CN212391567U - Electrified testing arrangement of high tension cable ground connection defect - Google Patents
Electrified testing arrangement of high tension cable ground connection defect Download PDFInfo
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- CN212391567U CN212391567U CN202021760022.5U CN202021760022U CN212391567U CN 212391567 U CN212391567 U CN 212391567U CN 202021760022 U CN202021760022 U CN 202021760022U CN 212391567 U CN212391567 U CN 212391567U
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Abstract
The utility model discloses an electrified testing arrangement of high tension cable ground connection defect, its characterized in that: the device comprises a direct current charging circuit, a voltage measuring device and a change-over switch; the direct current charging circuit comprises a direct current source and a current measuring device which are connected in series; two ends of the direct current charging circuit are respectively externally connected with two phase tail pipes at the local end; the current measuring device is used for measuring the current of a tail pipe connected with the direct current charging circuit; one end of the voltage measuring device is externally connected with the residual phase tail pipe at the local end, and the other end of the voltage measuring device is connected with the direct current charging circuit through the change-over switch; through change over switch's switching, voltage measurement device measures each tail pipe that direct current charging circuit even to the voltage between the corresponding earthing terminal, the utility model discloses reduce the number of times of charging, shortened test time, improved efficiency of software testing, high-efficient and nimble, have good application prospect.
Description
Technical Field
The utility model relates to an electrified testing arrangement of high tension cable ground connection defect belongs to power transmission and transformation equipment technical field.
Background
The grounding connection defect of the high-voltage cable easily causes the grounding failure of a metal shield of the cable, and easily causes the suspension discharge of a metal sheath and an insulation shield and damages the insulation, thereby causing the fault of the cable. The live testing method for the on-site loop resistance needs to test through-flow charging for 3 times, has low testing efficiency and cannot meet the requirement of on-site rapid testing.
SUMMERY OF THE UTILITY MODEL
The utility model provides an electrified testing arrangement of high tension cable ground connection defect has solved that current test method algorithm is complicated, and efficiency of software testing is low, can't satisfy the problem of on-the-spot quick test demand.
In order to solve the technical problem, the utility model discloses the technical scheme who adopts is:
a high-voltage cable grounding connection defect live-line testing device comprises a direct-current charging circuit, a voltage measuring device and a change-over switch;
the direct current charging circuit comprises a direct current source and a current measuring device which are connected in series; two ends of the direct current charging circuit are respectively externally connected with two phase tail pipes at the local end; the current measuring device is used for measuring the current of a tail pipe connected with the direct current charging circuit;
one end of the voltage measuring device is externally connected with the residual phase tail pipe at the local end, and the other end of the voltage measuring device is connected with the direct current charging circuit through the change-over switch; through the switching of the selector switch, the voltage measuring device measures the voltage between each tail pipe connected with the direct current charging circuit and the corresponding grounding terminal.
Both ends of the direct current charging circuit and the voltage measuring device are connected with the tail pipe through the current limiting device.
The voltage measured by the voltage measuring device is equal to the voltage of the current limiting device plus the voltage between the tail pipe connected with the current limiting device and the corresponding grounding terminal.
The change-over switch is a single-pole double-throw switch, the moving end of the single-pole double-throw switch is connected with the voltage measuring device, and the two static ends of the single-pole double-throw switch are respectively connected with the two ends of the direct-current charging circuit.
The current limiting device is a metal coil or a resistor.
The direct current source is a storage battery power supply or a constant current source with an output current ripple coefficient not more than 0.1%.
The accuracy of the current measuring device and the accuracy of the voltage measuring device are not lower than 0.2 level.
The utility model discloses the beneficial effect who reaches: the utility model discloses the application direct current source charges (pours into direct current into promptly) the cable tail pipe, and twice charges can be according to current measuring device measuring electric current and voltage measuring device measuring voltage to obtain every looks tail pipe to the resistance between corresponding earthing terminal, judge out the cable tail pipe according to the resistance and to correspond whether defect between the earthing terminal, reduced the number of times of charging, shortened test time, improved efficiency of software testing, high efficiency and nimble have good application prospect.
Drawings
FIG. 1 is a schematic diagram of a cable grounding system;
FIG. 2 is a connection diagram of a cable grounding system;
FIG. 3 is an equivalent circuit diagram of a cable grounding system;
fig. 4 is a schematic structural diagram of the device of the present invention.
Detailed Description
The present invention will be further described with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
As shown in fig. 1, 2 and 3, the cable grounding system comprises a home terminal three-phase tail pipe, a three-phase metal sheath, an opposite terminal three-phase tail pipe and a three-phase copper bar; the tail pipe of the phase A at the local end, the metal sheath of the phase A, the tail pipe of the phase A at the opposite end and the copper bar of the phase A are sequentially connected in series, and the tail end of the copper bar of the phase A is a grounding end and is directly grounded; the tail pipe of the B phase at the main end, the metal sheath of the B phase, the tail pipe of the B phase at the opposite end and the copper bar of the B phase are sequentially connected in series, and the tail end of the copper bar of the B phase is a grounding end and is directly grounded; the tail pipe of the C phase at the home terminal, the metal sheath of the C phase, the tail pipe of the C phase at the opposite terminal and the copper bar of the C phase are sequentially connected in series, and the tail end of the copper bar of the C phase is a grounding terminal and is directly grounded.
Testing the grounding connection defect of the high-voltage cable by measuring whether the resistance between each phase of tail pipe and the corresponding grounding end is abnormal or not; therefore, the adopted high-voltage cable is connected with the defect live-line testing device in a grounding mode and comprises a direct-current charging circuit, a voltage measuring device and a change-over switch.
The direct current charging circuit comprises a direct current source and a current measuring device which are connected in series; two ends of the direct current charging circuit are respectively externally connected with two phase tail pipes at the local end; the current measuring device is used for measuring the current of a tail pipe connected with the direct current charging circuit; one end of the voltage measuring device is externally connected with the residual phase tail pipe at the local end, and the other end of the voltage measuring device is connected with the direct current charging circuit through the change-over switch; through the switching of the selector switch, the voltage measuring device measures the voltage between each tail pipe connected with the direct current charging circuit and the corresponding grounding terminal.
The specific structure of the device is shown in fig. 4, and comprises a direct current charging circuit, a voltage measuring device, a change-over switch, two current limiting devices and three clamps.
The direct current source and the current measuring device are connected in series to form a direct current charging circuit; in order to limit the influence of tail pipe induced voltage on test equipment (namely a voltage measuring device and a current measuring device), two ends of a direct current charging circuit and the voltage measuring device are connected with tail pipes through current limiting devices, the current limiting devices are externally connected with the tail pipes through clamps, the other ends of the voltage measuring devices are connected with two ends of the direct current charging circuit through change-over switches, and voltage measured by the voltage measuring devices is equal to the sum of the voltage of the current limiting devices and the voltage between the tail pipes connected with the current limiting devices and corresponding grounding ends (namely the voltage of the current limiting devices, the voltage of the corresponding single-phase tail pipes, the voltage of the corresponding metal sheaths and the voltage of.
The direct current source adopts a storage battery power supply or a constant current source with the output current ripple coefficient not more than 0.1 percent; the current limiting device adopts a metal coil or a resistor, and the resistance value is not less than 1k omega; the precision of the current measuring device and the precision of the voltage measuring device are not lower than 0.2 level, and the current measuring device and the voltage measuring device respectively adopt a current meter and a voltmeter; the change-over switch is a single-pole double-throw switch, the moving end of the single-pole double-throw switch is connected with the voltage measuring device, and the two static ends of the single-pole double-throw switch are respectively connected with the two ends of the direct-current charging circuit.
The current limiting device is defined as a first current limiting device, a second current limiting device and a third current limiting device, and the three clamps are defined as a first clamp, a second clamp and a third clamp, and the specific structure of the device is as follows:
the device comprises a first clamp, a first current limiting device, a current measuring device, a direct current source, a second current limiting device and a second clamp which are sequentially connected in series (of course, the positions of the current measuring device and the direct current source can be exchanged), a simplest single-pole double-throw switch is adopted as a change-over switch, one end of a voltage measuring device sequentially passes through a third current limiting device and a residual phase tail pipe which is externally connected with the third clamp, the other end of the voltage measuring device is connected with a moving end of the single-pole double-throw switch, two static ends of the single-pole double-throw switch are respectively connected with the first current limiting device and the second current limiting device, and the voltage measuring device measures the total voltage of the first current limiting device, the corresponding tail pipe, the corresponding metal sheath and the corresponding copper bar or the total voltage of the second current limiting device, the corresponding tail pipe, the corresponding metal sheath and the corresponding copper bar. For example, the first clamp and the second clamp are respectively connected with the tail pipes of the phases A and B, and the voltage measuring device measures and measures the sum of the tail pipe voltage of the phase A at the local end, the metal sheath voltage of the phase A, the tail pipe voltage of the phase A at the opposite end and the copper bar voltage of the phase A, or the sum of the tail pipe voltage of the phase B at the local end, the metal sheath voltage of the phase B, the tail pipe voltage of the phase B at the opposite end and the copper bar voltage of the phase B.
The process of testing the cable grounding connection by the device is as follows:
step 1, connecting the high-voltage cable grounding connection defect live-line testing device with a local end three-phase tail pipe, and outputting direct current by a direct current source of a direct current charging circuit.
And connecting the direct current charging circuit with any two phases of tail pipes, connecting the voltage measuring device with the rest one phase of tail pipe, and applying direct current for stabilization.
And 2, calculating the resistance value between each tail pipe connected with the direct current charging circuit and the corresponding grounding end according to the current measured by the current measuring device and the voltage measured by the voltage measuring device.
During measurement, the resistance of the current measuring device is equivalent to 0, the resistance measured by the voltage measuring device is equivalent to infinity, therefore, through the switching of the selector switch, the voltage between each tail pipe connected with the direct current charging circuit and the corresponding grounding end is measured by the voltage measuring device, the resistance value between each tail pipe and the corresponding grounding end can be obtained by applying ohm law according to the voltage and the current, and the process can be directly obtained through manual calculation.
And 3, adjusting two tail pipes connected with the direct current charging circuit to ensure that the tail pipes connected at this time are different from the tail pipes connected at the first time.
And 4, calculating the resistance value between the residual phase tail pipe at the local end and the corresponding grounding end according to the current measured by the current measuring device and the voltage measured by the voltage measuring device, wherein the process can also be obtained by manual direct calculation.
Step 5, judging the grounding connection defect of the high-voltage cable in response to that the resistance value between any single-phase tail pipe and the corresponding grounding terminal is larger than a first threshold value, or the ratio of the resistance values between any two phase tail pipes and the corresponding grounding terminal exceeds a second threshold value and the maximum resistance value between the single-phase tail pipe and the corresponding grounding terminal is larger than a third threshold value; wherein the first threshold is 1 Ω, the second threshold is 2, and the third threshold is 100m Ω, which can also be obtained by manual discrimination.
If both ends of the direct current charging circuit are connected with the single-phase tail pipe through the current limiting device (namely the structure in fig. 4), the total resistance value between the current limiting device and the corresponding grounding terminal is calculated according to the current measured by the current measuring device and the voltage measured by the voltage measuring device, and the resistance value between the tail pipe connected with the current limiting device and the corresponding grounding terminal is calculated according to the total resistance value and the resistance value of the current limiting device.
To further illustrate the above process, the following are exemplified:
s1) selecting A, B two-phase tail tube to connect with dc charging circuit, connecting the first clamp and the second clamp in fig. 4 to two-phase copper bar or tail tube on the protection grounding side of high-voltage cable, connecting the third clamp connected with voltage measuring device to C-phase tail tube, applying dc stabilization current.
S2) calculating the resistance value between the A-phase tail pipe and the A-phase grounding end (namely the tail end of the A-phase copper bar) and the resistance value between the B-phase tail pipe and the B-phase grounding end (namely the tail end of the B-phase copper bar) according to the current measured by the current measuring device and the voltage measured by the voltage measuring device.
The current measuring device measures the current on the whole loop, namely the current flowing through A, B phases is consistent, the single-pole double-throw switch acts to connect the first current limiting device with the voltage measuring device, the resistance measured by the voltage measuring device is equivalent to infinity, and no current flows from the tail pipe of the C phase to the copper of the C phase, so that the voltage measuring device is equivalent to measure the voltage of the first current limiting device plus the voltage from the tail pipe of the A phase to the grounding end of the A phase, the total resistance value from the first current limiting device to the grounding end of the A phase can be obtained by dividing the voltage by the current, and then the known resistance value of the first current limiting device is subtracted, so that the resistance value from the tail pipe of the A phase to the grounding end of the A phase can be.
In the same way, the single-pole double-throw switch is operated to connect the second current limiting device with the voltage measuring device, so that the resistance value from the tail pipe of the B phase to the grounding end of the B phase can be obtained.
If no current limiting device is provided, the voltage is divided by the current to directly obtain the resistance value from the tail pipe to the corresponding ground terminal.
S3) adjusting the two tail pipes connected with the dc charging circuit, so that the tail pipe connected this time is different from the gold tail pipe connected for the first time, either A, C two tail pipes are connected with the dc charging circuit, or B, C two tail pipes are connected with the dc charging circuit, which can be selected arbitrarily.
S4) calculating the resistance value of the tail pipe of the C phase to the ground terminal of the C phase based on the current measured by the current measuring means and the voltage measured by the voltage measuring means, the calculation principle being in accordance with that in step S2.
S5) in response to the resistance value between any single-phase tail pipe and the corresponding ground terminal being greater than 1 Ω, or the ratio of the resistance values between any two-phase tail pipe and the corresponding ground terminal being greater than 2 and the maximum resistance value between the single-phase tail pipe and the corresponding ground terminal being greater than 100m Ω, determining a ground connection defect of the high-voltage cable.
The utility model discloses the application direct current source charges (pours into direct current into promptly) the cable tail pipe, and twice charges can be according to current measuring device measuring electric current and voltage measuring device measuring voltage to obtain every looks tail pipe to the resistance between corresponding earthing terminal, judge out the cable tail pipe according to the resistance and to correspond whether defect between the earthing terminal, reduced the number of times of charging, shortened test time, improved efficiency of software testing, high efficiency and nimble have good application prospect.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be considered as the protection scope of the present invention.
Claims (7)
1. The utility model provides an electrified testing arrangement of high tension cable ground connection defect which characterized in that: the device comprises a direct current charging circuit, a voltage measuring device and a change-over switch;
the direct current charging circuit comprises a direct current source and a current measuring device which are connected in series; two ends of the direct current charging circuit are respectively externally connected with two phase tail pipes at the local end; the current measuring device is used for measuring the current of a tail pipe connected with the direct current charging circuit;
one end of the voltage measuring device is externally connected with the residual phase tail pipe at the local end, and the other end of the voltage measuring device is connected with the direct current charging circuit through the change-over switch; through the switching of the selector switch, the voltage measuring device measures the voltage between each tail pipe connected with the direct current charging circuit and the corresponding grounding terminal.
2. The live-line testing device for the ground connection defect of the high-voltage cable according to claim 1, wherein: both ends of the direct current charging circuit and the voltage measuring device are connected with the tail pipe through the current limiting device.
3. The live-line testing device for the ground connection defect of the high-voltage cable according to claim 2, wherein: the voltage measured by the voltage measuring device is equal to the voltage of the current limiting device plus the voltage between the tail pipe connected with the current limiting device and the corresponding grounding terminal.
4. The live-line testing device for the ground connection defect of the high-voltage cable according to claim 3, wherein: the change-over switch is a single-pole double-throw switch, the moving end of the single-pole double-throw switch is connected with the voltage measuring device, and the two static ends of the single-pole double-throw switch are respectively connected with the two ends of the direct-current charging circuit.
5. The live-line testing device for the ground connection defect of the high-voltage cable as claimed in any one of claims 2 to 4, wherein: the current limiting device is a metal coil or a resistor.
6. The live-line testing device for the ground connection defect of the high-voltage cable according to claim 1, wherein: the direct current source is a storage battery power supply or a constant current source with an output current ripple coefficient not more than 0.1%.
7. The live-line testing device for the ground connection defect of the high-voltage cable according to claim 1, wherein: the accuracy of the current measuring device and the accuracy of the voltage measuring device are not lower than 0.2 level.
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| CN202021760022.5U CN212391567U (en) | 2020-08-21 | 2020-08-21 | Electrified testing arrangement of high tension cable ground connection defect |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113759279A (en) * | 2021-08-27 | 2021-12-07 | 江苏省电力试验研究院有限公司 | Live-line test method and device for ground connection defect of high-voltage cable single-ended grounding system |
| CN115236546A (en) * | 2021-04-23 | 2022-10-25 | 通号工程局集团有限公司 | Method and device for shielding grounding redundancy and detection of railway signal cable |
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2020
- 2020-08-21 CN CN202021760022.5U patent/CN212391567U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115236546A (en) * | 2021-04-23 | 2022-10-25 | 通号工程局集团有限公司 | Method and device for shielding grounding redundancy and detection of railway signal cable |
| CN113759279A (en) * | 2021-08-27 | 2021-12-07 | 江苏省电力试验研究院有限公司 | Live-line test method and device for ground connection defect of high-voltage cable single-ended grounding system |
| CN113759279B (en) * | 2021-08-27 | 2024-05-24 | 江苏省电力试验研究院有限公司 | Live test method and device for ground connection defect of single-end grounding system of high-voltage cable |
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