JP3020619B2 - Insulation inspection method for columnar insulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting the insulation of a columnar insulator having a through hole.

[0002]

2. Description of the Related Art If penetration occurs in a path 100, a path 200
Conventionally, as shown in FIG. 4, a high voltage is applied between the first electrode 300 and the second electrode 400 to visually check that the spark is flying on the path 200, as shown in FIG. Insulation inspection is performed.

[0003]

However, the above-mentioned prior art has the following disadvantages. If there is a pinhole or a crack near the one end surface 510 of the insulator 500, a spark may fly on the path 200 and an erroneous inspection may be made. An object of the present invention is to provide a method for inspecting the insulation of a columnar insulator, which can accurately inspect the insulation of the entire insulator.

[0004]

In order to solve the above-mentioned problems,
The present invention has a through hole communicating from one end surface to the other end surface, of a columnar insulator that has been confirmed to have good electrical insulation, inside the through hole recessed by a predetermined dimension from the one end surface, the outer wall side, and On one end face side away from the one end face, respectively,
A first electrode, a second electrode, and a third electrode are arranged, and a value of a discharge voltage Vb at which a discharge occurs on a surface between the first electrode and the second electrode is determined by the first electrode, the third electrode, The position of each electrode is set to be slightly higher than the value of the discharge voltage Va at which the discharge occurs in the air during the period, and the through hole of the test product for testing the electrical insulation, which has the same shape as the columnar insulator, is provided. A first electrode, a second electrode, and a third electrode are provided at the same position on the outer wall side and the one end surface side, respectively, and a high voltage is applied to the first electrode, and the first electrode and the second electrode are provided. If discharge was observed between the electrode and the electrode, the test article was assumed to have poor electrical insulation.

[0005]

[Function] If the electrical insulation of the test sample is good,
Discharge occurs between the electrode and the third electrode. If there is an insulation failure such as a pinhole or a crack anywhere in the columnar insulator of the test product, penetration occurs through the insulation failure portion, and discharge occurs inside the first electrode and the second electrode.

[0006]

According to the present invention, if there is an insulation failure such as a pinhole or a crack anywhere in the columnar insulator of the test sample, a discharge always occurs between the first electrode and the second electrode. Insulation inspection of the entire insulator can be accurately performed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS.

[0008] An insulation inspection apparatus A employing the configuration of the present invention.
Are the insulator 2 on which the insulator 1 to be tested is placed, the first electrode 3 inserted into the shaft hole 11, the second electrode 4 provided around the outer wall 12, and the upper end face 13. Third installed above
The apparatus includes an electrode 5, a high voltage generator 6 for generating a high voltage pulse, and a comparison detection circuit 7 electrically connected to each electrode.

The insulator 1 is formed of a ceramic such as alumina, silicon nitride, and aluminum nitride, and has an outer diameter of 10 mm.
A cylindrical body having a length of 50 mm and a shaft hole diameter of 2 mm.

The insulator 2 is provided to prevent discharge from the lower side. The insulator 2 is provided by fitting the convex central portion 21 into the shaft hole 11 and supporting the lower end surface 14 of the insulator 1 on the upper surface 22. The insulator 1 is erected.

The first electrode 3 has a round bar shape and, as shown in FIG.
1 and the rear end thereof is connected to the output side of the high voltage generation circuit 6.

The second electrode 4 has a cylindrical shape, is fitted to the outer wall 12 such that the upper portion 41 is located at a distance of the creepage distance c1 from the upper end surface 13, and is grounded via the detection resistor 42.

The third electrode 5 has a disk shape, is disposed in parallel with the upper end face 13 at a distance L from the upper part 41, and is grounded via a detection resistor 51.

The high-voltage generating device 6 is a device for generating a continuous pulse 61 of a high voltage (the voltage value is adjustable). The high-voltage output terminal is connected to the first electrode 3, and the high-voltage generating signal is output to a comparison detection circuit. 7 has been entered.

The comparison detection circuit 7 has input terminals to which the continuous pulse 61 and the discharge signals 43 and 52 are input. Further, a display element (not shown) is provided.

Next, using the insulation inspection apparatus A, the insulator 1
A method for performing an insulation test on a substrate will be described.

(1) A columnar insulator having good electrical insulation is prepared, and the value of the discharge voltage Vb at which the discharge occurs on the surface between the first electrode 3 and the second electrode 4 is equal to that of the first electrode 3. The electrodes 3, 4, and 5 are positioned so as to be slightly higher than the value of the discharge voltage Va at which discharge occurs in the air between the three electrodes 5. As a result of various experiments, in the case of a ceramic cylindrical body in which holes having a circular cross-section and having the same diameter are formed on the axis of a cylindrical body having the same diameter, the electrodes 3, 4, 5, and 6 are simultaneously satisfied so that It was found that the discharge voltage Va was smaller than the discharge voltage Vb if the position was set. 0.4L ≦ l ≦ 0.6L a1 + b1 + c1> L where a1, b1, and c1 are creepage distances, l is the distance between the distal end surface 31 and the upper end surface 13 of the first electrode 3, and L is the distal end surface of the first electrode 3. The distance between the third electrode 31 and the third electrode 5.

(2) Next, a columnar insulator 1 to be subjected to an insulation test is prepared, and the values of the creepage distances a1, b1, c1, and the distances l and L are made the same as above, and the first electrode 3 and the second electrode 4th, 3rd
The electrode 5 is provided.

(3) When a high voltage continuous pulse 61 generated by the high voltage generator 6 is applied to the first electrode 3, a discharge S1 occurs between the first electrode 3 and the third electrode 5, and a discharge signal 5
2 is input to the comparison detection circuit 7.

(4) If there is an insulation failure such as a pinhole or a crack at the center of the columnar insulator 1, the first electrode 3 and the second
Discharge S2 (penetration) occurs inside the electrode 4 and the discharge signal 43 is input to the comparison detection circuit 7. Further, when there is an insulation failure near the upper end surface 13, there is also a case where the discharge signal 43 penetrates at a position intermediate between the first electrode 3 and the second electrode 4 and further reaches the creeping discharge S 3. It is input to the comparison detection circuit 7. When the discharge S2 or the discharge S3 occurs, the discharge S1 does not occur, and the discharge signal 52 does not occur.
When the insulating property of the columnar insulator 1 is good, only the discharge S1 occurs and the discharge signal 43 does not occur.

(5) The comparison detection circuit 7 generates the penetration signal 71 based on the discharge signal 43, and keeps turning on the display element when the penetration signal 71 is detected even once during a predetermined time.

Next, the effect of this embodiment will be described.

(A) Regardless of the insulation defect such as a pinhole or a crack in any place of the columnar insulator 1, the display element of the comparison detection circuit 7 turns on the defective columnar insulator 1 by turning on the display element. Can be easily grasped.

(I) Since it is not necessary for the inspector to visually observe the discharges S1 and S2 during the inspection, there is no erroneous determination due to oversight of the discharge, and the reliability of the inspection result is extremely high.

(C) If the columnar insulators 1 have the same shape,
The first electrode 3, the second electrode 4, and the third electrode 5 may be arranged at the same position, and the inspection can be performed continuously.

The present invention includes the following embodiments in addition to the above embodiments.

A. Each cross-sectional shape of the one end face, the other end face, and the through hole of the columnar insulator may be an ellipse or a polygon other than a circle. Further, the outer diameter of the columnar insulator and the diameter of the through hole may be different in size depending on the location. Further, the through holes may be eccentric.

There may be a gap between the first electrode and the through-hole of the columnar insulator, and the second electrode may not be in contact with the outer wall of the columnar insulator.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an insulation inspection apparatus according to one embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the device.

FIG. 3 is a waveform diagram input to a comparison detection circuit of the device.

FIG. 4 is an explanatory diagram for explaining a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Columnar insulator 3 1st electrode 4 2nd electrode 5 3rd electrode 11 Shaft hole (through-hole) 12 Outer side wall 13 Upper end surface (one end surface) 14 Lower end surface (other end surface) Va, Vb Discharge voltage S1, S2, S3 Discharge

Claims (1)

(57) [Claims] 1. A columnar insulator having a through hole communicating from one end face to the other end face and having been confirmed to have good electrical insulation.
A first electrode, a second electrode, and a third electrode are disposed on the inside of the through hole recessed by a predetermined dimension from the one end face, on the outer wall side, and on one end face side apart from the one end face, respectively. The value of the discharge voltage Vb at which the discharge occurs on the surface between the first electrode and the second electrode is slightly higher than the value of the discharge voltage Va at which the discharge occurs in the air between the first electrode and the third electrode. The first electrode is positioned at the same position on the inside of the through-hole, on the outside wall side, and on one end face side of the test product for testing electrical insulation, which has the same shape as the columnar insulator, and positions the electrodes. , A second electrode, and a third electrode, and applying a high voltage to the first electrode,
A method for inspecting the insulation of a columnar insulator, wherein if the discharge is observed between the electrodes, the test article has poor electrical insulation.