Method for searching leakage fault point by using bypass current of neutral line of low-voltage power supply line
Technical Field
The invention relates to the technical field of fault processing of low-voltage power supply circuits of power supply systems, in particular to a method for searching a leakage fault point for a bypass current of a neutral line of a low-voltage power supply circuit.
Background
The method is characterized in that after a protector is switched off due to electric leakage of a power supply station area circuit (including a client circuit and an electric appliance) in the rural area, a leakage fault point is searched for, and generally, a megameter, namely an insulation megger, is used for searching for the leakage fault point, but only a client circuit part can be measured, otherwise, a circuit connection point is required to be disassembled, so that the method is very troublesome and time-consuming; at present, forced power transmission is generally adopted, leakage current is measured by a high-resolution clamp ammeter in a charged state, and only an insulated service wire and the parts below the insulated service wire can be measured, because the function of circuit outage and leakage protection is very unsafe.
In summary, the research and development of the method for finding the leakage fault point by using the bypass current of the neutral line of the low-voltage power supply line still remains a key problem which needs to be solved urgently in the technical field of the power system.
Disclosure of Invention
The invention aims to provide a method for searching a leakage fault point by using a bypass current of a neutral line of a low-voltage power supply circuit, which solves the problems in the background art.
In order to achieve the purpose, the invention is realized by the following technical scheme: the method for searching the leakage fault point by the bypass current of the neutral line of the low-voltage power supply circuit comprises the following steps:
s1, measuring the neutral current I at the position of the I-loop outgoing line switch with the brake droppedL2;
S2, measuring the neutral current at the middle position of the I loop, if the neutral current is far less than IL2Numerical values, indicating that the failure point is nearly halfway, if approaching IL2A numerical value, which indicates the line after the fault point is at this position;
and S3, directly measuring the current of the service line and the service line loop after locking the fault section according to the method, and finding out a fault point.
Further, in operation S2, the neutral current is much less than IL2The value is measured at the middle of the first half of the I-loop, if it is still much smaller than IL2A numerical value indicating that the failure point is still at the front end; if approaching IL2The numerical value indicates the distance between the line and the intermediate measurement after the fault point.
Further, in operation S2, the neutral current approaches IL2The value is measured at the middle of the latter half of the I-loop, if it is much smaller than IL2Numerical values, which indicate that the failure point is at the front end; if approaching IL2The numerical value indicates the line after the fault point is at this position.
The invention provides a method for searching a leakage fault point by using a bypass current of a neutral line of a low-voltage power supply circuit. The method has the following beneficial effects:
the invention does not need complex equipment, is safe and convenient for finding fault points after power failure, explains the problem of mutual influence of outgoing lines of the leakage protector, and prevents the trouble of frequent power failure in a transformer area caused by blind trial transmission during power transmission of people.
Drawings
Fig. 1 is a circuit diagram of a low voltage power supply line.
Detailed Description
As shown in fig. 1: the method for searching the leakage fault point by the bypass current of the neutral line of the low-voltage power supply circuit comprises the following steps:
step one, measuring neutral current I at the position of an I loop outgoing line switch which is switched offL2。
Step two, measuring the neutral current at the middle position of the I loop, if the neutral current is far less than IL2Numerical values, indicating that the failure point is nearly halfwayIf approaching IL2The numerical value indicates the line after the fault point is at this position.
If the neutral current is much less than IL2The value is measured at the middle of the first half of the I-loop, if it is still much smaller than IL2A numerical value indicating that the failure point is still at the front end; if approaching IL2The numerical value indicates the distance between the line and the intermediate measurement after the fault point.
If the neutral current is close to IL2The value is measured at the middle of the latter half of the I-loop, if it is much smaller than IL2Numerical values, which indicate that the failure point is at the front end; if approaching IL2The numerical value indicates the line after the fault point is at this position.
And step three, directly measuring the current of the service line and the service line loop after the fault section is locked according to the method, and finding out a fault point.
In summary, it is shown that: when the leakage current of the loop II flows back to the neutral point of the transformer through the ground, the loop I is connected with the ground in parallel due to the ground fault, and a bypass current I is formed on the neutral line of the loop IL2,Looking up to form this bypass current IL2The position of the fault point can be locked, the novel method for searching the fault point of the switching-off loop by the neutral line bypass current does not need complex equipment, the fault point can be searched safely and conveniently after power failure, the problem that the outgoing line loops of the leakage protector influence each other is explained, and the trouble that people try to send power blindly when power is transmitted to cause frequent power failure in a transformer area is prevented.
The above is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, many variations and modifications can be made without departing from the inventive concept of the present invention, which falls into the protection scope of the present invention.