JPH1123636A - Method and apparatus for measuring insulation resistance of array type capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform measurement of three mode insulation resistance efficiently. SOLUTION: When the insulation resistance of an array type capacitor 1 comprising a plurality of capacitor elements C1-C4 arranged in parallel is measured, a DC voltage of same polarity to respective capacitor elements C1-C4 and the leakage currents (1)/(2) thereof are detected. Subsequently, switches 47a-47d are switched to apply the adjacent capacitor elements C1-C4 with DC voltages of reverse polarities and the leakage currents (1)/(1)/(3) thereof are detected. Based on these leakage currents, insulation resistance of each capacitor element, detective insulation between the inner electrodes of adjacent capacitor elements and defective insulation between the outer electrodes of adjacent capacitor elements are detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for measuring the insulation resistance of an array type capacitor.

[0002]

2. Description of the Related Art Generally, an insulation resistance value is measured to determine the quality of a capacitor. When measuring the insulation resistance value, when the capacitor is not charged, the insulation resistance cannot be measured correctly due to the capacity of the capacitor. Therefore, a method of measuring the insulation resistance of a capacitor by first applying a DC voltage to the capacitor and precharging the capacitor, and then measuring the leakage current (charging current) is generally used. Naturally, good products have low leakage current.

An array-type capacitor 1 in which a plurality of capacitor elements C1 to C4 are arranged in parallel as shown in FIGS. 1 and 2 is known. The array-type capacitor 1 is provided with opposing internal electrodes 5a to 5h between a plurality of dielectric layers 2 to 4 so that all the layers 2 to 4 are laminated and integrated, and are electrically connected to the internal electrodes 5a to 5h. Provided with external electrodes 6a to 6h. In FIG. 1, for simplicity of description,
Although three dielectric layers are used, four or more dielectric layers may be used. Also, the number of capacitor elements is not limited to four, but may be two or three.
Of course, the number may be five or more.

[0004] There are the following three modes in the failure mode of the insulation resistance of such an array type capacitor. Mode 1: Insulation failure of capacitor elements C1-C4 itself Mode 2: Internal electrodes 5a-5 of adjacent capacitor elements
Insulation failure between h Mode 3: External electrodes 6a-6 of adjacent capacitor elements
Insulation failure between h

Conventionally, in order to detect the above three modes of insulation failure, the wiring of the insulation resistance measuring circuit is rearranged as shown in FIG. That is, FIG.
The measurement circuit of FIG.
11 is contacted and the current in the direction is measured to detect the insulation resistance of the capacitor elements C1 to C4 themselves. In the figure, 12 is a DC power supply, 13 is an AC power supply for contact detection, 14 is a changeover switch, 15 is a current limiting resistor,
Reference numeral 16 denotes an ammeter. Although FIG. 3 shows only the measurement circuit for one element, the measurement circuits may be provided in parallel according to the number of elements, and the insulation resistances of all the elements C1 to C4 may be measured simultaneously. FIG. 3B shows a measurement circuit of mode 2, in which the internal electrodes 5a to 5h are measured by measuring currents flowing in diagonal directions in adjacent capacitor elements C1 to C4.
Insulation failure between them is detected. FIG. 3C shows the mode 3
Measuring the current flowing between the adjacent capacitor elements C1 to C4 to obtain the external electrode 6a
Insulation failures of up to 6 h are detected.

[0006]

However, when trying to measure the insulation resistance with the above-described measuring circuit, it is necessary to rearrange the wiring of the measuring circuit for each of the failure modes 1 to 3, and the measurement efficiency is very poor. Further, it is necessary to detect the contact between the measurement terminals 10 and 11 before measuring the insulation resistance. For this purpose, the switch 14 is switched to the AC power supply 13 to detect the current flowing through the circuit. Since the detection needs to be performed before the measurement in each mode, the measurement work is further complicated. Moreover, in Modes 2 and 3, the measurement of insulation failure between adjacent inner and outer electrodes has a small capacitance (for example, several pF or less) of the stray capacitance, so that there is a problem that contact detection cannot be effectively performed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for measuring the insulation resistance of an array-type capacitor, which can efficiently measure the insulation resistance in three modes.

[0008]

In order to achieve the above-mentioned object, according to the first aspect of the present invention, a DC voltage is applied to an array-type capacitor in which a plurality of capacitor elements are arranged in parallel, and an insulation resistance is determined from a leakage current. In a method of measuring insulation resistance, a first step of applying a DC voltage of the same polarity to each capacitor element and detecting a leakage current thereof, and a DC voltage of an opposite polarity to each capacitor element for each adjacent capacitor element From the leakage current obtained from the first and second steps, the insulation resistance of each capacitor element, insulation failure between internal electrodes of adjacent capacitor elements, And a step of detecting insulation failure between external electrodes of adjacent capacitor elements.

First, a DC voltage of the same polarity is applied to each capacitor element, and its leakage current is detected. This leakage current includes a current in mode 1 and a current in mode 2. Next, a DC voltage of opposite polarity is applied to each capacitor element for each adjacent capacitor element, and the leakage current is detected. This leakage current includes a current in mode 1 and a current in mode 3. If any one of the two types of currents obtained as described above has a very large current value, it means that there is insulation failure in any of modes 1 to 3, and this array-type capacitor is not suitable. It turns out that it is good. On the other hand, when the two types of currents fall in a predetermined time curve, it means that there is no insulation failure in mode 1 to mode 3 and that the array type capacitor is a non-defective product. The insulation resistance of the capacitor element is determined from the leakage current obtained from the second step. Note that, of course, any of the first step and the second step may be performed first.

In the first step and the second step, the measuring terminal is brought into contact with the external electrode of the array type capacitor. If the contact is insufficient, the measured current value may be inaccurate. It will be. Therefore, before the first step or the second step, it is desirable to apply an AC voltage to each capacitor element and detect contact from the flowing current. When the contact is insufficient, the flowing current is small, so that the contact failure can be easily determined. Further, in the measurement of the mode 2 or the mode 3 alone, it was difficult to detect the contact because there was only a small capacitance about the stray capacitance. However, in the present invention, the mode 2 and the mode 1 were simultaneously performed, or the mode 3 and the mode 1 were compared. Are detected at the same time, the capacitance value is large, and contact detection can be reliably performed. When the first step and the second step are performed by separate measurement circuits, it is necessary to perform contact detection before each of the first step and the second step. On the other hand, when the first step and the second step are performed by a common circuit having a changeover switch, the first step and the second step can be performed continuously, so that the contact detection is performed by the first circuit. It only needs to be performed before the process.

In the above measuring method, mode 1 and mode 2
Are simultaneously detected, and mode 1 and mode 3 are simultaneously detected. Therefore, it is difficult to accurately measure only the insulation resistance of the capacitor element alone. That is, the measured current value is a combined value of the two modes. Therefore, in order to measure the insulation resistance of a single capacitor element, it is desirable to apply a DC voltage to each capacitor element at a different timing for each adjacent capacitor element. As this timing, for example, a DC voltage may be applied to the capacitor elements arranged in parallel while scanning, or a DC voltage may be applied to every other capacitor element. In this case, a value that is not affected by the adjacent capacitor element, that is, the insulation resistance of the capacitor element alone can be accurately measured.

[0012]

4 and 5 show a first embodiment of the insulation resistance measuring apparatus according to the present invention. This example is
This is an example in which measurement in modes 1 and 2 and measurement in modes 1 and 3 are performed by separate circuits. The array-type capacitor 1 to be measured used was a capacitor including four capacitor elements C1 to C4 as in FIGS. FIG. 4 shows a first measuring circuit 20 for performing the measurement in the mode 1 and the mode 2, in which eight measuring terminals 21a to 21h respectively contacting the external electrodes 6a to 6h of the array type capacitor 1, a DC power supply 22, a contact detection. Power supply 23, power switch 2
4, four current limiting resistors 25a to 25d, four ammeters 26a to 26d, and four switches 27a to 27d. The current limiting resistors 25a to 25d, the ammeter 26
a to 26d and switches 27a to 27d are connected in parallel with each other. FIG. 5 shows a second measurement circuit 30 for performing measurement in mode 1 and mode 3, in which eight measurement terminals 31a to 31h contacting the external electrodes 6a to 6h of the array type capacitor 1, a DC power supply 32, AC power supply 33 for contact detection, power supply switch 34, four current limiting resistors 35a to 35d, four ammeters 36a to 36
d, four switches 37a to 37d.

First, a method of measuring modes 1 and 2 using the first measuring circuit 20 will be described. After the measurement terminals 21a to 21h are brought into contact with the external electrodes 6a to 6h, first, the switch 24 is switched to the AC power supply 23 side, and all the switches 27a to 27d are turned on to apply an AC signal to the capacitor elements C1 to C4. And ammeter 26
Contact detection is performed from the detection values of a to 26d. If it is determined that the contact is good, all the switches 27a to 27a
27d is turned off, and the switch 24 is switched to the DC power supply 22 side. Then, switches 27a to 27d
Is turned on to apply a DC voltage to the capacitor elements C1 to C4, and the leakage current is measured by the ammeters 26a to 26d.
At this time, since current flows in the same direction in each of the capacitor elements C1 to C4, the ammeters 26a to 26d determine the current flowing through the capacitor elements and the adjacent capacitor elements C1 to C4.
4 and the current flowing between the internal electrodes 4 is measured. If there is insulation failure in either mode 1 or 2,
Since this current value is very large, insulation failure can be easily detected. On the other hand, when the current falls along a predetermined time curve, the insulation resistance of the capacitor element can be known from the leakage current value after the predetermined time. It should be noted that this leakage current value has the value of the adjacent capacitor elements C1 to C
Although the current flowing between the internal electrodes 4 is also included, this current is very small unless insulation between the internal electrodes is poor, and can be almost ignored.

In the above case, the sum of the current values is measured by the ammeters 26a to 26d, and the insulation resistance of the capacitor elements C1 to C4 is estimated from the measured values.
It is also possible to accurately measure the insulation resistance of each of the capacitor elements C1 to C4 by measuring only the current value using the following method. That is, the contact detection ends, and the switch 2
4 to the DC power supply 22 side, and then switches 27a to
A method is used in which switches 27a to 27d are switched so that DC voltages are applied at different timings to adjacent capacitor elements, instead of turning ON simultaneously. Specifically, for example, the switch 27a is connected to the switch 2
7d, the capacitor elements C1 to C
4, a method of applying a DC voltage in order, or a method of applying a DC voltage to every other capacitor element (for example, when the switches 27a and 27c are turned on, the switch 2
7b and 27d are turned off).

Next, a method of measuring modes 1 and 3 using the second measuring circuit 30 will be described. After the measurement terminals 31a to 31h are brought into contact with the external electrodes 6a to 6h, the switch 34 is first switched to the AC power supply 33 side, and all the switches 37a to 37d are turned on to apply an AC signal to the capacitor elements C1 to C4. And ammeter 36
Contact detection is performed from the detection values of a to 36d. If it is determined that the contact is good, all the switches 37a to 37a
37d is turned off, and the switch 34 is switched to the DC power supply 32 side. Then, switches 37a to 37d
Is turned on to apply a DC voltage to the capacitor elements C1 to C4, and the leakage current is measured by the ammeters 36a to 36d.
At this time, a reverse current flows through each of the capacitor elements C1 to C4 for each adjacent element.
c measures the sum of the current flowing in the capacitor element and the current flowing between the external electrodes of the adjacent capacitor elements C1 to C4, and the ammeters 36b and 36d measure the current 'flowing in the capacitor element and the adjacent capacitor element. The sum with the current flowing between the external electrodes C1 to C4 will be measured. As in the case of the first measurement circuit 20, if there is an insulation failure in either mode 1 or mode 3, the current value becomes very large, so that the insulation failure can be easily detected.
On the other hand, if this current decreases in a predetermined time curve, it means that there is no insulation failure in modes 1 and 3, and the insulation resistance of the capacitor elements C1 to C4 is determined from the leakage current value after the predetermined time. You can know. Note that the insulation resistance of the capacitor elements C1 to C4
Since the measurement has already been performed in FIG. 4 (see FIG. 4), there is no need to measure again, and it is sufficient to confirm that there is no insulation failure in mode 3.

In the measurement circuit 30, when measuring the insulation resistance of each of the capacitor elements C1 to C4, as described in the description of the measurement circuit 20, the switch 37 is used.
a to 37d are not turned on at the same time, and a DC voltage is applied at a different timing for each adjacent capacitor element.
The switching may be performed by the switches 37a to 37d.

FIG. 6 shows a second embodiment of the insulation resistance measuring apparatus according to the present invention. This embodiment is an example in which the measurements in modes 1 to 3 are performed by a single circuit. The array-type capacitor 1 to be measured used was a capacitor including four capacitor elements C1 to C4 as in FIGS. The measuring circuit 40 includes the external electrodes 6 a to 6
h measuring terminals 41a to 41h,
DC power supply 42, AC power supply 43 for contact detection, power supply switch 44, six current limiting resistors 45a to 45f, six ammeters 46a to 46f, and four switches 47a to 47
d.

Next, mode 1 using the measuring circuit 40 is described.
The measurement methods 3 to 3 will be described with reference to the flowchart of FIG. First, the measurement terminals 41 a to 41 h are connected to the external electrodes 6.
a to 6h (step S1), and switches the switch 44 to the AC power supply 43 side (step S1).
2) All the switches 47a to 47d are set to the solid line positions (step S3), and the AC signals are
4 is applied. Then, contact detection is performed from the detection values of the ammeters 46a to 46d (step S4). When it is determined that the contact is good, the switch 44 is switched to the DC power supply 42 while the switches 47a to 47d are kept at the solid line positions (step S5). Thus, a DC voltage is applied to the capacitor elements C1 to C4, and the leakage current is measured by the ammeters 46a to 46d. At this time, since currents flow in the same direction in each of the capacitor elements C1 to C4, the ammeters 46a to 46d calculate the sum of the current flowing in the capacitor elements and the current flowing between the internal electrodes of the adjacent capacitor elements C1 to C4. Will be measured. That is, the measurement in modes 1 and 2 can be performed (step S
6). After the measurement of the modes 1 and 2 is completed, the switch 44
Switches 47a to 47d while
To the broken line position (step S7). Thereby, the direct current flows in the direction of the capacitor elements C1 and C3,
The current flows through the capacitor elements C2 and C4 in the 'direction, and a current flows in the opposite direction for each adjacent element. At the same time, current flows in the direction between the external electrodes of the adjacent capacitor elements C1 to C4. Therefore, the ammeters 46a, 46
6c, 46e and 46f denote currents flowing through the capacitor elements C1 to C4, 'and adjacent capacitor elements C1 to C4.
Is measured with the current flowing between the external electrodes. That is, the measurement in modes 1 and 3 can be performed (step S8). From the above measurement results, the insulation resistance of the capacitor elements C1 to C4, the insulation failure between the internal electrodes, and the insulation failure between the external electrodes can be detected. The specific method is the same as that described in the first embodiment, and a duplicate description will be omitted. In the above description, the case where the switches 47a to 47d are simultaneously switched has been described. However, as described in the first embodiment,
By switching each of the switches 47a to 47d while scanning, or by switching every other switch, a DC voltage may be applied to each adjacent capacitor element at a different timing. As a result, only the current value of ′ can be measured, and the insulation resistance of the capacitor element alone can be accurately known.

FIG. 8 shows a third embodiment of the insulation resistance measuring apparatus according to the present invention. This embodiment is a modification of the second embodiment, in which the number of ammeters is reduced to four as compared with the second embodiment. The same parts as those in FIG. 6 are denoted by the same reference numerals, and redundant description will be omitted. In the case of this measurement circuit 50, the contact on the solid line side of the switch 47a and the contact on the broken line side of the switch 47b are connected by the wiring 51, and the switch 47
The contact on the solid line side of c and the contact on the broken line side of the switch 47d are connected by the wiring 52. Therefore, the capacitor element C
2, the current flowing in the forward and reverse directions flowing through C4,
6b and 46d can be measured together, and the ammeter 46 in FIG.
e, 46f could be omitted.

It should be noted that the ammeter used in the present invention is not limited to an analog type measuring instrument, but is amplified by an OP amplifier or the like.
The current value may be measured by a digital signal after performing the / D conversion. As a method of measuring the insulation resistance of the capacitor element, a method of measuring the insulation resistance of the capacitor element from a leakage current value after a predetermined precharge (for example, after 60 seconds) according to JIS standards is generally used. Not limited to the method, a method of estimating the current value at the end of charging from the current value at the beginning of charging or any other method may be used. Also, this time, the method of switching between AC power supply (for contact detection) and DC power supply (for insulation resistance measurement) was used. However, by superimposing AC voltage on DC voltage, there is no switching between contact detection and insulation resistance measurement. It is also possible to do it.

[0021]

As is clear from the above description, according to the present invention, a DC voltage having the same polarity is applied to each capacitor element of the array type capacitor to detect the leakage current, and each adjacent capacitor element A DC voltage of opposite polarity is applied to the capacitor to detect its leakage current. From these two types of current, the insulation resistance of each capacitor element, insulation failure between the internal electrodes of adjacent capacitor elements, and the external Since the insulation failure between the electrodes is detected, it is not necessary to rearrange the wiring of the measurement circuit for each failure mode, and the measurement efficiency is improved. Further, in the present invention, since the mode 2 and the mode 1 or the mode 3 and the mode 1 are detected at the same time, the respective capacitance values are large, and it is necessary to detect the contact between the measurement terminal and the external electrode of the array type capacitor. It can be performed reliably.

[Brief description of the drawings]

FIG. 1 is a perspective view of an example of an array-type capacitor.

FIG. 2 is an exploded perspective view of the array-type capacitor shown in FIG.

FIG. 3 is a circuit diagram showing a conventional method of measuring the insulation resistance of an array-type capacitor.

FIG. 4 is a circuit diagram of a first measuring circuit of the insulation resistance measuring device according to the present invention.

FIG. 5 is a circuit diagram of a second measuring circuit of the insulation resistance measuring device according to the present invention.

FIG. 6 is a circuit diagram of a second embodiment of the insulation resistance measuring device according to the present invention.

FIG. 7 is a flowchart illustrating the operation of the insulation resistance measuring device of FIG. 6;

FIG. 8 is a circuit diagram of a third embodiment of the insulation resistance measuring device according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 Array type capacitor C1 to C4 Capacitor element 20, 30, 40, 40 Measurement circuit 21a to 21h Measurement terminal 22 DC power supply 23 AC power supply 24 Power supply changeover switch 25a to 25d Current limiting resistor 26a to 26d Ammeter 27a to 27d Switch

Claims (7)

[Claims] In an insulation resistance measuring method for applying a DC voltage to an array type capacitor having a plurality of capacitor elements arranged in parallel and measuring an insulation resistance from a leakage current, a DC voltage having the same polarity is applied to each capacitor element. A first step of detecting the leakage current, and a second step of applying a reverse-polarity DC voltage to each capacitor element for each adjacent capacitor element and detecting the leakage current.
And the leakage current obtained from the first and second steps,
Detecting the insulation resistance of each capacitor element, insulation failure between internal electrodes of adjacent capacitor elements, and insulation failure between external electrodes of adjacent capacitor elements. Measuring method. 2. The method according to claim 1, wherein before the first step or the second step,
2. The method according to claim 1, further comprising the step of applying an AC voltage to each capacitor element and detecting contact from a flowing current.
3. The method for measuring the insulation resistance of an array-type capacitor according to item 1. 3. The method according to claim 1, wherein a DC voltage is applied to each capacitor element at a different timing for each adjacent capacitor element, and an insulation resistance of each capacitor element is obtained from a leakage current. Measurement method for insulation resistance of array type capacitors. 4. An insulation resistance measuring apparatus for applying a DC voltage to an array type capacitor having a plurality of capacitor elements arranged in parallel and measuring an insulation resistance from a leakage current thereof, comprising: a first DC power supply; A first measuring circuit for applying a DC voltage to the capacitor elements in the same direction and detecting a leakage current flowing through each capacitor element; and a second DC power supply, wherein adjacent capacitors are provided for all capacitor elements. An insulation resistance measuring device for an array-type capacitor, comprising: a second measuring circuit for applying a DC voltage of opposite polarity to each element and detecting a leakage current. 5. An insulation resistance measuring device for applying a DC voltage to an array-type capacitor having a plurality of capacitor elements arranged in parallel and measuring an insulation resistance from a leakage current thereof, wherein the DC power supply is connected to the DC power supply. A first circuit unit for applying a DC voltage of the DC power supply to the first capacitor element in one direction and detecting a leakage current thereof; a first capacitor element connected to the DC power supply; And a second circuit unit for detecting the leakage current of the second capacitor element adjacent to the second capacitor element by switching means to apply the DC voltage of the DC power supply with the same polarity and opposite polarity to the adjacent capacitor element. An insulation resistance measuring device for an array-type capacitor, characterized in that: 6. The array type according to claim 4, wherein an AC power supply is provided in parallel with said DC power supply, and switch means for selectively switching between the DC power supply and the AC power supply is provided. Capacitor insulation resistance measuring device. 7. The switch according to claim 4, wherein each capacitor element is provided with switch means for switching a circuit so as to apply a DC voltage at a different timing for each adjacent capacitor element. For measuring the insulation resistance of array type capacitors.