JP2009216528A - Insulation inspection method and insulation inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulation inspection method and an insulation inspection device, capable of inspecting an insulation state of an inspection object in a short time. <P>SOLUTION: This insulation inspection method/device is provided with an electric power source part 3 for impressing a direct current voltage V1 between probes 2a, 2b connected to wiring patterns 11a, 11b, an ammeter 4 for measuring leak currents I<SB>L</SB>flowing in the probes 2a, 2b in an impressed state of the direct current voltage V1, and a processing part 5 for inspecting the insulation state of the wiring patterns 11a, 11b, based on the leak currents I<SB>L</SB>and a threshold value I<SB>Lth</SB>, and the processing part 5 executes a stationary value storage processing for storing a stationary value I<SB>Lo</SB>of the leak currents I<SB>L</SB>measured by the ammeter 4, when the direct current voltage V1 is impressed between the probes 2a, 2b, under an unconnected state of the wiring patterns 11a, 11b, and inspection processing for subtracting the stationary value I<SB>Lo</SB>from the current value of the leak currents I<SB>L</SB>measured by the ammeter 4, when the direct current voltage V1 is impressed, under a connected state of the wiring patterns 11a, 11b, and for inspecting the insulation state, based on a current value obtained by the subtraction and the threshold value I<SB>Lth</SB>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an insulation inspection method and an insulation inspection apparatus for inspecting an insulation state of an inspection object based on a current value of a leakage current that flows when a DC voltage is applied to the inspection object.

As this type of insulation inspection apparatus, the applicant of the present application has proposed a circuit board inspection apparatus for performing an insulation inspection in Patent Document 1 below. This insulation inspection apparatus performs insulation inspection of a pair of conductor patterns as inspection targets, and includes a pair of inspection probes for applying an inspection voltage between a pair of conductor patterns and a plurality of input ranges. A range circuit that converts the current between inspection probes to a voltage at a controlled conversion rate for each input range, a control circuit that switches and controls the input range from the input range for large current to the input range for small current, And an arithmetic circuit for calculating an insulation resistance value between the conductor patterns. In this insulation inspection device, the control circuit switches and controls the input range when it reaches a reference value that is lower than the lower limit value in the rated current range of each input range. For this reason, compared with a conventional insulation inspection device that switches and controls the input range when the current reaches the lower limit value within the rated current range of each input range, the capacity between the pair of conductor patterns is larger. And is charged for a longer time. Therefore, the capacity is quickly charged as compared with the current characteristic in the conventional insulation inspection apparatus, and the state where the insulation resistance value can be calculated in a shorter time is reached. As a result, according to this insulation inspection apparatus, it is possible to perform the insulation inspection on the pair of conductor patterns in a shorter time and with higher accuracy.
JP 2001-91562 A (page 4-5, FIG. 1)

  By the way, the conventional insulation inspection apparatus has a range circuit having a plurality of input ranges. However, there is an insulation inspection device that does not include a range circuit for switching the input range, that is, an insulation inspection device in which the input range is fixed to one. There are many requests to shorten inspections. In addition, in the above-described conventional insulation inspection device (inspection device having a plurality of input ranges), after reaching the low current input range suitable for measuring the insulation resistance value by switching the input range, the current value Therefore, it is desirable to further reduce the time in this portion.

  This invention is made | formed in view of this subject, and it aims at providing the insulation test | inspection method and insulation test | inspection apparatus which can test | inspect the insulation state of a test object in a short time.

  In order to achieve the above object, the insulation inspection method according to claim 1 applies a DC voltage between a pair of probes connected to an object to be inspected, and a leakage current that flows through the pair of probes when the DC voltage is applied. An insulation inspection method for inspecting an insulation state of the inspection object based on a current value and a predetermined threshold value, wherein the DC voltage is applied between the pair of probes in an unconnected state of the inspection object. The leakage current in the applied state of the DC voltage is measured when a steady-state value of the leakage current is measured, and the inspection object is connected between the pair of probes to perform the inspection of the insulation state. The steady state value is subtracted from the measured current value while measuring the current value, and the insulation state is inspected based on the current value obtained by the subtraction and the threshold value.

  According to a second aspect of the present invention, in the insulation inspection method according to the first aspect, the steady-state value is periodically measured when the insulation state inspection is not performed.

  According to a third aspect of the present invention, in the insulation inspection method according to the second aspect, the steady-state value is measured at predetermined time intervals.

  According to a fourth aspect of the present invention, in the insulation inspection method according to the first aspect, the steady-state value is measured each time the insulation state inspection for a predetermined number of the inspection objects is completed.

  The insulation inspection apparatus according to claim 5 is a pair of probes connected to an inspection object, a power supply unit that applies a DC voltage between the pair of probes, and the pair of probes in the DC voltage application state. And a processing unit for inspecting the insulation state of the inspection object based on the measured current value of the leakage current and a predetermined threshold value. In the insulation inspection apparatus, the processing unit is configured to measure the leakage measured by the current measurement unit when the DC voltage is applied between the pair of probes from the power supply unit in a state where the inspection object is not connected. A steady-state storage process for storing a steady-state value for the current, and when the DC voltage is applied between the pair of probes from the power supply unit in the connection state of the inspection object, the current measurement unit And subtracting the steady value from the measured current value while measuring the current value of the leakage current, and inspecting the insulation state based on the current value obtained by the subtraction and the threshold value The inspection process is executed.

  According to a sixth aspect of the present invention, in the insulation testing apparatus according to the fifth aspect, the processing unit executes the steady value storage process within a predetermined period immediately after the power is turned on.

  The insulation inspection apparatus according to claim 7 is the insulation inspection apparatus according to claim 5, wherein the processing unit periodically executes the steady value storage process when the inspection process is not executed.

  The insulation inspection apparatus according to claim 8 is the insulation inspection apparatus according to claim 7, wherein the processing unit executes the steady value storage process at predetermined time intervals.

  In addition, the insulation inspection apparatus according to claim 9 is the insulation inspection apparatus according to claim 5, wherein the processing unit executes the steady value storage process every time the inspection process for a predetermined number of the inspection objects is completed. To do.

  The insulation inspection method according to claim 1 and the insulation inspection apparatus according to claim 5 measure a steady value of a leakage current flowing through a probe when a DC voltage is applied between a pair of probes in an unconnected state of an inspection object. Then, when connecting the test object between the pair of probes and performing the insulation test, the steady value is subtracted from the current value while measuring the current value of the leakage current in the DC voltage application state, The current value obtained by subtraction is compared with a threshold value, and the insulation state (insulation quality) of the inspection object (between each probe) is inspected. Therefore, according to the insulation inspection process and the insulation inspection apparatus, by measuring the steady value in advance, when the insulation failure does not occur in the inspection object, the leakage current becomes the threshold value by the amount obtained by subtracting the steady value. Since it arrives early, it can test | inspect further in a short time that the insulation state of a test object is favorable.

  According to the insulation inspection method described in claims 2, 3, and 4 and the insulation inspection device described in claims 7, 8, and 9, the measurement and storage of the steady value are periodically performed when the inspection of the insulation state of the inspection object is not performed. (For example, one or more times between inspections in an insulated state), measurement and storage of steady values at predetermined time intervals, and completion of inspection processing for a predetermined number of inspection objects By measuring and storing steady values each time, steady values that are likely to change depending on the surrounding environment, such as humidity, can be stored in correspondence with the constantly changing surrounding environment. The accuracy of the insulation test can be further improved.

  According to the insulation inspection apparatus of the sixth aspect, since the processing unit executes the steady value storage process within a predetermined period immediately after the power is turned on, the insulation value is actually inspected with respect to the steady value that easily changes depending on the surrounding environment such as humidity. It can be stored in the storage unit in correspondence with the surrounding environment when processing is performed. For this reason, it is possible to improve the accuracy of the insulation inspection while shortening the inspection time.

  Hereinafter, the best mode of an insulation inspection method and an insulation inspection apparatus according to the present invention will be described with reference to the accompanying drawings.

  Initially, the structure of the insulation test | inspection apparatus 1 which concerns on this invention is demonstrated with reference to drawings.

  1 includes a pair of probes 2a and 2b, a power supply unit 3, an ammeter 4 as a current measuring unit in the present invention, a processing unit 5, a storage unit 6, an output unit 7, and an operation unit 8. The insulation inspection for the inspection object can be executed. One probe 2 a of the pair of probes 2 a and 2 b is connected to an output terminal (not shown) of the power supply unit 3, and the other probe 2 b is connected to the ammeter 4. Moreover, each probe 2a, 2b is comprised so that a test subject can be contacted. In the figure, the capacitance denoted by Cs indicates the stray capacitance between the probes 2a and 2b (capacitance when the test object is not connected. As an example, approximately 100 nF), and denoted by Rp. The resistance shown represents the insulation resistance between the probes 2a and 2b (insulation resistance when the test object is not connected, as an example, about 1 GΩ). The power supply unit 3 is controlled by the processing unit 5 and outputs a predetermined DC voltage V1 (voltage based on the ground potential, 100V as an example) from its output terminal (not shown). In the figure, the resistor denoted by reference numeral 3 a indicates the output resistance of the power supply unit 3.

As shown in FIG. 1, the ammeter 4 is interposed between the probe 2b and the ground. The current meter 4, a pair of probes 2a, the current value of the leakage current I _L flowing between 2b with measured at a predetermined sampling period, every measurement, and outputs the data Di indicating the measured current value. The processing unit 5 is configured by a CPU as an example, and executes an insulation inspection process on the inspection object. The storage unit 6 is composed of a semiconductor memory, and stores a steady value I _L0 measured by the processing unit 5 when the insulation inspection process is executed. The storage unit 6 stores in advance a threshold value I _Lth for insulation inspection. The output unit 7 is constituted by a display device as an example, and displays the result of the insulation inspection process executed by the processing unit 5. The operation unit 8 has a function of inputting an operation instruction to the processing unit 5.

Next, the insulation inspection process will be described together with the operation of the insulation inspection apparatus 1. An example in which two wiring patterns formed on a circuit board are used as inspection objects and an insulation state between the two wiring patterns is inspected will be described. Further, in order to determine that the insulation between the wiring patterns 11a and 11b is good when the insulation resistance Rx is 100 MΩ or more, a threshold value I _Lth (= 1 μA (= 100 V / 100 MΩ)) is stored in advance.

In this insulation inspection process, first, before connecting each probe 2a, 2b to the wiring patterns 11a, 11b (when not connected), the insulation inspection apparatus 1 is operated, and the operation unit 8 performs the processing on the processing unit 5. The operation instruction to execute the steady value storage process is input. In this example, as an example, an operation instruction is input during a warm-up period after power-on of the insulation inspection apparatus 1 (a predetermined period immediately after power-on), and the processing unit 5 performs a steady-state storage process. In the steady value storage process, first, the processing unit 5 executes control on the power supply unit 3 to output the DC voltage V1 from the power supply unit 3 in a stepped manner. The DC voltage V1 is applied between the probes 2a, 2b, thereby, flows to the ground leakage current _{I L} through the probe 2a, 2b and ammeter 4. In this case, the leakage current I _L, the output resistance 3a and each probe 2a of the power supply unit 3, the leakage current I _LC flowing to the ground through a stray capacitance Cs which exists between 2b, the output resistance 3a and each probe It becomes a combined current with a leakage current I _LRp (constant) flowing to the ground via the insulation resistance Rp existing between 2a and 2b. Specifically, the waveform of the leakage current I _L, the transient response waveform (i.e., as shown by a broken line in FIG. 2, the current value becomes temporarily large immediately after application of the DC voltage V1, then charge the stray capacitance Cs Current value gradually decreases as time elapses (as time elapses), and leakage current I _LRp (when the elapsed time from application of DC voltage V1 reaches time t1) when charging of stray capacitance Cs is completed (time t1). = 0.1 μA (= waveform with only 100 V / 1 GΩ).

The ammeter 4 measures the leakage current _IL at a predetermined sampling period, and outputs data Di indicating the current value. Processing section 5 inputs the data Di, while detecting the current value of the leakage current I _L, flows when it becomes substantially constant current value (when it becomes only the leakage current I _LRP) steadily It is stored in the storage unit 6 as a steady value _IL0 that is a current value. Finally, the processing unit 5 controls the power supply unit 3 to stop the output of the DC voltage V1. Thereby, the steady value storage process is completed. As a result, each time the insulation inspection apparatus 1 is activated, the steady value _IL0 corresponding to the ambient environment at the time of activation is stored in the storage unit 6.

Next, in a state where the probe 2a is connected to the wiring pattern 11a and the probe 2b is connected to the wiring pattern 11b (connected state), the operation unit 8 instructs the processing unit 5 to perform an inspection process. input. In this inspection process, the processing unit 5 executes the control on the power supply unit 3 again, and outputs the DC voltage V1 in a step shape. This DC voltage V1 is applied between the probes 2a and 2b and between the wiring patterns 11a and 11b, so that the leakage current _IL is grounded via the probes 2a and 2b, the wiring patterns 11a and 11b and the ammeter 4. Flowing into. In this case, the leakage current I _L includes the leakage current I _LC that flows to the ground via the stray capacitance Cs, the leakage current I _LRp (constant) that flows to the ground via the insulation resistance Rp, the output resistance 3a, and This is a combined current with a leakage current I _LRx (constant: (= 0.2 μA (= 100 V / 500 MΩ)) that flows to the ground via the insulation resistance Rx between the wiring patterns 11 a and 11 b. Specifically, the waveform of the leakage current I _L, the transient response waveform as shown by a solid line in FIG. 2 (i.e., the current value becomes temporarily large immediately after application of the DC voltage V1, it is then charged to the floating capacitance Cs (A waveform in which the current value gradually decreases as time _progresses, and only the combined current (constant) of the leakage current I _LRp and the leakage current I _LRx is obtained when charging of the stray capacitance Cs is completed (time t1)) It becomes. Actually, there is some stray capacitance between the wiring patterns 11a and 11b. However, since the wiring patterns 11a and 11b are sufficiently shorter than the probes 2a and 2b, this stray capacitance is stray between the probes 2a and 2b. It is extremely small compared with the capacity Cs. For this reason, the stray capacitance between the wiring patterns 11a and 11b is not considered in order to facilitate understanding of the invention.

Processing section 5, each for detecting a current value of the leakage current I _L to input data Di output from the ammeter 4, while subtracting the constant value I _L0 stored from the current value in the memory unit 6 Then, the current value after subtraction is compared with the threshold value I _Lth (1 μA) stored in the storage unit 6. As a result of this comparison, when the current value after subtraction is equal to or less _{than the} threshold value _ILth , the processing unit 5 determines that the insulation between the wiring patterns 11a and 11b is at a sufficient level (no insulation failure has occurred). To do. In this case, as shown in FIG. 3, not subtract the constant value I _L0 leakage current than I _L time waveform is equal to or less than the threshold I _Lth of t2, the waveform of the leakage current I _L obtained by subtracting the constant value I _L0 threshold since the direction of I _Lth hereinafter become time t3 arrives early stationary value _{I L0} towards the method of comparing the waveform with a threshold value _{I Lth} leakage current _{I L} obtained by subtracting the leakage current _{I L} of the waveform threshold value I It can be quickly determined whether or not _Lth or less. Accordingly, the inspection processing time for the wiring patterns 11a and 11b is shortened.

On the other hand, the leakage when the wiring pattern 11a, the insulation failure between 11b has occurred, because the current value of the leakage current I _L is increased, even when reaching the time t3, which is obtained by subtracting the constant value I _L0 situation that the waveform of the current _{I L} does not become less than the threshold value _{I Lth} occurs. Thus, in this inspection process, when the waveform of the leakage current I _L obtained by subtracting the constant value I _L0 is also greater than the threshold I _Lth reached time t3, the processing unit 5, the wiring patterns 11a, insulation failure between 11b Is determined to have occurred. The processing unit 5 stores the result of the inspection process in the storage unit 6. Thereby, the inspection process is completed. Finally, the processing unit 5 causes the output unit 7 to output the result of the inspection process stored in the storage unit 6. Thereby, the insulation inspection process is completed.

In addition, once the steady value _IL0 is measured, by using the steady value _IL0 , the inspection process can be repeated without executing the steady value storage process again. Therefore, the time can be further shortened by the amount that can eliminate the time-consuming steady value storage process.

Thus, in this insulation inspection process and insulation inspection apparatus 1, the processing unit 5 uses the ammeter 4 when the DC voltage V1 is applied between the probes 2a and 2b when the wiring patterns 11a and 11b are not connected. the steady-state value I _L0 of the measured leakage current I _L is measured, the wiring patterns 11a, leakage current each probe 2a in the connection state of the 11b, the DC voltage V1 between 2b is measured by the ammeter 4 when applied while subtracting the constant value I _L0 from I _L, by comparing the current value and the threshold value I _Lth obtained by the subtraction, examining the quality of the insulation between the probe 2a, 2b. Therefore, according to this insulation inspection process and insulation inspection apparatus 1, the steady value I _L0 is measured and stored in advance, so that when there is no insulation failure between the wiring patterns 11a and 11b, the steady value I since the leakage current I _L by the amount obtained by subtracting the _L0 reaches quickly the threshold I _Lth, it is possible to wiring patterns 11a, an insulating state between 11b inspecting the shorter time to be good.

In addition, according to the insulation inspection apparatus 1, the processing unit 5 performs the steady value storage process during the warm-up period (a predetermined period immediately after the power is turned on) after the insulation inspection apparatus 1 is turned on. With respect to the steady-state value I _L0 that is likely to change depending on the environment, a new steady-state value I _L0 corresponding to the surrounding environment at the start-up can be stored in the storage unit 6 each time the insulation inspection apparatus 1 is started. The accuracy of the insulation inspection can be improved by using _IL0 .

In addition, this invention is not limited to said structure. For example, a jig-type insulation inspection device having a plurality (3 or more) of probes (equipped with a plurality of probes corresponding to a plurality of inspection objects, and continuously performing insulation inspection processing on the plurality of inspection objects) Of course, it can be applied to an insulation inspection apparatus). In addition, the wiring patterns 11a and 11b formed on the circuit board are described as examples of the inspection object, but the inspection object is not limited to this, and the insulation resistance of various objects can be inspected. Further, although the example in which the steady value storage process is executed during the warm-up period after turning on the power has been described above, the invention is not limited to this, and the period during which the insulation inspection apparatus 1 does not perform the inspection process on the circuit board (the present invention). Non-execution of inspection in step 1. For example, when the circuit board is transported to the insulation inspection apparatus 1 and is periodically executed (between inspection processing and inspection processing), Every time a predetermined number of circuit boards have been inspected, or every time a predetermined time has elapsed since the execution of the previous steady value storage process (or a predetermined time has arrived) You can also do it every time. As a result, since the steady value _IL0 that is likely to change depending on the surrounding environment such as humidity can be stored in the storage unit 6 in correspondence with the constantly changing ambient environment, the accuracy of the insulation test using the steady value _IL0 is improved. This can be further improved.

In addition, the configuration in which an operation instruction is input from the operation unit 8 to the processing unit 5 has been described above. However, whether or not the processing unit 5 is in the warm-up period immediately after the power is turned on, or the insulation inspection processing for the circuit board is not performed. It is determined whether it is time, whether inspection for a predetermined number of circuit boards is completed, or whether a predetermined time has elapsed since the execution of the previous steady value storage process, and the steady value storage process It is also possible to adopt a configuration that executes automatically. According to this configuration, the stored value in the storage unit 6 can be automatically updated in response to a change in the surrounding environment for the steady-state value I _L0 that easily changes depending on the surrounding environment such as humidity. The accuracy can be improved reliably.

1 is a configuration diagram showing a configuration of an insulation inspection device 1. Each probe 2a, a waveform diagram of a leakage current _{I L} flowing between 2b. It is an enlarged waveform diagram in the vicinity time t2 of the leakage current I _L.

Explanation of symbols

1 insulation test apparatus 2a, 2b probe 3 power supply unit 4 ammeter 5 processor 6 storage section 11a, 11b wiring patterns I _L leakage current I _L0 constant value Rx insulation resistance V1 DC voltage

Claims (9)

A DC voltage is applied between the pair of probes connected to the inspection object, and the inspection object is based on a current value of a leakage current flowing through the pair of probes in a state where the DC voltage is applied and a predetermined threshold value. An insulation inspection method for inspecting an insulation state of a body,
Measure the steady value of the leakage current when the DC voltage is applied between the pair of probes in the unconnected state of the inspection object,
When the inspection object is connected between the pair of probes and the insulation state is inspected, the current value measured while measuring the current value of the leakage current in the DC voltage application state An insulation inspection method for subtracting the steady value from the value and inspecting the insulation state based on the current value obtained by the subtraction and the threshold value.   The insulation inspection method according to claim 1, wherein the measurement of the steady value is periodically performed when the insulation state inspection is not performed.   The insulation inspection method according to claim 2, wherein the steady-state value is measured at predetermined time intervals.   The insulation inspection method according to claim 1, wherein the measurement of the steady value is executed every time the inspection of the insulation state for a predetermined number of the inspection objects is completed. A pair of probes connected to the object to be examined;
A power supply unit for applying a DC voltage between the pair of probes;
A current measurement unit that measures a current value of a leakage current flowing through the pair of probes in the application state of the DC voltage;
An insulation inspection apparatus comprising a processing unit that inspects an insulation state of the inspection object based on a current value of the measured leakage current and a predetermined threshold value,
The processing unit stores a steady value of the leakage current measured by the current measuring unit when the DC voltage is applied between the pair of probes from the power supply unit in a state where the inspection object is not connected. The current value for the leakage current to the current measuring unit when the DC voltage is applied between the pair of probes from the power source unit in the connection state of the inspection object. An insulation inspection apparatus that subtracts the steady value from the measured current value while performing measurement, and performs an inspection process for inspecting the insulation state based on the current value obtained by the subtraction and the threshold value.   The insulation inspection apparatus according to claim 5, wherein the processing unit executes the steady value storage processing within a predetermined period immediately after power-on.   The insulation inspection apparatus according to claim 5, wherein the processing unit periodically executes the steady value storage processing when the inspection processing is not executed.   The insulation inspection apparatus according to claim 7, wherein the processing unit executes the steady value storage process at predetermined time intervals.   The insulation inspection apparatus according to claim 5, wherein the processing unit executes the steady value storage processing every time the inspection processing for a predetermined number of the inspection objects is completed.

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