Method for investigating leakage fault point of leakage protector

Test vote judgment

This method is mainly suitable for finding faults of the leakage protector itself, rather than external faults. First cut off the power supply, then remove the load side outlet of the leakage protector, and then turn on the power. If the leakage protector cannot be put into operation, the leakage protector itself is faulty and should be replaced or repaired. If the leakage protector can be put into normal operation, it means that there is no problem with the protector itself. At this time, the parameter settings of the protector should be carefully checked to ensure that the settings are correct, and then the power supply is cut off, and the outlets on the load side of the protector are all connected. Put into operation, if the protector is still not put into operation, it means that the line has fault leakage point. At this time, the leakage protector should be observed to confirm whether the cause of the trip is leakage or undervoltage, overcurrent, short circuit, electric shock. Preliminary judgment. If it is undervoltage, there is a problem with the power supply side line and equipment of the leakage protector. If it is leakage, overload, short circuit or electric shock trip, it is necessary to check the back line of the leakage protector. When the total leakage shows overcurrent trip, the solution needs to increase the capacity of the transformer. The total leakage protection should also be replaced with the model that matches the capacity of the transformer.

2. Article by item exclusion method

When it is confirmed that the fault point occurs on the outside line, the strip by strip method can be adopted. According to the order of “first trunk, re-branch, and rear end”, each branch line of the transformer station area is first disconnected, and only the main line is tested and sent. If the total leakage can be put into operation, the main line will be fault-free, then the main line can operate normally. Then, the branch and the end line are put into operation in turn, and when the line is put into operation, the protector takes action, and on which line the fault point is located, the fault point can be collectively found on the line.

3. House-to-house operation method

When it is confirmed that the fault point occurs in a certain branch line, the door-to-door operation method can be adopted, first all the subscriber lines of the line are disconnected, and then the leakage protector is put into operation. If the protector is not put into operation, it means that there is a fault on the line, and the line should be patrolled to find the fault; if the protector can be put into operation, it means that the fault is not on the line, but among the users, and then the user is changed by the user. When the user accesses the power grid, the protector trips when a user accesses, indicating that the user has a fault temporarily disconnected until all users in the radio station area have checked, and finally finds the fault point in the faulty user.

4. Instrumentation detection method

(1) Short-circuit detection method: disconnect the line switch of all users of the line, use the 500V megohmmeter or MF47-500 type multimeter to dial the pointer to R*10k file to check the fault. When it is checked that the resistance value of a certain line to a certain line or a line to the neutral line is less than 0.5 MΩ, there is a short circuit between the two lines. If it is a single-phase short-circuit fault away from the transformer, the user's light on the short-circuit line does not illuminate or the voltage becomes very low.

(2) Leakage detection method: In the case that the power grid is not powered off, firstly, the leakage clamp meter position is set to the AC 2A file, and the three-phase four-wire rear end of the leakage protector is fully inserted into the jaw to measure the total leakage of the power grid. Current, then the AN, BN, CN wires are respectively inserted into the jaws, the leakage current of each branch line is measured, and the branch line with leakage is found, and then one line and one zero wire are placed at each line of the line. Check the leakage current of each household completely into the jaws until the fault point is detected.

(3) Electric shock search method: First, disconnect all power supply loads, remove the neutral line, and connect a 200W incandescent lamp between the neutral line and the electrical phase line of the distribution box. Power transmission. After the lamp is on, use a clamp-type ammeter to measure the total test current in the neutral line. This current can be confirmed by measuring the neutral ground wire of the transformer. Then measure each line (A, B, C, N lines) of each branch line, record the data, and test the direction of the current in the neutral line. When there is test current on the phase line, the phase line There must be a leakage fault point. The second is to disconnect all the power supply load, split the zero line connection point of each line on the low voltage side of the transformer, and use the 500V megger or MF47-500 type multimeter to dial the pointer to the R*10k file to detect the zero line of each branch. If the resistance is less than 0.5MΩ or 0MΩ, the branch line neutral line has repeated ground faults.

5. "When you want to hear and cut" search method

The “Watching and Asking” search method is to perform visual inspection and inspection on the protection area including the leakage protector and the protected line equipment to find the leakage fault point.

“Wang” is to observe or measure the condition of each part of the leakage protector with eyes. If you look at the appearance of the leakage protector, there are no bumps and burns, whether the terminals have discharge marks and burnout, and whether the leakage protector readings are normal. Check whether the leakage protector is in good condition with the multimeter, and the inlet side is high and low. Whether the phase is missing, whether the high-voltage fuse and the low-pressure melt are intact.

"Smell" is to listen to the user's story, to understand whether the user's last-level leakage protector and the power equipment are abnormal, and see if the fault point occurs in the user's home. “Q” will take the initiative to ask the customer to know if there are hidden dangers and faults in the line equipment, so as to find the line equipment with hidden dangers and faults in time. "Cut" is to analyze and judge according to the information that is mastered, find out the line with faulty leakage point and conduct inspection inspection. During the inspection, attention should be paid to checking the complex sections and fault-prone points of the corners, branches, cross-overs of the line. This method is simple and easy to use, especially for fault finding with obvious points of failure. For example, the wires are intertwined, the communication cable is lapped, the wires are broken off the ground, the trees touch the wires, the wires are in contact with the wires, the porcelain bottles are severely damaged, and the user leakage protector is burnt out.