What is the method for detecting leakage of electricity from domestic lines?
"Electricity" is already an indispensable source of energy for our lives. In this season, with the gradual increase of temperature, rainy and humid weather has gradually increased, and there have been more reports of electrical leakage faults in our homes. For friends whose basic knowledge of electricity is zero, having a place to leak electricity at home is a big trouble! Hey! Hey! If you do not want to find the cause of leakage because of repeated search and trouble, then take a look at this culture and education everyone several home leakage fast detection methods!
"Leakage" is a certain potential difference between the housing of the electric appliance and the electric wire of the city due to some reason. First, find out what the fault phenomenon is, what are the obvious features, and then observe whether there is an intuitive fault point from the surface, and then carry out the next inspection. (The best way to detect leakage is to use an electric pen to contact the charged body. If the helium bubble lights up immediately, it will be extinguished, proving that the charged body is static electricity; If the long light must be leakage no doubt.) The following details the rapid detection of leakage of electricity:
Several common detection methods for electrical leakage
1. The power leakage fire alarm system is used to realize the alarm before the threshold value or to cut off the power supply of the line in time when the valve is straight; The leakage fire alarm system can be set up separately, or the leakage fire alarm system can be connected into an independent system according to the size of the building, and it can also be incorporated into the "Design Code for Fire Automatic Alarm System" to achieve centralized display and control.
2. Periodic detection of the leakage current of the target line of low voltage distribution using a clamp-shaped leakage current meter
3. In the area where the telephone and cable are concentrated, the changes in the spatial gas composition and concentration around the wire and cable are monitored by means of an suction alarm, so as to achieve the purpose of judging whether the insulation material is overloaded with heat decomposition; The thermal decomposition of the insulating material is used to determine whether the cable wires leak or not.
General family lines, the power leakage points, but also divided into zero line leakage, if the method, see the specific situation:
Due to the long service life of the electric line, it will cause insulation aging, insulator damage, insulation layer dampness or wear and so on, resulting in leakage of electricity on the line. At this point, an ammeter is connected to the total knife gate, the load is removed, and the load switch is connected.
If the meter pointer swings, the line leaks. Cut off the zero line, if the meter pointer does not change, indicating that the fuse and the earth leakage; The meter pointer is returned to zero, indicating that there is a leakage between the fuse and the zero line;
If the current meter indicates that it is smaller but not zero, it indicates that there is a leakage between the fuse and the zero line, the fuse and the earth.
Remove the partition fuse or open the knife gate, and the constant current meter indicates that the bus is leaking;
The current meter indicates that the power leakage is zero. The current meter indicates that it is smaller, but it is not zero, indicating that both the bus and the partition leak.
After determining the power leakage, pull the switch of the line in turn. When a switch is pulled off, the current meter indicates zero, indicating that the line leaks electricity;
If it becomes smaller, there is also a leakage of electricity outside the line;
If the switch is closed, the leakage switch will trip. This type of fuse leaks electricity. The inspection method is as follows:
1. Determine whether the line leakage method
First, all the switches are disconnected, then the main gate is closed, and then the switches are closed in turn. If there is a problem, the leakage switch will be disconnected.
2. To determine whether the electrical leakage method
First unplug all the electrical appliances and then plug them into the plug. That appliance causes a trip. Then the appliance that caused the trip is obviously malfunctioning.
3. Determine whether the zero line leakage
Turn off all the lights, turn on the lights one by one, and turn on which light to cause the jump, that is, there is a problem with the light(or line). If the gate is closed, it does not immediately jump, and the time is long, it will jump, and the time of the jump is inconsistent. This is a zero-line leakage. The inspection method is more professional and uses a megabyte watch(if all the electrical appliances on all sockets are unplugged, the problem should be on the line)
Methods: The main zero line was first taken apart, all the switches were disconnected, and the zero line insulation of each line was checked one by one with the Zhaoou table to find out the problem line. Then look at which electrical appliances on the line are directly connected(such as electric lights or certain air conditioners, etc.) and check them separately. If you don't care about electrical appliances, the line is out of order and you can only change the line.
4. Meter discrimination
The long service life of the line, and the long-term wet and worn environment of the line will lead to aging of the insulation layer and damage of the insulator, resulting in leakage of electricity on the line. To determine a similar situation, attach an ammeter to the general knife gate without any load and switch on the load. If the meter pointer swings, the line leaks. When cutting off the zero line; If the meter pointer does not change, the leakage phenomenon occurs between the fuse and the ground; If the current representation is zero, a leakage phenomenon occurs between the fuse and the zero line.
5. Magnetic needle discrimination
Due to the electromagnetic induction phenomenon, the test wire is leakage, and a magnetic pointer can be placed at the test site. When the pointer direction is offset, it indicates that the test site is leakage.
6. If the current represents a smaller number, but there is still a value, it indicates that there is a leakage between the fire and the fire.
Remove the partition fuse or open the knife gate. If the current meter indicates that it is unchanged, it can prove that it is a bus leakage; The current meter indicates that the power leakage is zero. The current representation becomes smaller, but it still has a value. It can be concluded that both the bus and the partition have leakage. When we determine the leakage branch, we will disconnect the branch switch in turn. When the disconnection current representation of a certain switch becomes zero, we can judge the leakage of the line; If only the number of indications becomes smaller, it is not only the leakage of the line; If the main line leaks electricity, all switches are disconnected and the current representation is unchanged.
7. Determine whether the lighting line leakage method
First turn off all the lamps and then turn them on in turn. If that lamp causes a trip, it is very likely that the lamp or the lamp's line is malfunctioning. The total switch jumpers, sockets and lighting each use an empty switch, and then the total switch does not jump after the light is turned off. It is suspected that the lighting line is leaking.
When the lighting loop is closed and the other circuits(sockets) are running, the total switch does not jump, indicating that the fault range is in the lighting loop. The following steps can be taken:
1. Disconnect the lighting loop and remove the 2 leads in the lower part of the circuit.
2. Use a multimeter to measure the ground insulation resistance of two leads respectively, confirm the failure range again, and determine which of the wires is poorly insulated to the ground.
3. According to the situation on the spot, check the entire lighting circuit from simple to complex.
4. Attention should be paid to the use of professional theory and work skills. You can disconnect "points" that are "convenient, necessary, and reasonable" in the loop, and then measure the insulation resistance to the ground in sections. This will gradually reduce the failure range, and finally find the fault point and eliminate it.
5. For new buildings, there is generally no problem with the main lighting line. Therefore, priority should be given to switching the box and the top light connection. In addition, It is also necessary to consider whether there are problems with the use of electric drill slots, holes(such as ceiling) and self-added lines. WeChat Search: AZPT991 Building Hydropower Knowledge Platform and Thousands of Electricians Learn and grow together
8. Use a multimeter to quickly check leakage of electricity
1). Disconnect the total isolation switch of the user's power feed first, and close all user's power load, such as unplugging the refrigerator plug, disconnecting the pump switch, etc..
2). Place the digital multimeter on Oumudang's 200M block, one watch pen on one of the two qualifying lines on the side of the load, and the other watch pen touches the wall. It is best to touch the ground line. Or temporary ground line. After the number displayed on the iso-multimeter is stable, the value of the insulation resistance of the main line is read out. If the insulation resistance value is less than 0.5 megaeuros, then the main line has a problem. If the insulation resistance is more than 0.5 megaeuros, That would rule out a problem with the main line. Use the same method to measure the other wire and also look at the value to see if there is a problem with the main line.
3). The insulation resistance values of the separation and various electrical appliances are also tested in the same way one by one until the fault point is found.
4). If the gate of the leakage switch is closed immediately, the leakage of electricity will generally occur in the "FireWire"; If the gate is closed after a period of time and the duration of the trip is not necessarily the "zero line" leakage situation.
1. When using a multimeter Oumudang's 200M block, note that you can not touch the metal part of the pen with your hand when measuring, which will make the reading inaccurate.
2. When measuring various electrical devices, pay attention to discharge first to prevent capacitive current in the equipment.
This method is a safer way to find the fault point in the absence of electricity. This method also applies to the search for power users and plant leakage, but when searching, not only should the power supply be disconnected, but also the zero line should be disconnected to avoid electric shock accidents.