oil level sensor, 5...Control unit, 6...Pulley, 7...Reduction gear mechanism, 8...
...Potentiometer, 9...A/D converter, 10
... Central processing unit, 11 ... Storage device, 12 ...
Display device, 13... input device.

Claims (1)

[Claims] 1. Actual measurement data of the upper limit or lower limit of oil storage amount in a bellows type oil tank and intermediate values thereof;
The calibration data obtained from the detection data of the oil quantity sensor during measurement of these actual measurement data is stored in the control unit, and the calibration data obtained from the detection data of the oil quantity sensor obtained during OF cable operation is stored in the control unit. An oil leakage detection method for an OF cable, characterized in that a change in the actual oil amount in the OF cable is detected using calibration data. 2 Calibration data obtained from the actual measurement data of the upper limit or lower limit of the oil storage amount in multiple bellows-type oil tanks and their intermediate values, and the detection data of the oil amount sensor when measuring these actual measurement data,
The oil amount sensor detection data obtained during OF cable operation and the calibration data stored in the control unit are used to store multiple data in the control unit.
A method for detecting oil leakage in an OF cable, characterized by detecting a relative difference in the amount of oil in the OF cable.