A conductive slip ring insulation resistance defect accelerated testing device and method

Abstract

The present invention discloses an accelerated test device and method for insulation resistance defects of a conductive slip ring. The device comprises a sampling resistor and a current limiting resistor, a first switch matrix comprising N single-pole double-throw switches, a second switch matrix comprising two N-to-1 switches, a high-voltage excitation source, a voltage sampling unit, and a control unit. When the device is used to measure the conductive slip ring, N-1 branches are connected in parallel and a pressurization operation is performed through the first switch matrix, and then the fast measurement of the insulation impedance of the N-1 branches is achieved through the second switch matrix. Since the number of pressurization times is reduced, the present invention can effectively reduce the overall insulation resistance measurement time of the conductive slip ring and improve the product detection efficiency.

Description

Technical Field

[0001] The invention belongs to the field of testing instruments, and in particular relates to a conductive slip ring insulation resistance defect accelerated testing device and method. Background Art

[0002] Conductive slip ring is an electrical product used for electrical connection of relatively rotating structures to solve the problem of wire winding when unlimited rotation is required. There are many types of conductive slip rings, including through-hole conductive slip rings, cap-type conductive slip rings, micro conductive slip rings, Ethernet conductive slip rings, plug-in conductive slip rings, etc., which are widely used in security, power, instruments and other fields.

[0003] Conductive slip ring devices generally have several to dozens of slip rings installed on cylindrical insulating materials. The insulation strength between the slip rings has an important influence on its withstand voltage performance. Slip ring short circuits and slip ring material defects, such as cracks and holes during glue filling, may lead to a decrease in the insulation performance of conductive slip ring devices. In order to detect the insulation resistance or withstand voltage capability of conductive slip ring products, insulation resistance testers or insulation withstand voltage testers are traditionally used to test the insulation impedance between each ring. During the test, the tester connects the taps of the two slip rings being tested and applies a voltage between the two rings according to the withstand voltage index requirements of the product. In this case, the insulation resistance between the two rings is measured, and the insulation resistance value should be greater than the specified value (such as 10MΩ). For devices with multiple slip rings, the insulation resistance between each two slip rings should meet the requirements.

[0004] With the development of technology, the number of loops in the current conductive slip ring device can reach dozens to hundreds. However, the increase in the number of loops leads to an exponential increase in the number of tap combinations that need to be tested. For example, a 10-loop conductive slip ring only needs to test The insulation resistance value of the group, while the 100-ring conductive slip ring needs to be tested The sharp increase in the test volume leads to a decrease in the test efficiency of the conductive slip ring, which ultimately affects the production efficiency. Summary of the invention

[0005] Aiming at the problem of low test efficiency of current conductive slip rings, the present invention provides a conductive slip ring insulation resistance defect accelerated test device and method.

[0006] The device involved in the present invention comprises a sampling resistor, a current limiting resistor, a first switch matrix and a second switch matrix each comprising N single-pole single-throw switches, a high-voltage excitation source, a voltage sampling unit, and a control unit.

[0007] The switches in the first switch matrix and the switches in the second switch matrix are first connected in series in pairs, and the N series connection points are respectively connected to the N taps of the slip ring; the non-series ends of all the switches in the first switch matrix are connected to one point, and the point is connected to the first output end of the high-voltage excitation source; the non-series points of all the switches in the second switch matrix are connected to one point, and the point is connected to the second output end of the high-voltage excitation source after passing through the series current limiting resistor and the sampling resistor;

[0008] The input end of the voltage sampling unit is connected in parallel to both ends of the sampling resistor;

[0009] The control unit is respectively connected to the control end of the first switch matrix, the control end of the second switch matrix and the control end of the voltage sampling unit through a digital control bus.

[0010] Preferably, the single-pole single-throw switches in the first switch matrix and the second switch matrix are relays or analog switches.

[0011] Preferably, the high-voltage excitation source is a high-voltage package, and the reference potential of the high-voltage excitation source is connected to the reference potential of the sampling unit.

[0012] Preferably, the digital control bus includes an isolator.

[0013] The method involved in the present invention comprises the following steps:

[0014] Among all the taps of the conductive slip ring, take one branch as an independent tap, and short-circuit the remaining taps to one point; measure the insulation resistance between the independent tap and the short-circuit point of the remaining taps;

[0015] Take each tap as an independent tap in turn, measure the insulation resistance between it and the short-circuit point of the remaining taps, and obtain a measurement result equal to the number of taps;

[0016] Check whether all measured insulation resistance values ​​are greater than R th / (N-1), if yes, the test is over, indicating that there is no defect in the insulation resistance of the conductive slip ring; otherwise, select the one with a resistance lower than R th / (N-1) The tap corresponding to the measurement result is recorded as M, which is the tap to be measured in the next step, where R th is the insulation resistance threshold between any two taps of the slip ring;

[0017] Take any one tap from the taps to be tested as an independent tap, and divide the remaining taps from the taps to be tested into two groups, one of which has P taps and the other has Q taps, and the taps in the same group are short-circuited respectively.

[0018] Measure the insulation resistance between the independent tap and the two groups of short-circuit points in turn, and compare them with the reference value R th / P and R th / Q comparison. Take the taps included in the short-circuit points corresponding to the measurement results lower than the reference value, divide them into two groups, short-circuit them separately, and measure the insulation resistance between the independent taps and the two groups of short-circuit points.

[0019] Continue to group, measure, and compare according to the measurement results until only one tap is left at the short-circuit point after grouping and its insulation resistance value is less than R th , then the insulation resistance between the taps on both sides corresponding to the insulation resistance value is determined as the fault resistance.

[0020] According to the above steps, all the taps are selected in turn as independent taps among the M taps to be tested, and all the fault resistors are determined and located.

[0021] Preferably, a specific implementation method of taking a tap as an independent tap is: sending a control signal through the control unit to drive the switch connected to the tap in the first switch matrix to turn on, and disconnect the remaining switches.

[0022] Preferably, a specific implementation method of short-circuiting a group of taps is: sending a control signal through the control unit to drive the switches connected to the group of taps in the second switch matrix to turn on, and disconnecting the remaining switches.

[0023] Preferably, the specific implementation method of measuring the insulation resistance between the tap and the short-contact point is: sampling the voltage across the sampling resistor through the voltage sampling unit, and the controller reads the sampling data and calculates the insulation resistance value according to the following formula:

[0024]

[0025] Where Uo is the output voltage value of the high-voltage excitation source, Us is the voltage across the sampling resistor, and Rs is the sampling resistor value.

[0026] Beneficial effects of the present invention: The present invention can effectively reduce the overall time of insulation resistance measurement of the conductive slip ring by reducing the number of pressurization times, thereby improving product detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the schematic diagram of the accelerated test device for insulation resistance defects of conductive slip rings.

[0028] Figure 2 The figure is a flow chart of the accelerated testing method for insulation resistance defects of conductive slip rings. DETAILED DESCRIPTION

[0029] To facilitate understanding of the solution and effects of the embodiments of the present invention, a specific application example is given below. Those skilled in the art should understand that this example is only for facilitating understanding of the present invention, and any specific details thereof are not intended to limit the present invention in any way.

[0030] like Figure 1 As shown, in this embodiment, the product line used by the conductive slip ring insulation resistance defect accelerated test device is a 6-tap conductive slip ring, the test voltage is 250V, and the insulation resistance between any two taps of the conductive slip ring shall not be less than 10MΩ.

[0031] In the device of this embodiment, the resistance ratio of the sampling resistor and the current limiting resistor is determined by the test voltage and the input range of the voltage sampling unit. When the high-voltage excitation source is 250V and the input range of the voltage sampling unit is ±5V, the ratio of the sampling resistor to the current limiting resistor should not exceed 1:49, so as to ensure that the input signal of the voltage sampling unit does not exceed the measurement limit. At the same time, considering that the effective resolution of the input signal should be as high as possible, the sampling resistor and the current limiting resistor values ​​are determined to be 560Ω and 30kΩ respectively.

[0032] The first switch matrix and the second switch matrix each contain 6 single-pole single-throw switches, and the switch selection is a single-pole single-throw reed high-voltage relay with a withstand voltage of more than 300V. The switches in the first switch matrix and the switches in the second switch matrix are first connected in series in pairs, and 6 terminals are led out at the series connection point to connect the 6 taps of the tested conductive slip ring. The non-series ends of all relays in the first switch matrix are connected to one point, and then connected to the first output end of the 250V high-voltage package; the non-series points of all relays in the second switch matrix are connected to one point, and then connected in series with the current limiting resistor and the sampling resistor in turn, and finally connected to the second output end of the high-voltage package.

[0033] The voltage sampling unit is composed of an input protection circuit, a filter, and a 10-bit bipolar ADC. The reference ground of the voltage sampling unit is connected to the second output terminal of the high-voltage package (i.e., the power ground), and its output signal is connected to the control unit via the SPI digital bus and 4N25 optocoupler isolation. The control ends of the 6-way relays of the first switch matrix and the second switch matrix are driven by a ULN2803 Darlington tube array chip, and the input signal of the chip is connected to the control unit after being isolated by a 4N25 optocoupler. The maximum isolation voltage across the 4N25 optocoupler is 5000V, which effectively protects the control unit from the risk of high-voltage shock.

[0034] The process of using the device of this embodiment to test a certain conductive slip ring is as follows: Figure 2 As shown:

[0035] Set the insulation impedance qualified threshold R between any two taps of the slip ring th is 10MΩ.

[0036] Connect all the taps of the slip ring to the device, and number the taps 1 to 6 according to the wiring sequence. Under the control of the control unit, the relay connected to the first tap in the first switch matrix is ​​driven to close, while the other five relays are disconnected, so that the branch where the first tap is located is used as an independent tap; under the control of the control unit, the relay connected to the first tap in the second switch matrix is ​​driven to open and the other six relays are closed, so that the 2nd to 6th taps are short-circuited to one point.

[0037] The insulation resistance is then measured between the individual taps and the shorted point of the remaining taps.

[0038] According to the above method, each tap is taken as an independent tap in turn, and the insulation resistance value between it and the short-circuit point of the remaining taps is measured to obtain a measurement result equal to the number of taps, as shown in Table 1.

[0039] Table 1 The first round of measurement data

[0040]

[0041] calculate:

[0042]

[0043] According to Table 1, select less than 2×10 6 The 1st, 2nd, 5th and 6th taps corresponding to Ω, the total number of selected taps M=4.

[0044] The first tap is selected as an independent tap from the selected taps to be tested, and the remaining taps in the taps to be tested are divided into two groups, one group is the second tap, and the other group is the fifth and sixth taps. Under the condition of keeping the state of the first switch matrix unchanged, the control unit first drives the relay connected to the second tap in the second switch matrix to close and disconnect the other five relays, and measures the insulation resistance at this time; then drives the relay connected to the fifth and sixth taps in the second switch matrix to close and disconnect the other four relays, that is, short-circuit the fifth and sixth taps, and measures the insulation resistance at this time, and obtains two groups of measurement results, as shown in Table 2.

[0045] Table 2 The first round of measurement data of the first tap as an independent tap

[0046] Combined with the 1st tap 2nd tap The 5th and 6th taps are short-circuited Insulation resistance measurement value (Ω) <![CDATA[3.00×10 11 ]]> <![CDATA[1.24×10 6 ]]>

[0047] Calculate separately:

[0048]

[0049] Compare the data in Table 2 with the above data. The measurement results of the 5th and 6th taps are lower than the reference values, so they should be divided into two groups.

[0050] Divide it into two groups, and measure the insulation resistance between the first tap and the two groups of short-circuit points again. The two groups of measurement results are shown in Table 3.

[0051] Table 3 The second round of measurement data of the first tap as an independent tap

[0052] Combined with the 1st tap 5th tap 6th tap Insulation resistance measurement value (Ω) <![CDATA[1.24×10 6 ]]> <![CDATA[3.10×10 11 ]]>

[0053] According to the above calculation method, the reference values ​​of the two groups are 1×1 7 Ω, compared with the data in Table 3, the measurement result of the 5th tap is lower than the reference value.

[0054] Therefore, in the test of the 1st tap as an independent tap, it can be determined that there is a defect between the 1st tap and the 5th tap, and the insulation resistance value is about 1.24MΩ.

[0055] Then, the 2nd tap is used as an independent tap for testing. The remaining 5th tap and 6th tap are divided into two groups, and the two groups of measurement results are shown in Table 4.

[0056] Table 4 The first round of measurement data of the second tap as an independent tap

[0057] Combined with the 2nd tap 5th tap 6th tap Insulation resistance measurement value (Ω) <![CDATA[3.20×10 11 ]]> <![CDATA[2.00×10 3 ]]>

[0058] According to the above calculation method, the reference values ​​of the two groups are 1×10 7 Ω, compared with the data in Table 4, the measurement result of the 6th tap is lower than the reference value.

[0059] Therefore, in the test of the second tap as an independent tap, it can be determined that there is a defect between the first tap and the fifth tap, and the insulation resistance value is about 0.002MΩ.

[0060] Then, the 5th tap is used as an independent tap for testing. At this time, only the 6th tap is left, and the group measurement results are shown in Table 5.

[0061] Table 5 The first round of measurement data of the 5th tap as an independent tap

[0062] Combined with the 5th tap 6th tap Insulation resistance measurement value (Ω) <![CDATA[6.50×10 11 ]]>

[0063] According to the above calculation method, the reference values ​​of the two groups are 1×10 7 Ω, compared with the data in Table 5, the measurement result of the 6th tap is higher than the reference value.

[0064] In summary, it can be determined that there is a defect between the 1st tap and the 5th tap, and the insulation resistance value is about 1.24MΩ; there is a defect between the 2nd tap and the 6th tap, and the insulation resistance value is about 0.002MΩ.

Claims

1. A conductive slip ring insulation resistance defect accelerated testing method, using a conductive slip ring insulation resistance defect accelerated testing device, including a sampling resistor, a current limiting resistor, a first switch matrix and a second switch matrix each including N single-pole single-throw switches, a high-voltage excitation source, a voltage sampling unit, and a control unit; The switches in the first switch matrix and the switches in the second switch matrix are first connected in series in pairs, and the N series connection points are respectively connected to the N taps of the slip ring; the non-series ends of all the switches in the first switch matrix are connected to one point, and the point is connected to the first output end of the high-voltage excitation source; the non-series points of all the switches in the second switch matrix are connected to one point, and the point is connected to the second output end of the high-voltage excitation source after passing through the series current limiting resistor and the sampling resistor; The input end of the voltage sampling unit is connected in parallel to both ends of the sampling resistor; The control unit is respectively connected to the control end of the first switch matrix, the control end of the second switch matrix and the control end of the voltage sampling unit through a digital control bus; Features: The method comprises the following steps: Among all the taps of the conductive slip ring, take one branch as an independent tap, and short-circuit the remaining taps to one point; measure the insulation resistance between the independent tap and the short-circuit point of the remaining taps; Take each tap as an independent tap in turn, measure the insulation resistance between it and the short-circuit point of the remaining taps, and obtain a measurement result equal to the number of taps; Check whether all measured insulation resistance values ​​are greater than R th / (N-1), if yes, the test is over, indicating that there is no defect in the insulation resistance of the conductive slip ring; otherwise, select the one with a resistance lower than R th / (N-1) The tap corresponding to the measurement result is recorded as M, which is the tap to be measured in the next step, where R th is the insulation resistance threshold between any two taps of the slip ring; Take any one of the taps to be tested as an independent tap, and divide the remaining taps in the taps to be tested into two groups, one of which has P taps and the other has Q taps, and the taps in the same group are short-circuited respectively; Measure the insulation resistance between the independent tap and the two groups of short-circuit points in turn, and compare them with the reference value R th / P and R th / Q comparison; take the taps included in the short-circuit points corresponding to the measurement results lower than the reference value, divide them into two groups and short-circuit them separately, and measure the insulation resistance between the independent taps and the two groups of short-circuit points; Continue to group, measure, and compare according to the measurement results until only one tap is left at the short-circuit point after grouping and its insulation resistance value is less than R th , then the insulation resistance between the taps on both sides corresponding to the insulation resistance value is determined as the fault resistance; According to the above steps, all the taps are selected in turn as independent taps among the M taps to be tested, and all the fault resistors are determined and located.

2. The method for accelerating the testing of insulation resistance defects of a conductive slip ring according to claim 1, characterized in that: The specific implementation method of taking a tap as an independent tap is: sending a control signal through the control unit to drive the switch connected to the tap in the first switch matrix to turn on, and disconnect the remaining switches.

3. The method for accelerating the testing of insulation resistance defects of a conductive slip ring according to claim 1, characterized in that: The specific implementation method of short-circuiting a group of taps is: sending a control signal through the control unit to drive the switches connected to the group of taps in the second switch matrix to turn on, and disconnecting the remaining switches.

4. A conductive slip ring insulation resistance defect accelerated testing method according to any one of claims 1 to 3, characterized in that: The specific implementation method of measuring the insulation resistance between the tap and the short-contact point is: the voltage across the sampling resistor is sampled by the voltage sampling unit, and the controller reads the sampled data and calculates the insulation resistance value according to the following formula: Where Uo is the output voltage value of the high-voltage excitation source, Us is the voltage across the sampling resistor, and Rs is the sampling resistor value.

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