JPH0266471A - Loading test device - Google Patents

Abstract

PURPOSE:To accurately find out the defective position of a sample by forming a partial discharge detecting part and an accumulated electrostatic energy discharging/ removing circuit on the sample connected to the secondary side of a transformer and arranging three or more partial discharge generating source position standardizing detectors. CONSTITUTION:The voltage of an AC commercial power supply 1 is boosted by a transformer 2 and a high voltage is impressed from terminals 6a, 6b to the sample A. Electrostatic energy is accumulated in the sample A, partial discharge of various sizes is generated and pulses are generated. The charged quantity of the partial discharge is detected by a discharge detecting part 8 as a voltage value through a capacitor 7, and when the detected value reaches a prescribed value, the signal is inputted to a signal generating part 9, logical operation is executed and control signals 91, 95 are outputted. The signal 91 closes an energy discharging/removing circuit 10 to execute discharge. The signal 95 opens a breaking circuit 5. Three position standardizing detectors 11a to 11c fixed to the sample A detect and record ultrasonic waves generated from a discharge generating source and computes 14 an arrival time difference to find out a defective position. Consequently, the defective position can be accurately found out without destructing the sample.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for cutting off the power supply before the sample is destroyed when conducting a voltage application test on a sample such as a cross-linked polyethylene insulated cable.

[Prior art] When performing a voltage application test on a sample such as a plastic insulated cable, a test transformer is used to apply a high voltage to the sample, and when a partial discharge occurs in the sample and breaks down, this is detected and the power is turned on. was blocking it. To remove this sample and locate the source of the partial discharge, cut the external semiconductive shielding layer of the sample cable into two parts in the length direction, and apply a voltage to both cable halves. The sample cable section on which the partial discharge source is located is further cut into two parts, and the source is determined on which side the partial discharge source is located. 3 [Problem to be solved by the invention] As mentioned above, the partial discharge source position cannot be located by repeating the process of cutting into two parts, applying voltage, and determining the source position. In order to locate the partial discharge source, repeating the steps of cutting the sample cable in two, applying voltage, and determining the source location is very labor-intensive and makes it difficult to efficiently perform a large number of tests. There was a problem.

In addition, as mentioned above, if Ml is generated in the sample and then the generation is detected and the power is cut off, the following flow immediately after the breakage occurs may damage the sample, cause burnout, and cause sample failure. It is not possible to verify defects in the sample, and electrostatic energy may be accumulated in the sample due to high voltage application, causing destruction, and it is not easy to quickly shut off the power before the sample is destroyed. there were.

In order to efficiently locate the above-mentioned partial discharge source before the sample is destroyed, it is desirable to detect the occurrence of a partial discharge, cut off the power, and locate the partial discharge source at the same time. The technology to do so has yet to be realized.

Therefore, the present invention has developed a power-applying test device that can promptly remove the electrostatic energy accumulated in the sample and quickly cut off the power supply to prevent the sample from being destroyed, as well as locate the source of partial discharge. The purpose is to provide

"Means for Solving the Problems" In order to achieve the above-mentioned object, the power charging test device of the present invention has the following features:
A power cutoff circuit section is connected to the primary side of the test transformer, a sample connection section such as a cross-linked polyethylene insulated power cable is connected to the secondary side, and a detection section for partial discharge occurring in this sample is provided. At least three accumulated electrostatic energy discharge removal circuit units are connected in parallel to the sample connection unit to close the circuit in response to a partial discharge detection signal, and at least three circuit units are configured to locate a partial discharge source of the sample. The above-mentioned positioning detector is provided, and it detects the occurrence of partial discharge in the sample, discharges and removes the electrostatic energy accumulated in the sample, and also discharges and removes the electrostatic energy of the transformer primary IP! The power supply is cut off, and at the same time, the position of the partial discharge source in the sample is located.

"Operation" Attach three or more of the partial discharge detectors described above to a sample such as a cross-linked polyethylene insulated cable that is not connected to the sample connection part, and apply a high voltage on the secondary side of the transformer to this sample cable. When a voltage application test is started, electrostatic energy is accumulated in the sample, and a partial discharge occurs to generate a discharge pulse.

When the partial discharge detection section detects this partial discharge pulse, the accumulation W? of the sample connected in parallel to the sample connection section is detected. The electric energy discharge removal circuit section closes and discharges and removes the accumulated electrostatic energy of the sample, thereby preventing the sample from being destroyed.
The power cutoff circuit on the next side cuts off the power supply circuit on the primary side before the sample is destroyed.

In addition, at least three or more positioning detectors attached to the sample will detect the partial discharge that occurs in the sample cable during voltage application at three or more points, and each detection signal will be recorded and analyzed. By doing so, it becomes possible to locate the position of the partial discharge source in the sample immediately after the power supply is shut off.

[Examples] Examples of the present invention will be described below with reference to the drawings. FIG. 1 shows a circuit of one embodiment of the present invention, where 1 is an AC commercial power supply, 2 is a test transformer, 3 is its primary winding, and 4 is a 2nd
This is the next winding.

The circuit 5 inside the dotted line is a power cutoff circuit connected in series to the primary side of the transformer, and this power cutoff circuit 5 uses power semiconductor elements such as GTO thyristors 5a and 5b in antiparallel arrangement. .

Reference numeral 6 denotes a sample connection portion for connecting sample A such as a crosslinked polyethylene insulated cable to the secondary side of the transformer, and 6a and 6b are connection terminals thereof.

7 is a coupling capacitor connected in parallel to the secondary winding 4; 8
9 is a partial discharge detector connected in series to this capacitor 7 and detects a partial discharge occurring in the sample A connected to the sample connection part 6; 9 is a trigger signal in response to the output of the partial discharge detector 8; This is a control signal generating section that generates a signal.

Reference numeral 10 denotes a stored electrostatic energy discharge removal circuit section that is connected in parallel to the sample connection section 6 and discharges and removes the accumulated electrostatic energy of the sample A. A diverter circuit parallel to the sample connection section 6 is constructed using a type diverter or the like.

A control signal output circuit 91 of the control signal generation section 9 is connected to this stored Mt electrostatic energy discharge removal circuit section 10,
The control signal triggers the circuit to close.

Further, the other fftlJ control signal output signal output circuit 95 of the control signal generation section 9 and the GTO thyristor 5a of the disconnection section 5
, 5b, and is triggered by its control signal to turn off.

Reference numeral 11 denotes detectors for locating partial discharge positions that are attached to at least three locations on the sample cable connected to the sample connection section 6, and 11a, 11b, and 11c indicate the respective detectors. This detector uses an ultrasonic sensor that detects ultrasonic waves generated from partial discharge in the sample cable or a partial discharge detector that electrically detects partial discharge pulses.

The circuit 12 within the dotted line is the position locating detector 11a, 1
a partial discharge source position locating circuit unit that receives the detection signals 1b and 11c to locate the partial discharge source;
13 is a recording device for the detection signals of the positioning detectors 11a, 11b, and Ilc, and 14 is a computer for analyzing the recorded data.

In order to conduct a voltage application test on a sample such as a crosslinked polyethylene insulated cable cable using the power cutoff device of the present invention configured as described above, connect the conductor of the sample cable and the outer surface of the insulating layer between the sample connection terminals 6a and 6b, A test voltage is applied to this sample A. As a result, electrostatic energy is accumulated in sample A, and partial discharges of various sizes occur to generate discharge pulses.

The amount of charge of this partial discharge is detected by the partial discharge detection section 8 as a voltage value corresponding thereto. When the amount of accumulated electrostatic energy of sample A increases and the amount of partial discharge charge reaches a certain level, for example, 5 picocoulombs, the output signal of the partial discharge detector 8 that has detected the corresponding voltage value is sent to the control signal generator 9. The control signal generator 9 passes through an appropriate logical operation circuit, etc., and converts the signal into a control signal free from noise, and outputs it from the control signal output circuit 91.95.

The output signal from the control signal output circuit 91 triggers the stored electrostatic energy discharge removal circuit section 10 to close the circuit.

By closing the accumulated electrostatic energy discharge removal circuit section 10, the test 'f4A! ::The accumulated electrostatic energy is discharged and removed through the circuit section 10, so that the sample A is prevented from being destroyed.

Further, the control signal output circuit 95 of the control signal generation section 9
The output signal from the GTO thyristors 5a and 5b is inputted to the power cutoff circuit 5 on the primary side of the transformer 2, and the gates of the GTO thyristors 5a and 5b are turned off to cut off the power supply circuit on the primary side of the transformer. In this way, it is possible to cut off the power supply at high speed before the sample is destroyed.

The second [21] indicates that the partial discharge pulse generated in the sample cable A is detected by the three position locating detectors 11a, 11b, and 11c attached to the sample cable A, and is generated by the partial discharge source position locating circuit section 12. source location/record,
It is a diagram for explaining that the location is calculated and oriented.
Assuming that point X of the sample cable is the partial discharge source, the ultrasonic waves (or discharge pulses) emitted from the source point The detection signal is recorded in the recording device 13, and after the power is cut off by the power cutoff circuit section 5, the recorded data of the recording device 13 is recorded in a total of $f.
In step i14, the position of the source X point is located by analysis calculation.

The position of the source X point is located as follows.

That is, the position of the partial discharge source is set to xO, and the mounting points of the three position locating detectors 11a, 11b, and 11c are set to x1, x2, and x3, respectively, and for convenience, the position of the detector 11a is For installation, assume that the point position x1 is closest to the source position χ0, and let the distance between x1 and Let the velocity of propagation inside be V, tl,
If t2 and t3 are the respective arrival times from the source position xO to the point positions x1, x2, and x3 at which each detector is attached, then Xl-XO=s (1) X2-X
OI = s+-v (t2-tl> f2)X3
-X] = s + v (t3 - tl) f3). In these equations (1) to (3), the unknowns are xOls,
v, and by solving this equation, the partial discharge source position Z
XO can be located.

According to the results of the experiment, a partial discharge was detected when the sample cable was subjected to the energization test as described above, and the accumulated electrostatic energy of the sample cable was discharged and removed by closing the accumulated electrostatic energy discharge removal circuit section 10, and the power supply was cut off. After the primary power supply circuit was cut off in the circuit section 5, the partial discharge source position xO was located for this sample cable as follows.

That is, ultrasonic sensors are used for the positioning detectors 11a, 11b, and 11C that are attached to this sample cable, and the point position of the detector 11a is set to X1=0.35 m, detector 1.
The position of 1b is X2=O, Om, and the position of detector 11c is ×3-〇. When locating the partial discharge source position XO with the setting at 35.9 for 11b
It was found that it reached the detector 11c after 76.9us, and as a result, X0=0.21m, v
= 195011/s s = 0.14m. Then, when we extracted and observed the part of the sample cable at this determined partial discharge source position was confirmed.

In addition, in the case of a long sample couple, the ultrasonic waves are attenuated, so prepare a large number of ultrasonic sensors for positioning detectors, install them along the entire length of the sample cable, and combine their outputs to determine the sensor that detects the ultrasonic waves. The computer 14 determines and analyzes the result.

Further, the position locating detectors 11a, 11b, 11
A partial discharge detector is used as c, the point position for installing the detector 11a is X1=O, Om, and the position of the detector 11b is X2.
= 6.0 m, the position of the detector 11c is X3 = 11.0
When locating the partial discharge source position xO by setting the partial discharge source position xO to
It was found that the partial discharge pulse generated at first reached the detector 11a, then reached the detector 11b after 33ns, and reached the detector 11c after 60ns, and as a result, X0=-3.5m , v=1.83xlo8m/
It was determined that s,5=3.5m. Therefore, X0 of this determined partial discharge source position of the sample cable =
-When we removed a 3.5m section and observed it, it was found that it was approximately 0.5m.
A tree with a length of 3+nm was found and confirmed to be the source of the partial discharge.

[Effects of the Invention] As described above, the present invention is provided with at least three positioning detectors for locating the partial discharge source of the sample, so that the positioning and verification of defects in the sample can be accomplished. It can be easily done.

In addition, by detecting the occurrence of partial discharge in the sample, the electrostatic energy accumulated in the sample is discharged and removed, and the primary power supply is cut off, so the power supply can be cut off at high speed before the sample is destroyed. It becomes possible to stop and inspect defects that may cause destruction at an early stage of growth without damaging or burning out the sample.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention, and FIG. 2 is an explanatory diagram of positioning. Fig. 1 2: 5: 6: 9 = 10 = Transformer 3: Primary winding 4: Secondary winding Semiconductor element power cutoff circuit section sample connection section 8: Partial discharge detection section Control signal generation section Thyristor type diverter circuit Department Patent Applicant: Furukawa Electric Co., Ltd.

Claims (1)

[Claims] a power cutoff circuit section connected to the primary side of the transformer; a sample connection section connected to the secondary side; a partial discharge detection section and a stored electrostatic energy discharge removal circuit section of the sample; 1. A power application testing device comprising at least three detectors for locating a partial discharge source position.