Street lamp line fault point quick searching method

Abstract

The invention discloses a street lamp line fault point rapid searching method, which uses an AC constant current power supply to be added to two ends of a fault line, does not need to dismount a street lamp line, uses a common clip-on ammeter to carry out current measurement, can rapidly find out the rear end of a short circuit point at which wiring is located, and can roughly calculate the short circuit point distance by measuring the magnitude of voltage. The short-circuit position can be quickly found without dismounting the street lamp main power line, and the fault processing time is shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of street lamp in electrical engineering, and particularly relates to a method for quickly locating a fault point of a street lamp line. Background Art

[0002] The street lamp line usually leads out from a main line, and each street lamp takes power in parallel from the main line. Since the main line needs to pass through each street lamp, it is equivalent to each street lamp taking power in parallel from the adjacent street lamp. When the street lamp line has a phase-to-phase or phase-to-ground short circuit, since the street lamp is still connected in parallel in the circuit, when using an insulation resistance tester or the ohm range of a multimeter to measure the resistance difference between the normal phase and the faulty phase is very small and cannot be distinguished. The existing method is to untie the wiring of each street lamp one by one, try to send power to check whether there is a trip, and gradually search until the specific grounding point can be determined. When the street lamp line is long (several kilometers), there are many street lamps (20 - 30 lamps), and the line is relatively complex (tree structure), it takes a lot of time to determine the fault point, and at the same time, it takes a lot of time to reconnect the line.

[0003] Currently, there have been relevant researches on locating the fault point of the street lamp line. For example, CN201811015251.1 discloses a method for safely and quickly locating the fault of the street lamp line, including the following steps: selecting the size of the series-connected capacitor according to the power supply radius of the faulty cable of the street lamp branch and the nature of the lamp; respectively connecting suitable-capacity capacitors in series in the A, B, and C phase outgoing cables and measuring the zero-sequence current of the outgoing faulty cable in the power distribution cabinet. If it is found that the zero-sequence current exists in all of them, it is judged that the grounding fault point is on the N phase, and the voltage is applied between any one of the A, B, and C phases and the N phase; if it is found that the zero-sequence current exists only in any one of the A, B, and C phases, it is judged that the grounding fault point is on this phase, and the voltage is applied between the faulty phase and the N phase. A high-precision clamp ammeter is used to measure the zero-sequence current of the cables A, B, C, and N at the lamp post. According to the mutation point of the zero-sequence current, it can be judged between which two poles or on the lamp post lead-up wire the grounding fault point is. It is a method for relatively safely and quickly locating the grounding fault of the street lamp line and can be used for most lamp posts with normal diameters. This method requires estimating the capacitance of the line and the street lamp, selecting a suitable series-connected capacitor, and at the same time, a high-precision clamp ammeter is needed for current measurement. The operation is relatively complex, and the cost is relatively high. A large number of different models of capacitors need to be prepared, and complex calculations are required before the operation, which cannot be quantified. At the same time, this method uses 220V mains power supply for power-on fault troubleshooting, which is not safe and reliable enough. If the operation is not good, it may cause personal injury accidents. Summary of the Invention

[0004] In view of the problems that when the current street lamp lines are long, there are many street lamps, and the lines are relatively complex, it takes a lot of time to determine the fault point, and a large amount of time is required to reconnect the lines, the present invention provides a method for quickly finding the fault point of street lamp lines. This method applies an AC constant current power supply to both ends of the faulty line. Without removing the street lamp lines, a common clamp ammeter is used for current measurement, and the short - circuit point can be quickly found at the back end of which parallel connection wire. By measuring the magnitude of the voltage, the distance of the short - circuit location can be roughly estimated, so that the short - circuit position can be found quickly without removing the main power supply line of the street lamp, shortening the fault handling time.

[0005] The object of the present invention is achieved through the following technical solutions:

[0006] A method for quickly finding the fault point of street lamp lines, the applicable scope includes but is not limited to single - phase grounding, two - phase short - circuit, three - phase short - circuit street lamp line faults, and is applicable but not limited to the investigation of street lamp line fault points, including the following steps:

[0007] S1: Connect an AC constant current power supply between the main line of phase A of the street lamp and the grounding electrode (grounding wire);

[0008] S2: Gradually increase the output current of the constant current source to 1A - 5A, as long as it can be clearly observed with a clamp meter;

[0009] S3: Use a common clamp meter to measure the current output by the constant current source at the lamp post, and judge the position of the fault point according to the current mutation point.

[0010] Furthermore, the grounding electrode described in S1 is the grounding part of the electrical system, such as grounding wire, grounding pile, etc. The applicable scope of this method includes but is not limited to single - phase grounding, two - phase short - circuit, three - phase short - circuit and other street lamp line faults, and is applicable but not limited to the investigation of street lamp line fault points. The following steps only take the phase A grounding fault (belonging to single - phase grounding) as an example, and workers in this industry can simply apply this step to other faults such as single - phase grounding, two - phase short - circuit, three - phase short - circuit without creative transformation.

[0011] Furthermore, the AC constant current power supply described in S1 only needs an open - circuit output of 24V or less. For safety considerations, it is recommended to use an AC constant current power supply with an open - circuit output of 24V or less. A higher open - circuit output voltage does not affect the practice of this method.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. The method for quickly finding the fault point of street lamp lines according to the present invention improves the efficiency of finding street lamp line faults.

[0014] Calculated based on 30 street lights, using the conventional method, at least 4 people are required for the operation, and it takes 1 to 2 days to troubleshoot and handle the faults. Using this method, 2 people can complete the fault troubleshooting and handling in 1 hour. When the number of street lights is larger and the connection is more complex, the effect will be more obvious.

[0015] 2. For the method for quickly finding the fault point of a street lamp line according to the present invention, there is no need to adjust the operation method according to the lamp type and the power supply range. At the same time, it is also applicable to resistance lamps such as tungsten lamps and incandescent lamps. It has a wide range of uses, a simple operation method, and is easy to promote. When the AC constant current source used in this solution is open circuit, the voltage is the power supply voltage (usually below 24V, and there are components such as transformers between it and the 220V mains power for isolation). All parts that personnel can touch are within the safe voltage, and there is no risk of electric shock. At the same time, this method does not require the use of a high-precision clamp ammeter, and only an ordinary clamp ammeter can be used for operation, which greatly saves costs. For some fault conditions in the prior art, the device will trip, and only the original fault troubleshooting method can be used, and the applicable range is not wide enough. At the same time, this solution has low requirements for the AC constant current source and the clamp ammeter, and there are a large number of cheap and high-quality products available on the market for selection. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the schematic diagram of a method for quickly finding the fault point of a street lamp line according to Embodiment 1 of the present invention;

[0017] Figure 2 is the schematic diagram of a method for quickly finding the fault point of a street lamp line according to Embodiment 2 of the present invention;

[0018] Figure 3 is the schematic diagram of a method for quickly finding the fault point of a street lamp line according to the present invention in actual use.

[0019] Figure 4 is the schematic diagram of the comparative example of the present invention in actual use. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following further describes the specific embodiments of the present invention in conjunction with the embodiments.

[0021] Embodiment 1:

[0022] A method for quickly finding the fault point of a street lamp line includes the following steps:

[0023] According to the circuit principle, when an AC constant current source is added, since the resistance at the fault point is much smaller than the lamp resistance, almost all the current flows to the fault point. Due to the small resistance at the fault point and the power limitation of the constant current source, the voltage generated on the wire is not high, the lamp will not conduct and will not be damaged, and it will not cause harm to personnel;

[0024] S1: Refer to Figure 1 and Figure 3 , taking the AB two-phase short circuit as an example (since the judgment of fault types such as three-phase short circuit, two-phase short circuit, and single-phase grounding is relatively simple, this method will not be elaborated), disconnect the sub-switch of the AB two phases or remove the power supply wires of the AB two phases, and connect the constant current source to the power supply side of the AB two phases;

[0025] S2: Gradually increase the output current of the AC constant current source until it can be clearly observed using a clamp ammeter (usually 1A - 5A is sufficient);

[0026] S3: Use a clamp ammeter to measure at point a. The current is almost the same as the output of the constant current source, and it is determined that the fault point is after point a;

[0027] S4: Use a clamp ammeter to measure at points b, c, and d respectively. No current is measured at points b and d, and the current at point c is almost the same as the output of the constant current source, and it is determined that the fault point is after point c;

[0028] S5: Use a clamp ammeter to measure at points e and f respectively. No current is measured at point f, and the current at point e is almost the same as the output of the constant current source, and it is determined that the fault point is after point e;

[0029] S6: Use a clamp ammeter to measure at point g respectively. No current is measured at point g, and it is determined that the fault point is between point e and point g.

[0030] Figure 1 is the schematic diagram of a method for quickly finding the fault point of a street lamp line described in Embodiment 1;

[0031] In actual use, the above steps can be repeated to gradually narrow down the range of the fault point until the faulty street lamp can be finally found.

[0032] Embodiment 2:

[0033] A method for quickly finding the fault point of a street lamp line includes the following steps:

[0034] S1: Refer to Figure 2 and Figure 3 , taking the AB two-phase short circuit as an example (since the judgment of fault types such as three-phase short circuit, two-phase short circuit, and single-phase grounding is relatively simple, this method will not be elaborated), disconnect the sub-switch of the AB two phases or remove the power supply wires of the AB two phases, and connect the constant current source to the power supply side of the AB two phases;

[0035] S2: Gradually increase the output current of the constant current source until it can be clearly observed using a voltmeter (it is recommended to use a pointer multimeter);

[0036] S3: Use a multimeter to measure at point a. By comparing with the voltage measured at the power supply side, the distance of the fault point can be roughly judged;

[0037] S4: Measure at point c with a multimeter. By comparing with the voltage measured on the power supply side, the distance to the fault point can be roughly judged.

[0038] S5: Measure at point e with a multimeter. By comparing with the voltage measured on the power supply side, the distance to the fault point can be roughly judged.

[0039] S6: Measure at point g with a multimeter. No voltage can be measured, and the fault point is between e and g.

[0040] Figure 2 is the schematic diagram of a method for quickly finding the fault point of a street lamp line described in Embodiment 2;

[0041] Figure 3 is the schematic diagram of a method for quickly finding the fault point of a street lamp line described in Embodiment 2 in actual use;

[0042] According to the circuit principle, when a constant current source is added, since the resistance at the fault point is much smaller than the resistance of the lamp, almost all the current flows to the fault point. Due to the very small resistance of the fault point and the power limitation of the constant current source, the voltage generated on the wire is not high, the lamp will not conduct and will not be damaged, and it will not cause harm to personnel. When approaching the fault point, the voltage may gradually decrease to a level that is difficult to measure. Therefore, it is recommended to use Embodiment 2 as an auxiliary means for Embodiment 1.

[0043] When using this method for measurement, depending on the type of load carried, the voltages at points b, c, e may not differ much, and the voltages at points e, f may not differ much. If the distance between e and g is relatively close, the voltage difference may be too small to observe. At the same time, voltage measurement usually requires contact measurement, and voltage measurement may be more difficult than current measurement. Therefore, this embodiment is recommended as an auxiliary means for Embodiment 1, and it is not recommended to use only this method for troubleshooting.

[0044] Comparative example:

[0045] Existing methods for finding the fault point of a street lamp line include the following steps:

[0046] Figure 4 is the schematic diagram of the comparative example in actual use;

[0047] Refer to Figure 4 , since the equivalent resistance of the LCD street lamp load is usually not large, and there are inductive components such as transformers in the LED driver, making its DC resistance very small, the difference between the faulty phase and the normal phase is not obvious when measuring the resistance with a multimeter or a megohmmeter, and it is difficult to distinguish. Therefore, the usual method for troubleshooting the street lamp fault point is as follows: (taking phase A grounding as an example)

[0048] Step 1: Energize the street lamp and check if phase A trips to judge that phase A is grounded;

[0049] Step 2: Cut off the power supply of the street lamp, disconnect the main line of the street lamp from any position (point a), re-supply the power, check if phase A does not trip, and the fault point is after point a;

[0050] Step 3: Cut off the power of the street lamp, connect the main line of the street lamp at point a, disconnect the main line of the street lamp at any position after point a (point b), re-supply the power, check if phase A trips, and the fault point is between points a and b;

[0051] Step 4: Cut off the power of the street lamp, connect the main line of the street lamp at point b, disconnect the main line of the street lamp at any position between points a and b (point c), re-supply power, check if phase A trips, and the fault point is between points ac;

[0052] .....

[0053] Repeat the above steps until the location of the street light can be determined.

[0054] When the route is long and has a tree structure, troubleshooting will be more difficult.

[0055] Results and discussion:

[0056] 1. Compared with the comparative example, the embodiment is simpler to operate, and there is no need to dismantle the street lamp line connection, which saves work intensity and maintenance time. At the same time, the street lamp power supply can be directly cut off without repeatedly stopping and supplying power, which saves manpower and is safer.

[0057] 2. Comparison between the method for quickly finding fault points of street lamp lines described in the present invention and the existing methods:

[0058] Compared with the method described in CN201811015251.1, there is no need to perform complex calculations, and there is no need to adjust the operating method according to the type of lamp and the power supply range. At the same time, it can also be applied to resistance lamps such as tungsten lamps and incandescent lamps. It has a wide range of uses, simple operation methods, and is easy to promote.

[0059] Since the method described in CN201811015251.1 directly uses 220V AC power for operation, when the capacitor is not selected appropriately, personnel may be exposed to high voltage and thus face the risk of electric shock. The AC constant current source used in this scheme has an open-circuit voltage that is the power supply voltage (usually below 24V, isolated from the 220V AC power by components such as a transformer). The parts that personnel can touch are all within the safe voltage and there is no risk of electric shock.

[0060] At the same time, compared with the method described in CN201811015251.1, this method does not require the use of a high-precision clamp ammeter and can be operated only with an ordinary clamp ammeter, greatly saving costs. At the same time, as mentioned in CN201811015251.1, for some fault conditions, the device will trip and only the original fault troubleshooting method can be used, with a limited scope of application. However, this solution has low requirements for the AC constant current source, and there are a large number of cheap and high-quality products available on the market.

[0061] The above description is a detailed description of the preferred feasible embodiment of the present invention, but the embodiment is not intended to limit the scope of the patent application of the present invention. Any equivalent changes or modifications made under the technical spirit disclosed by the present invention shall fall within the scope of the patent covered by the present invention.

Claims

1. A method for quickly finding the fault point of a street lamp circuit, characterized in that: The scope of application includes, but is not limited to, single-phase grounding, two-phase short circuit, three-phase short circuit street lamp line faults, and is applicable to, but not limited to, troubleshooting street lamp line fault points, including the following steps: S1: Connect an AC constant current power supply between the main line of the A-phase street lamp and the grounding electrode; S2: Gradually increase the output current of the constant current source to 1A - 5A, and it can be clearly observed using a clamp meter; S3: Use an ordinary clamp meter to measure the current output by the constant current source at the lamp post, and judge the location of the fault point according to the current mutation point.

2. A method for quickly finding the fault point of a street lamp circuit according to claim 1, characterized in that: The grounding electrode described in S1 is a grounding wire and a grounding stake.

3. A method for quickly locating a fault point in a street lamp circuit according to claim 1, characterized in that: The AC constant current power supply described in S1 has an open-circuit output of 24V or less.

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