CN111983522B - Cable detection method - Google Patents
Cable detection method Download PDFInfo
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- CN111983522B CN111983522B CN202010874817.7A CN202010874817A CN111983522B CN 111983522 B CN111983522 B CN 111983522B CN 202010874817 A CN202010874817 A CN 202010874817A CN 111983522 B CN111983522 B CN 111983522B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/58—Testing of lines, cables or conductors
- G01R31/60—Identification of wires in a multicore cable
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/025—Measuring very high resistances, e.g. isolation resistances, i.e. megohm-meters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/18—Indicating phase sequence; Indicating synchronism
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
- G01R31/1263—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
- G01R31/1272—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation of cable, line or wire insulation, e.g. using partial discharge measurements
Abstract
The embodiment of the application provides a cable detection method, which comprises three stages: the first stage, the second stage and the third stage. The first stage is as follows: performing a cable validation, comprising: and determining the current cable to be detected from at least one cable to be detected. And a second stage: and performing three-phase sequence checking and insulation resistance detection on the current cable to be detected, wherein after the current cable is subjected to the phase sequence checking and the insulation resistance detection, cable confirmation is performed on the next cable to be detected in the at least one cable to be detected, so that a new cable is determined from the at least one cable to be detected as the current cable to be detected, and then three-phase sequence checking and insulation resistance detection are performed based on the new cable. After all the cables in the at least one cable to be tested are subjected to three-phase sequence checking and insulation resistance detection, entering a third stage: and carrying out voltage withstanding test on all cables in the at least one cable to be tested. Therefore, the cable detection can be completed quickly and simply.
Description
Technical Field
The application relates to the technical field of power cables, in particular to a cable detection method.
Background
The power cable is used for transmitting and distributing electric energy. The power cable is commonly used for urban underground power grids, power station leading-out lines, power supply inside industrial and mining enterprises and underwater power transmission lines crossing the river and the sea. The basic structure of the power cable comprises a wire core, an insulating layer, a shielding layer and a protective layer.
When a cable head of a power cable in operation has a fault, when a new cable and an old cable are butted, or when a power cable is newly installed, cable terminal heads or cable intermediate heads need to be manufactured for the cable again. After the cable terminal and the cable middle head are manufactured, the cable needs to be detected before the cable is formally connected to a power grid.
Because most areas of the cable which is actually put into use are invisible to human eyes, and the laying areas of some cables are several kilometers long, when the cable is detected after the laying of the cable is finished, the detection difficulty is far higher than that before the laying. At present, the whole detection process is complicated and the detection efficiency is low for the cable which is laid.
Disclosure of Invention
The application aims to provide a cable detection method which can solve the problem that the existing power cable detection process is complex.
In a first aspect, an embodiment of the present application provides a cable detection method, where the method includes:
shorting, at a first side, three phases of a target cable of at least one cable under test to ground, the target cable being any one of the at least one cable under test;
detecting each cable of the at least one cable to be tested phase by phase on a second side, wherein an area between the first side and the second side is an invisible shielding area;
if the second side detects that the three-phase insulation resistance of only one cable in the at least one cable to be detected is zero, determining that the currently detected cable with the zero three-phase insulation resistance and the target cable are the same cable as the cable to be detected;
any one of the three phases of the cable to be detected which is short-circuited at the first side,
and the cable to be detected is detected phase by phase on the second side;
if the second side detects that the insulation resistance of only one phase of the cable to be detected is not zero, determining a corresponding core wire with the insulation resistance not being zero as a target phase sequence, marking the phase sequence of the cable to be detected on the first side and the second side, and taking the current non-zero insulation resistance value as the ground insulation resistance value and the interphase insulation resistance value of the target phase sequence;
and short-circuiting the core wires which are subjected to the phase sequence marking and the insulation resistance detection to the ground again on the first side, performing single-phase short-circuit removal on other unmarked phase core wires in the cable to be detected, and performing phase-by-phase detection on the cable to be detected again on the second side until determining the phase sequence, the ground insulation resistance value and the interphase insulation resistance value of all the core wires of the cable to be detected.
By the method, the cable confirmation, the phase sequence check and the insulation resistance detection can be rapidly carried out on a single or a plurality of power cables. The three-phase short circuit is conducted on one side of the cable, the ground is connected to the three-phase short circuit, insulation resistance detection is conducted on the other side of the cable, the current cable to be detected is rapidly determined from at least one cable to be detected according to the three-phase insulation resistance, and the short circuit caused by the cable detection error in power transmission can be avoided. In the method, the phase sequence checking process is carried out when the cable to be detected is confirmed, the insulation resistance detection is completed while the phase sequence checking is carried out, the insulation resistance of single phase to ground and the interphase insulation resistance are simultaneously measured by the thought of measuring one phase in two phases, the switching time of measuring the interphase insulation resistance after the phase to ground insulation resistance is measured is saved, and the short-circuit operation is not required to be carried out on the first side and the second side of the cable. When the method is applied to a scene that a plurality of three-phase cables are mixed together, the cable detection process is simple, phase sequence identification and insulation resistance measurement can be completed quickly, and the detection efficiency is high.
In an alternative embodiment, the method further comprises:
after determining the phase sequence, the earth insulation resistance value and the interphase insulation resistance value of all core wires of the cable to be detected, removing short circuit of all three phases of the target cable;
and taking the next cable in the at least one cable to be detected as a new target cable, and repeatedly executing the steps from the step of short-circuiting the three phases of the target cable in the at least one cable to be detected to the ground at the first side to the step of determining the phase sequence, the ground insulation resistance value and the interphase insulation resistance value of all core wires of the cable to be detected until the phase sequence, the ground insulation resistance value and the interphase insulation resistance value of all the core wires of the cable to be detected are determined.
Through the implementation mode, the detection process of the plurality of cables can be completed quickly.
In an optional embodiment, after determining the phase sequence, the ground insulation resistance value, and the phase-to-phase insulation resistance value of each core wire of all cables in the at least one cable to be tested, the method further includes:
and carrying out voltage withstanding test on all cables in the at least one cable to be tested.
Through the implementation mode, the voltage resistance of the cables can be rapidly detected based on the phase sequence checking and the detection result of the insulation resistance detection.
In an optional embodiment, the performing a voltage withstanding test on all cables in the at least one cable to be tested includes:
and taking all core wires marked as the same phase sequence in the at least one cable to be tested as voltage-withstanding test objects, short-circuiting the core wires of the phase sequences except the voltage-withstanding test objects in the at least one cable to be tested to the ground, mutually connecting the core wires of the voltage-withstanding test objects with the same phase sequence in the at least one cable to be tested in series, and carrying out voltage-withstanding test on the serially connected core wires.
Through the implementation mode, the implementation mode that the withstand voltage test can be rapidly carried out on the multiple cables is provided, and compared with the mode that the withstand voltage test of a single cable is carried out at each time, the processing efficiency is high.
In an optional embodiment, the step of using all core wires marked as the same phase sequence in the at least one cable to be tested as voltage withstand test objects, short-circuiting core wires of other phase sequences except for the voltage withstand test object in the at least one cable to be tested to the ground, connecting the core wires of the voltage withstand test objects with the same phase sequence in the at least one cable to be tested in series, and performing a voltage withstand test on the serially connected core wires includes:
when the core wire marked as the first phase sequence in the at least one cable to be tested is taken as a withstand voltage test object, short-circuiting the core wires marked as the second phase sequence and the third phase sequence in each cable to be tested to the ground at the first side, mutually connecting all the core wires marked as the first phase sequence in series, and carrying out withstand voltage test on the serially connected core wires;
when the core wires marked as the second phase sequence in the at least one cable to be tested are used as a voltage withstanding test object, short-circuiting the core wires marked as the first phase sequence and the third phase sequence in each cable to be tested to the ground at the first side, connecting all the core wires marked as the second phase sequence in series, and carrying out voltage withstanding test on the serially connected core wires;
when the core wire marked as the third phase sequence in the at least one cable to be tested is used as a voltage withstand test object, the core wires marked as the first phase sequence and the second phase sequence in each cable to be tested are short-circuited to the ground at the first side, all the core wires marked as the third phase sequence are connected in series, and the voltage withstand test is performed on the core wires after series connection.
Through the implementation mode, the implementation mode that the voltage withstanding test can be rapidly carried out on the three phases of the plurality of cables is provided.
In an alternative embodiment, the shorting the three phases of the target cable of the at least one cable under test to ground on the first side includes:
three phases of the target cable are shorted to ground at the first side by a shorting stub.
In an optional embodiment, the performing, on the second side, phase-by-phase detection on each cable of the at least one cable under test includes:
and carrying out phase-by-phase detection on each cable in the at least one cable to be detected through a megameter with a specified range.
In an alternative embodiment, the first side and the second side are located at an incoming cabinet and an outgoing cabinet of a cable, respectively, and the target cable is laid in a cable trench or arranged on a cable tray.
In an alternative embodiment, during the phase-by-phase detection of the cable to be detected on the second side, two phases of the cable to be detected are kept grounded.
In an alternative embodiment, the cable to be detected is a three-core cable, and the shielding layer of the cable to be detected is grounded.
Drawings
To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.
Fig. 1 is a flowchart of a cable detection method according to an embodiment of the present application.
Fig. 2 is a schematic view of a cable detection scenario provided in an embodiment of the present application.
Fig. 3 is a schematic diagram of a cable verification principle provided in an embodiment of the present application.
Fig. 4 is a schematic diagram of a phase a detection principle of a cable according to an embodiment of the present application.
Fig. 5 is a schematic diagram illustrating a B-phase detection principle of a cable according to an embodiment of the present application.
Fig. 6 is a schematic diagram illustrating a C-phase detection principle of a cable according to an embodiment of the present application.
Fig. 7 is a schematic diagram of a principle of detecting an a-phase withstand voltage in an example provided in the embodiment of the present application.
Fig. 8 is a schematic diagram of a B-phase withstand voltage detection principle in an example provided in the embodiment of the present application.
Fig. 9 is a schematic diagram of a principle of detecting a C-phase withstand voltage in an example provided in the embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.
Before the power cable is formally connected to a power grid, detection contents such as cable confirmation, phase sequence check, insulation defect detection and the like need to be carried out on the cable. Usually, the insulation defect is detected by testing the insulation resistance of the cable core to the shielding layer and the insulation resistance between the cable core and the cable core, so as to detect whether the cable has the insulation defect. The common detection idea is to separately detect the phase sequence discrimination process and the insulation defect detection process of the cable.
The existing detection idea is as follows: when the phase sequence of the cable is judged, one end of a three-phase cable is grounded, the insulation resistance of the three phases of the cable is measured at the other end of the cable, if the insulation resistance of one phase in the three-phase insulation resistance is remotely detected to be zero, the core wire with the zero insulation resistance of the phase and the grounded core wire are considered to be the core wire of the same phase sequence of the same cable, and then the core wires are marked to be the same phase sequence at the two ends of the cable, for example, marked to be A phase. Based on the principle, the other two core wires in the cable are respectively subjected to phase sequence checking and marking. The phase sequence checking process for completing one three-phase cable requires 9 tests.
After the phase sequence checking process of a three-phase cable is completed, three phase-to-ground insulation resistance and phase-to-phase insulation resistance of the cable are detected respectively, and the insulation defect detection process needs 6 times of testing. If the phase sequence checking process and the insulation resistance detecting process of one three-core cable need 15 times of tests according to the detecting mode, the testing process is complex, the testing times are many, and certain electric shock danger exists. And moreover, due to the complex test process, the phase sequence marking error is caused by the easy negligence of workers, so that the test labor intensity of the workers is increased, and the detection efficiency is reduced. These factors will be unfavorable for the cable to put into the electric wire netting fast and use, can influence the recovery time of producing the power consumption of life, will produce adverse effect to the production. The process of completing the insulation resistance detection in the embodiment of the application includes: and determining the insulation resistance value to the ground and the insulation resistance value between phases.
Moreover, if there are a plurality of power cables to be subjected to inspection, or a power cable to be checked is mixed in a plurality of power cables, the cable inspection complexity increases.
In view of the above, the inventors propose the following embodiments to improve that the cable detection method provided by the embodiments of the present application can quickly detect a plurality of power cables.
The cable detection principle provided by the embodiment of the application comprises a first stage, a second stage and a third stage.
The first stage is as follows: cable validation, comprising: and determining the current cable to be detected from at least one cable to be detected.
Wherein the second stage is entered after the current cable to be tested is determined.
And a second stage: phase sequence checking and insulation resistance detection, comprising: and carrying out phase sequence checking and insulation resistance detection on the three phases of the current cable to be detected.
After the three phases of the current cable to be detected are subjected to phase sequence checking and insulation resistance detection, cable confirmation is carried out on the next cable in the at least one cable to be detected, so that a new cable is determined from the at least one cable to be detected to serve as the current cable to be detected, and then three-phase sequence checking and insulation resistance detection are carried out on the basis of the new cable.
And after all the cables in the at least one cable to be tested are subjected to three-phase sequence checking and insulation resistance detection, entering a third stage.
And a third stage: and carrying out voltage withstanding test on all cables in the at least one cable to be tested.
The cable confirmation of a plurality of cables can be rapidly completed through the first stage, and the phase sequence check and the insulation resistance detection can be simultaneously carried out on a single cable through the second stage. And the third stage can be used for rapidly detecting the voltage resistance of the plurality of cables.
The following describes a cable detection method provided in an embodiment of the present application in detail.
Referring to fig. 1, fig. 1 is a flowchart of a cable detection method according to an embodiment of the present disclosure. The detection object in the embodiment of the present application is a three-phase cable.
As shown in fig. 1, the method includes: steps S11-S16. Wherein S11-S13 belong to the first stage described above. S14-S16 belong to the second stage described above.
S11: three phases of a target cable of at least one cable under test are shorted to ground on a first side, the target cable being any one of the at least one cable under test.
In an embodiment of the present application, the shielding layer of each of the at least one cable under test is grounded. The target cable is a three-core cable. Wherein three phases of the target cable may be shorted to ground at the first side by a shorting line. This implementation is simpler.
S12: and carrying out phase-by-phase detection on each cable of the at least one cable to be detected on a second side, wherein the area between the first side and the second side is an invisible shielding area.
In an application scenario, the first side and the second side are respectively located at an incoming line cabinet and an outgoing line cabinet of the cable. The target cable may be a cable laid in a cable trench or provided on a cable tray.
S13: and if the three-phase insulation resistance of only one cable of the at least one cable to be detected is detected to be zero at the second side, determining that the currently detected cable with the zero three-phase insulation resistance and the target cable are the same cable as the cable to be detected.
In an application scenario, as shown in fig. 2, three-phase cables (referred to as cables for short) are laid between two high-voltage power cabinets P1 and P2, two of the three-phase cables are used for connecting other power cabinets, and one cable is used for connecting electric devices such as transformers and motors. The dashed area between P1 and P2 is the portion of each cable that is hidden. If the cables are not checked and confirmed, the cable detection result cannot be guaranteed. The three-phase cables can be used as cables to be tested. Each origin in fig. 2 represents a core within a cable.
When a cable K at P2 needs to be detected (the cable is a three-phase cable that has been determined to be connected to P1), one end of the cable K near P2 may be used as a first side, and one end of the cable K near P1 may be used as a second side. Based on S11 described above, the cable K is a target cable, and as shown in fig. 3, one end of the cable K is short-circuited to the ground for three phases, and phase-by-phase detection is performed at the other end of the cable K. For example, three phases of the cable K may be shorted to ground at P2. The "PBC" in fig. 3 denotes the shielding layer of the cable.
Wherein the three phases of the cable can be short-circuited to ground by a short-circuit with a plurality of clamps. In one example, the shorting stub includes four clips, three of which are used to connect three phase conductors of a single cable, and the last of which is used to ground.
When the three phases at one end of the cable K are shorted to the ground, based on the above S12, phase-by-phase detection can be performed on the three cables including the cable K at P1 through the megohmmeter, and three sets of three-phase insulation resistances corresponding to the three cables are obtained.
Optionally, each cable of the at least one cable to be tested may be detected phase by a specified-range megohmmeter or a high-range multimeter. In one example, the megohmmeter used to perform the phase-by-phase testing to derive the insulation resistance is a high voltage megohmmeter in excess of 2500V.
If the three-phase insulation resistance of two cables in the three cables is detected to be not zero and the three-phase insulation resistance of one cable is detected to be zero, the cable with the three-phase insulation resistance of zero is considered to be the cable K (the current target cable) and serves as the current cable to be detected. At this time, a cable marking may be performed, for example, the cable K may be marked as cable No. 1 at both ends (P1, P2) of the cable K. Then, phase sequence checking and insulation resistance value detection are carried out on the No. 1 cable. Based on the principle, the cables can be checked and confirmed respectively for the cables, so that the second cable and the third cable in the cables to be detected are found out, and phase sequence checking and insulation resistance value detection are carried out on the second cable and the third cable respectively. Therefore, the problem that the cable detection result is not matched with the actually tested cable can be avoided.
S14: and removing the short circuit of any one of the three phases of the cable to be detected which is short-circuited at the first side, and carrying out phase-by-phase detection on the cable to be detected at the second side.
And in the process of phase-by-phase detection of the cable to be detected on the second side, keeping two phases of the cable to be detected grounded.
S15: if the second side detects that the insulation resistance of only one phase of the cable to be detected is not zero, determining a corresponding core wire with the insulation resistance not being zero as a target phase sequence, marking the phase sequence of the cable to be detected on the first side and the second side, and taking the current non-zero insulation resistance value as the ground insulation resistance value and the interphase insulation resistance value of the target phase sequence.
S16: and short-circuiting the core wires which are subjected to the phase sequence marking and the insulation resistance detection to the ground again on the first side, performing single-phase short-circuit removal on other unmarked phase core wires in the cable to be detected, and performing phase-by-phase detection on the cable to be detected again on the second side until determining the phase sequence, the ground insulation resistance value and the interphase insulation resistance value of all the core wires of the cable to be detected.
For the sake of understanding, the cables K are still used as examples for the above S14 to S16. After the cable confirmation process for the cable K is completed through S11 to S13, the cable K may be regarded as a cable to be detected, and three-phase sequence checking and insulation resistance detection may be performed on the cable K. For convenience of description, three phase sequences to be checked by the cable to be detected are recorded as a first phase sequence, a second phase sequence and a third phase sequence. In one example, the first phase sequence, the second phase sequence, and the third phase sequence may be defined as a phase a, a phase B, and a phase C, respectively.
As shown in fig. 4, when the cable K is determined as the cable to be detected, any one phase of the cable K whose three phases have been short-circuited to the ground may be de-short-circuited. In fig. 4, K1 and K2 denote a first side and a second side, respectively.
As an embodiment, the short-circuited core wire of one phase of the cable K may be separated from the short-circuited wire, so that the core wires of the other two phases of the cable K remain short-circuited to the ground. At this time, since the cable K has already been confirmed, the three-phase insulation resistance of the cable K can be sequentially detected by a megohmmeter of 2500V at the other end (the end that is not subjected to the short-circuit processing, i.e., the second side) of the cable K, so that the current cable to be detected is detected phase by phase to obtain three insulation resistance values. If it is detected that two insulation resistances of three phases of the current cable K to be detected are zero and the insulation resistance of the remaining one phase is not zero, the one phase with the insulation resistance value not zero may be marked as a first phase sequence, for example, the one phase with the insulation resistance value not zero may be defined as an a phase, and an a phase identifier may be added to a core wire with the insulation resistance value not zero in the cable (see fig. 4). The measured stable values of the megohmmeter at this time are the insulation resistance value of the first phase sequence (phase a) to the ground, the phase-to-phase insulation resistance value of the first phase sequence (phase a) to the second phase sequence (phase B), and the phase-to-phase insulation resistance value of the first phase sequence (phase a) to the third phase sequence (phase C). Therefore, the phase sequence checking of the phase A of the cable and the insulation resistance detection can be simultaneously realized.
Based on the principle, phase sequence checking and insulation resistance detection can be carried out on the second phase sequence and the third phase sequence of the current cable to be detected.
After the phase sequence detection and the insulation resistance measurement of the phase a are completed based on the principle of fig. 4, as shown in fig. 5, the phase a core wire that has been subjected to the phase sequence marking and the insulation resistance detection in the cable K may be shorted to the ground again on the first side, and any of the remaining unmarked two-phase core wires (i.e., unmarked other phase core wires) in the cable K may be de-shorted. And then, carrying out phase-by-phase detection on the current cable K to be detected again through a megohmmeter on the second side to obtain three insulation resistance values of the cable K. If it is detected that the insulation resistance of two of the three phases of the cable K is zero and the insulation resistance of the remaining one phase is not zero at this time, the one phase with the non-zero insulation resistance value may be marked as a second phase sequence, for example, the one phase with the non-zero insulation resistance value may be defined as a B phase, and a B phase identifier may be added to the core wire with the non-zero insulation resistance value in the cable (see fig. 5). The measured stable values of the megohmmeter at this time are the insulation resistance value of the second phase sequence (phase B) to the ground, the phase insulation resistance value of the second phase sequence (phase B) to the first phase sequence (phase a), and the phase insulation resistance value of the second phase sequence (phase B) to the third phase sequence (phase C). Therefore, the phase sequence checking of the phase B of the cable and the insulation resistance detection can be simultaneously realized.
Similarly, after the phase sequence checking and the insulation resistance detection are completed on the second phase sequence (phase B) of the cable K, as shown in fig. 6, the phase B core wire which has been subjected to the phase sequence marking and the insulation resistance detection may be shorted to the ground again, and the unmarked last phase core wire in the cable K may be de-shorted, so as to keep the phase a and phase B core wires of the cable K on the first side shorted to the ground. And then, carrying out phase-by-phase detection on the current cable K to be detected again through a megohmmeter on the second side to obtain three insulation resistance values of the cable K. If it is detected that the insulation resistance of two of the three phases of the cable K is zero and the insulation resistance of the remaining one phase is not zero, the phase with the non-zero insulation resistance value may be marked as a third phase sequence, for example, the phase with the non-zero insulation resistance value may be defined as a C-phase, and a C-phase identifier may be added to the core wire with the non-zero insulation resistance value in the cable (see fig. 6). The measured stable value of the megohmmeter at this time is taken as an insulation resistance value of the third phase sequence (C phase) with respect to the ground, an inter-phase insulation resistance value of the third phase sequence (C phase) with respect to the first phase sequence (a phase), and an inter-phase insulation resistance value of the third phase sequence (C phase) with respect to the second phase sequence (B phase). Therefore, the checking of the C phase sequence of the cable and the detection of the insulation resistance can be simultaneously realized.
Through the methods of S11-S16, cable confirmation, phase sequence check and insulation resistance detection can be rapidly carried out on a plurality of power cables. The three-phase short circuit is conducted on one side of the cable, the insulation resistance detection is conducted on the other side of the cable, the current cable to be detected is determined from one or more cables to be detected quickly according to the three-phase insulation resistance, and the short circuit caused by the cable detection error in the power transmission process can be avoided. In the method, the phase sequence checking process is carried out when the cable to be detected is confirmed, the insulation resistance detection is completed while the phase sequence checking is carried out, the insulation resistance of single phase to ground and the interphase insulation resistance are simultaneously measured by the thought of measuring one phase in two phases, the switching time of measuring the interphase insulation resistance after the phase to ground insulation resistance is measured is saved, and the short-circuit operation is not required to be carried out on the first side and the second side of the cable. When the method is applied to a scene that a plurality of three-phase cables are mixed together, the cable detection process is simple, phase sequence identification and insulation resistance measurement can be completed quickly, and the detection efficiency is high.
In the method, the phase sequence check can be completed while the single-phase insulation resistance at two ends of the cable is measured, the number of times of three-phase detection on the single cable can be reduced from 15 to 9, the number of times of repeated detection on the insulation resistance can be reduced, the working efficiency is improved, the cable detection efficiency can be improved in a multi-cable detection scene, the rapid power supply recovery is facilitated, the implementation process of the whole method is simple, the implementation is easy, and the phase sequence check and the detection accuracy of the insulation resistance can be improved.
Optionally, the cable detection method may further include steps S17 to S18. S17-S18 may be applicable to detection scenarios where multiple cables are present.
S17: and after determining the phase sequence, the earth insulation resistance value and the interphase insulation resistance value of all core wires of the cable to be detected, removing short circuit of all three phases of the target cable.
S18: and taking the next cable in the at least one cable to be tested as a new target cable, and repeatedly executing the steps S11-S16 until the phase sequence, the ground insulation resistance value and the interphase insulation resistance value of all core wires of all cables in the at least one cable to be tested are determined.
For easy understanding, when the three cables at P1 in fig. 2 are used as the cables to be detected, if the current cable K to be detected among the three cables has been detected by the method of S11 to S16, after all the cores (three-phase cores) of the cable K complete the phase sequence marking and the insulation resistance detection, all the three phases of the cable K can be disconnected. Then, any one cable M from the other two cables except the cable K in the three cables at P1 can be used as a new target cable, and then the method of S11-S16 is executed again based on the new cable M, so as to quickly perform phase sequence check marking and insulation resistance detection on the cable M.
According to the method of S11-S16, the cable to be detected, which is required to be subjected to cable detection, can be quickly found out from at least one cable to be detected, and the phase sequence check mark and the insulation resistance detection can be quickly carried out on the found single cable to be detected at the same time. Based on the principle of the method of S11-S16, if there are other cables to be detected in at least one cable to be detected, the method of S17-S18 may be executed, so as to perform cable detection on the other cables not detected in at least one cable to be detected according to the principle of the method of S11-S16, respectively. Therefore, the detection process of a plurality of cables can be completed quickly.
Optionally, after the phase sequence marking and the insulation resistance detection are completed on all the cables in the at least one cable to be tested, the cable detection method may further include step S19 (i.e., the third stage described above).
S19: and carrying out voltage withstanding test on all cables in the at least one cable to be tested.
Therefore, the voltage resistance of the plurality of cables can be rapidly detected based on the phase sequence check and the detection result of the insulation resistance detection.
As an implementation manner of the above S19, S19 may include: and taking all the core wires marked with the same phase sequence in the at least one cable to be tested as voltage-withstanding test objects, short-circuiting the core wires of other phase sequences except the voltage-withstanding test objects in the at least one cable to be tested to the ground, mutually connecting the core wires of the voltage-withstanding test objects with the same phase sequence in the at least one cable to be tested in series, and carrying out voltage-withstanding test on the serially connected core wires.
Therefore, the implementation mode that the voltage withstanding test can be rapidly carried out on a plurality of cables is provided, and compared with the mode that the voltage withstanding test of a single cable is carried out at each time, the processing efficiency is higher. The specific voltage value, the voltage increment and the voltage application time applied in the withstand voltage test process can be determined according to the attributes of the cable, and the specific pressure parameters in the withstand voltage test process are not limited.
Optionally, the implementation process of performing the voltage withstanding test on the serially connected core wires by taking all the core wires marked as the same phase sequence in the at least one cable to be tested as the voltage withstanding test object, short-circuiting the core wires of the phase sequences of the at least one cable to be tested except the voltage withstanding test object to the ground, and serially connecting the core wires of the voltage withstanding test objects with the same phase sequence in the at least one cable to be tested, may include the substeps of: S191-S193.
S191: when the core wire marked as the first phase sequence in the at least one cable to be tested is used as a withstand voltage test object, the core wires marked as the second phase sequence and the third phase sequence in each cable to be tested are short-circuited to the ground at the first side, all the core wires marked as the first phase sequence are mutually connected in series, and the withstand voltage test is carried out on the core wires after series connection.
Taking three cables to be tested as an example, after the three cables to be tested are checked by phase sequence and the ground insulation resistance and the phase-to-phase insulation resistance of each cable are measured, as shown in fig. 7, a voltage withstanding test can be performed on the core wires marked as the first phase sequence (phase a) in the three cables to be tested. When the voltage withstand test of the first phase sequence (A phase) is carried out on the three cables to be tested, core wires of the second phase sequence (B phase) and the third phase sequence (C phase) on one side of each cable in the three cables to be tested are connected to the ground in a short-circuit mode. And then all core wires marked as the first phase sequence (A phase) in the three cables to be tested are connected in series end to obtain a series connection chain formed by the first phase sequence (A phase) core wires of each cable. At this time, the core wires (serial links) after serial connection can be subjected to a withstand voltage test by a dc withstand voltage tester. The position pointed by the arrow in fig. 7 can be used as the pressurizing end of the first phase sequence (phase a) withstand voltage test.
The voltage can be applied to the head end of the series link through the direct current withstand voltage tester, and the leakage current of the series link is detected. Within a period of time in the voltage application process, whether the leakage current of the serial link is stabilized within a range is detected by the direct-current voltage-withstanding tester, so that whether the voltage-withstanding performance of the first phase sequence (phase A) of the three cables to be tested really meets the designed voltage-withstanding index is judged. If the serial link formed by the first phase sequence core wires of the cables meets the condition of stable leakage current in the process of the withstand voltage test, the first phase sequence (phase A) of the three cables to be tested can be regarded as passing the withstand voltage test. Compared with a mode of respectively applying voltages to three core wires marked as a first phase sequence (A phase) in three cables to be tested, the method can reduce the test times and can quickly finish the voltage withstanding test in a multi-cable test scene.
S192: when the core wires marked as the second phase sequence in the at least one cable to be tested are used as a withstand voltage test object, the core wires marked as the first phase sequence and the third phase sequence in each cable to be tested are short-circuited to the ground at the first side, all the core wires marked as the second phase sequence are connected in series, and the withstand voltage test is carried out on the serially connected core wires.
Similar to the implementation principle of S191, taking three cables to be tested as an example, after all the three cables to be tested are checked by the phase sequence and the ground insulation resistance and the phase-to-phase insulation resistance of each cable are measured, as shown in fig. 8, the core wires marked as the second phase sequence (phase B) in the three cables to be tested may be subjected to a voltage withstanding test. When the two cables to be tested are subjected to a second phase sequence (phase B) withstand voltage test, core wires of a first phase sequence (phase A) and a third phase sequence (phase C) on one side of each of the three cables to be tested are connected to the ground in a short-circuit mode. And then all the core wires marked as a second phase sequence (B phase) in the three cables to be tested are connected in series end to obtain a series link formed by the second phase sequence (B phase) core wires of each cable. At this time, the core wires (serial links) after serial connection can be subjected to a withstand voltage test by a direct current withstand voltage tester. The arrow in fig. 8 indicates the position as the pressurizing end of the second phase sequence (B phase) withstand voltage test.
And in a period of time in the voltage application process, detecting whether the leakage current of the serial link is stabilized in a range by the direct-current voltage-resistant tester, so as to judge whether the second phase sequence (B phase) of the three cables to be tested really meets the designed voltage-resistant index on the voltage-resistant performance. If the serial link formed by the second phase sequence (B phase) core wires of the cables meets the condition of stable leakage current in the process of the withstand voltage test, the second phase sequence (B phase) of the three cables to be tested can be regarded as passing the withstand voltage test. Compared with a mode of respectively applying voltages to three core wires marked as a second phase sequence (B phase) in three cables to be tested, the method can reduce the test times and can quickly finish the voltage withstanding test in a multi-cable test scene.
S193: when the core wire marked as the third phase sequence in the at least one cable to be tested is used as a voltage withstand test object, the core wires marked as the first phase sequence and the second phase sequence in each cable to be tested are short-circuited to the ground at the first side, all the core wires marked as the third phase sequence are connected in series, and the voltage withstand test is performed on the core wires after series connection.
Similar to the implementation principle of S191 and S192, taking three cables to be tested as an example, after all the three cables to be tested are checked by the phase sequence and the ground insulation resistance and the phase insulation resistance of each cable are measured, as shown in fig. 9, the core wires marked as the third phase sequence (phase C) in the three cables to be tested may be subjected to a voltage withstanding test. When the three cables to be tested are subjected to a third phase sequence (C phase) withstand voltage test, the core wires of the first phase sequence (A phase) and the second phase sequence (B phase) on one side of each cable in the three cables to be tested are firstly short-circuited to the ground. And then all the core wires marked as a third phase sequence (C phase) in the three cables to be tested are connected in series end to obtain a series link formed by the third phase sequence (C phase) core wires of each cable. At this time, the core wires (serial links) after serial connection can be subjected to a withstand voltage test by a direct current withstand voltage tester. The position pointed by the arrow in fig. 9 can be used as the pressurizing end of the third phase sequence (C-phase) voltage withstand test.
And in a period of time in the voltage application process, detecting whether the leakage current of the serial link is stabilized in a range by the direct-current withstand voltage tester, so as to judge whether the third phase sequence (C phase) of the three cables to be tested really meets the designed withstand voltage index on the withstand voltage performance. If the serial link formed by the third phase sequence (C phase) core wires of the cables is detected to meet the condition of stable leakage current in the process of the voltage withstanding test, the third phase sequence (C phase) of the three cables to be tested can be regarded as passing the voltage withstanding test. Compared with a mode of respectively applying voltages to three core wires marked as a third phase sequence (C phase) in three cables to be tested, the test frequency can be reduced, and the voltage withstanding test can be quickly completed in a multi-cable test scene.
Through the implementation mode of S191-S193, for a plurality of cables to be tested, the withstand voltage test of the plurality of cables can be realized only by carrying out withstand voltage test on three serial links, and compared with the mode of independently carrying out withstand voltage test on each cable in the plurality of cables to be tested, the cable detection efficiency can be improved, and the three-phase withstand voltage test of the plurality of cables can be quickly completed.
To sum up, the cable detection method provided by the embodiment of the application can be applied to the test of three-phase cables, and in the cable detection process, the three-phase sequence of each cable can be confirmed without knowing the phase sequences at two sides of the cable, and the phase sequence can be defined by self after the phase sequence check is completed. The current cable to be detected is confirmed from one or more cables to be detected before phase sequence checking and insulation detection are carried out, so that phase sequence checking and insulation resistance detection are carried out on a single cable to be detected at the same time according to the confirmed single cable to be detected, and detection accuracy and detection efficiency can be considered at the same time. When a single cable is detected, phase sequence checking and insulation resistance detection can be simultaneously completed by short-circuiting two phases of the cable on one side and measuring insulation resistance on the other side of the cable, and short-circuiting operation does not need to be simultaneously performed on two sides of the cable. When the phase sequence checking is carried out on the single cable by the method, the insulation resistance of the single phase to the ground and the phase insulation resistance can be measured simultaneously, and the time for measuring the phase insulation resistance after the insulation resistance of the single phase to the ground is measured respectively can be saved. The cable detection method is not only suitable for detection and confirmation of a single cable, but also suitable for detection of a plurality of three-phase cables, can be used for quickly completing cable confirmation, phase sequence checking, insulation resistance measurement and voltage resistance test of the plurality of cables, is simple in overall measurement process, is less in measurement times, and is beneficial to quickly recovering power consumption.
In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.
The above embodiments are merely examples of the present application and are not intended to limit the scope of the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (8)
1. A method of cable testing, the method comprising:
shorting three phases of a target cable of at least one cable to be tested to the ground on a first side, wherein the target cable is any one power cable of the at least one cable to be tested;
detecting each cable of the at least one cable to be tested phase by phase on a second side, wherein an area between the first side and the second side is an invisible shielding area;
if the second side detects that the three-phase insulation resistance of only one cable in the at least one cable to be detected is zero, determining that the currently detected cable with the zero three-phase insulation resistance and the target cable are the same cable as the cable to be detected;
removing the short circuit of any one of the three phases of the cable to be detected which is short-circuited at the first side, and carrying out phase-by-phase detection on the cable to be detected at the second side;
if the second side detects that the insulation resistance of only one phase of the cable to be detected is not zero, determining a corresponding core wire with the insulation resistance not being zero as a target phase sequence, marking the phase sequence of the cable to be detected on the first side and the second side, and taking the current non-zero insulation resistance value as the ground insulation resistance value and the interphase insulation resistance value of the target phase sequence;
short-circuiting the core wires which are subjected to the phase sequence marking and the insulation resistance detection to the ground again on the first side, removing short-circuiting of other phase core wires which are not marked in the cable to be detected in a single phase mode, and detecting the cable to be detected in a phase-by-phase mode again on the second side until the phase sequence, the ground insulation resistance value and the interphase insulation resistance value of all the core wires of the cable to be detected are determined;
and taking all the core wires marked with the same phase sequence in the at least one cable to be tested as voltage-withstanding test objects, short-circuiting the core wires of other phase sequences except the voltage-withstanding test objects in the at least one cable to be tested to the ground, mutually connecting the core wires of the voltage-withstanding test objects with the same phase sequence in the at least one cable to be tested in series, and carrying out voltage-withstanding test on the serially connected core wires.
2. The method of claim 1, further comprising:
after determining the phase sequence, the earth insulation resistance value and the interphase insulation resistance value of all core wires of the cable to be detected, removing short circuit of all three phases of the target cable;
and taking the next cable in the at least one cable to be detected as a new target cable, and repeatedly executing the steps from the step of short-circuiting the three phases of the target cable in the at least one cable to be detected to the ground at the first side to the step of determining the phase sequence, the ground insulation resistance value and the interphase insulation resistance value of all core wires of the cable to be detected until the phase sequence, the ground insulation resistance value and the interphase insulation resistance value of all the core wires of the cable to be detected are determined.
3. The method according to claim 1, wherein the step of using all the cores marked with the same phase sequence in the at least one cable to be tested as a voltage resistance test object, the step of short-circuiting the cores of the other phase sequences except the voltage resistance test object in the at least one cable to be tested to the ground, and the step of serially connecting the cores of the voltage resistance test objects with the same phase sequence in the at least one cable to be tested to each other, and the step of performing the voltage resistance test on the serially connected cores comprises the steps of:
when the core wire marked as the first phase sequence in the at least one cable to be tested is used as a voltage withstanding test object, short-circuiting the core wires marked as the second phase sequence and the third phase sequence in each cable to be tested to the ground at the first side, connecting all the core wires marked as the first phase sequence in series, and carrying out voltage withstanding test on the core wires after series connection;
when the core wires marked as the second phase sequence in the at least one cable to be tested are used as a voltage withstanding test object, short-circuiting the core wires marked as the first phase sequence and the third phase sequence in each cable to be tested to the ground at the first side, connecting all the core wires marked as the second phase sequence in series, and carrying out voltage withstanding test on the serially connected core wires;
when the core wire marked as the third phase sequence in the at least one cable to be tested is used as a voltage withstand test object, the core wires marked as the first phase sequence and the second phase sequence in each cable to be tested are short-circuited to the ground at the first side, all the core wires marked as the third phase sequence are connected in series, and the voltage withstand test is performed on the core wires after series connection.
4. The method of claim 1, wherein shorting three phases of a target cable of the at least one cable under test to ground on the first side comprises:
three phases of the target cable are shorted to ground at the first side by a shorting stub.
5. The method of claim 1, wherein the phase-by-phase testing each of the at least one cable under test on the second side comprises:
and carrying out phase-by-phase detection on each cable in the at least one cable to be detected through a megameter with a specified range.
6. The method of claim 1, wherein the first side and the second side are located at an incoming cabinet and an outgoing cabinet of a cable, respectively, and the target cable is laid in a cable trench or on a cable tray.
7. The method according to claim 1, characterized in that during the phase-by-phase testing of the cable to be tested on the second side, the two phases of the cable to be tested are kept grounded.
8. Method according to any one of claims 1 to 7, characterized in that the cable to be tested is a three-core cable, the shielding of which is earthed.
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