How to detect the leakage point of the cable, how to measure the leakage of the wire with electricit

Cable leakage points can generally be detected by a leakage tester, but if you don't have this instrument at hand, you have to use a multimeter.

Detect. Make a self-made leakage detection device, bend the iron wire into a circle just enough to pass through the cable, and then open the resistance of the multimeter by 10k position, pass the cable through the iron ring, one of the watch pen is connected to the iron ring, and the other is connected to the copper core wire of the cable. When the multimeter hand turns, it means that the leakage point is there.

Specifically, there are the following proven methods:

1. Check along the cable, find the location of the cable damage, and repair the exposed electricity;

2. The battery cell will be exposed.

The wire is interchangeable with the grounding core wire to make the cable work normally;

3. According to the principle of potential drop, find out the approximate location of leakage. It is the AC voltage level of the multimeter, because the potential drop is spherical;

4. Use step voltage.

When the power cable leaks to the ground, it will produce a directed electric field gradient from strong to weak around the fault point on the ground. The amplitude and direction of the signal can be measured along the cable path with Baoshuntong cable fault measurement equipment.

Before and after the fault point, the direction of the galvanometer pointer is opposite, and then the fault point of the cable is found to achieve the purpose of accurate positioning. Since the electric field signal between two points on the ground is measured, it is usually called the step voltage.

Second, the detection of fireproof cable faults generally goes through three steps: diagnosis, ranging, and fixed-point.

1. Diagnosis of the nature of cable fault The diagnosis of the nature of cable fault, that is, to determine the type and severity of the fault, so as to facilitate the tester to prescribe the right medicine and select the appropriate cable fault ranging and fixed-point method.

2. Cable fault ranging Cable fault ranging, also known as rough measurement, uses an instrument to determine the fault distance at one end of the cable, and the commonly used fault ranging methods on the field include the classical bridge method and the modern traveling wave method.

3. Cable fault fixed-point Cable fault fixed-point, also known as precision measurement, that is, according to the fault ranging results, according to the path direction of the fireproof cable, find out the general location of the fault point, and use discharge acoustic measurement or other methods to determine the accurate location of the fault point in a small range. Generally speaking, successful cable fault detection must go through the above three steps, otherwise it will not be achieved quickly.

The cable leakage point detection method and process are as follows:

1. Diagnosis of cable fault nature.

Diagnosis of the nature of the cable fault, that is, to determine the type and severity of the fault, so that the tester can prescribe the right medicine and choose the appropriate cable fault ranging and fixed-point method.

2. Cable fault ranging.

Cable fault ranging, also known as rough measurement, uses an instrument to determine the fault distance at one end of the cable, and the commonly used fault ranging methods on the field include the classical bridge method and the modern traveling wave method.

3. Cable fault point.

Cable fault fixed-point, also known as precision measurement, that is, according to the fault ranging results, according to the path direction of the cable, find out the general location of the fault point, in a small range, the use of discharge acoustic measurement or other methods to determine the accurate location of the fault point.

You can consider the cable fault multi-function tester of the original Huaxiang Century Electronics, breakpoint, short circuit, leakage grounding, path direction finding, and length test. The model is HS-T880 Plus, upgraded, high and low voltage, armoured cables and unarmoured cables can be tested.

Leakage: The insulation between the phase line of the cable and the ground is destroyed, resulting in the operation of the line leakage protector. This fault is detected in conjunction with a signal generator.

After the fault of the line, you should first use tools such as megohmmeter and multimeter to determine the nature and severity of the line fault, and find out the corresponding fault line, so as to select the appropriate test method.

Testers know where the line is going and what the fault is going to do, which helps to quickly identify the point of failure. When the cable fails, the time of the fault, the scope of the fault, the environment where the cable line is located, the location of the joint, the influence of the weather and the possible problems are comprehensively considered. Based on the results of the measurements, a rough judgment of the faulty passage is made.

1 Select a test method:

When the fault resistance is less than a few hundred to several thousand ohms, we call it a low-resistance fault, and vice versa, it is called a poor insulation or high-resistance fault. There is no clear boundary between high and low resistance.

The length test is suitable for testing disconnections and low-impedance mixed-wire faults. Serious insulation defects. The length test is intuitive, easy to operate, does not require an end-to-end fit, and should be used first when testing.

2 Fault ranging:

During the test, the equipment connected to the fault line pair should be disconnected first, the line head is suspended, the test line is connected, and the automatic key test is pressed for obvious disconnection and short circuit faults, and both ends of the line should be tested to facilitate the precise location of the fault point.

3 Fault Points:

According to the results of the instrument test, the location of the specific fault point is calibrated according to the line data. When the line direction is not understood, the accurate line direction is detected by cooperating with the signal generator, and then the fault cause is analyzed according to the fault situation and the surrounding environment until the fault point is found. The shorter the measuring range, the smaller the measurement error.

This method can detect single-core cables, if it is a multi-core cable, it is necessary to change to another method.

Diagnose the nature of the cable fault, determine whether it is a high or low resistance, whether it is an internal or closed fault, whether it is grounding, short circuit, broken wire, or a mixture of them, whether it is a single-phase or two-phase, or three-phase fault.

Turn off all electrical appliances, if the meter is still turning, it means that the line is leaking. As for where the leakage is, it can be tested with the help of an electric pen. Measure with an optical gauge, but need to disconnect the load, each circuit should be measured separately, such as measuring a point to the ground resistance is very low, the side indicates that the leakage is serious.

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Hello! How to detect ground wire leakage? First of all, how much voltage should I measure? The voltage is high close to 220V, indicating that the ground wire and the earth are disconnected, and the leakage generated by the useful electrical appliances at home is transmitted to the ground wire through the shell, but the ground wire binding post does not enter the ground, and this wire becomes a charged body.

Inspection method: turn off all the output switches in the electric box, measure whether there is voltage between the fire and the ground under the main switch, send the gate one by one, especially if there are three wires plugged in the wall, and it is easy to find out the leakage one by one.

The best way to detect leakage is to contact the charged body with an electric pen, and if it turns on once, it will go out immediately, proving that the charged body is static; If it is always bright, it is undoubtedly leakage.

What I just said is measured with an electric pen; You can also use a multimeter to ground the wire at one end, and plug it into the ground to detect whether there is a voltage display? Take a longer wire, one end of the line is plugged into the grounding wire at the total incoming wire in the distribution box at home, the other end is on a meter rod of the multimeter, the other meter rod of the multimeter is placed on the grounding wire end of the socket to be detected, the multimeter is adjusted to the 1 of the ohm file, if the meter shows that the measured resistance is not greater than 4 ohms, the grounding is normal! The multimeter hits the AC file, determine the jack of the zero line and the live wire, generally the three-hole plug is the left zero and the right fire on the ground, measured separately, if the voltage difference between the fire and the ground is equal to the fire zero voltage difference, it means that the grounding is good, if it is zero, the ground wire is empty, if the voltage is less than the fire zero voltage difference.

It indicates that the grounding is not true and there is a grounding resistance.

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Disconnect all the sub-switches, close the main switch, close the sub-switches one by one, close to that, and the leakage switch will jump, that is, there is a problem with that road.

Maintenance method, in turn, disconnect the back wiring of each socket, respectively energized test: disconnect the electric switch, disconnect all the wiring behind the furthest first socket, remember the position, and close the test. If it still cannot be closed, disconnect all the wiring behind the second, third, and fourth sockets in turn.

Knife switch and air switch: its function is to control the on-off of the whole family circuit, installed on the trunk road, when installing the knife switch, the upper end is a static contact connected to the input wire, and must not be reversed.

Inlet line: The inlet line is divided into end wire (a phase wire in the three-phase four-wire circuit is generally red, commonly known as live wire) and neutral line (the zero line is the line drawn out of the neutral point of the transformer, and the phase wire forms a circuit to supply power to electrical equipment), and there is a voltage of 220V between the live wire and the neutral line (110V voltage in some countries).

They constitute the power supply of the home circuit (the live wire and the earth have a voltage of 220V, the neutral line and the earth have no voltage), they use the voltage tester to judge, the neon tube that can make the tester shine is the live wire, and the neon tube can not make the neon tube shine is the neutral line. The ground wire also does not make the neon tube glow (the metal nut of the tester should be in contact with the hand. (Left zero right fire).

The above content reference: Encyclopedia - Home Circuit.

Summary. There are two ways to use a multimeter to measure whether the wire leaks from the ground: one is live measurement, the multimeter is adjusted to the AC file, and the voltage between the equipment shell and the ground is measured in the case of the equipment being energized.

This test is generally not recommended.

There are two ways to use a multimeter to measure whether the wire is leaking to the ground: one is the hidden species is live measurement, the multimeter is adjusted to the AC file, and the voltage between the equipment shell and the ground is measured in the case of the equipment being energized, and the voltage is generally induced by tens of volts, and the equipment can be determined to have leakage if it exceeds 100 volts. This method of detecting suspicion is generally not recommended.

The second method is to disconnect the power supply and measure the insulation resistance of the live wire and the neutral wire and the ground wire. If you use a multimeter to measure, generally the leakage is more serious can be displayed on the multimeter, and the resistance value is generally in the range of hundreds of ohms to tens of ohms. Digital Multimeter Measurement Method:

1. The multimeter is adjusted to AC gear, in the case of the equipment is energized, measure the voltage between the equipment shell and the ground wire (determined to be the ground wire), if the voltage range is tens of volts or 110 volts, it means that it is induction, if it is 220V or 380V, it means that it is leakage. 2. The multimeter is adjusted to the AC file, in the case of the equipment is energized, measure the voltage between the equipment shell and the neutral line, if the voltage range is tens of volts or 110 volts, it means that it is induction, if it is 220V or 380V, it means that the Heng Xuan macro is leakage. However, strictly speaking, the measurement of whether the circuit insulation resistance of the circuit leakage should use a shake meter, which is equivalent to a 1000V or 500V generator, and the leakage current passes through the sampling resistance inside the shake meter, and the sampling voltage indicator is generated on the resistance.

Normally, a stable greater than megaohm is qualified. The method is as follows: 1. Turn off the power of the equipment, fully discharge, do a good job of safety measures and hang reminder signs, and then untie the terminals on both sides of the cable to be tested.

The equipment is never allowed to be charged for measurement, so as to ensure the safety of people and equipment. 2. Before measuring, check whether the megohmmeter is in normal working condition, mainly check its "0" and "" two points. That is, shake the handle to make the motor reach the rated speed, the megohmmeter should be pointed to the "0" position when the short circuit is short, and the "" position should be in the "" position when the open circuit is open.

3. L" line end button is connected to the conductor of the equipment under test, "E" ground end button is grounded to the equipment shell, "G" shield is terminated to the insulating part of the equipment under test, and the meter is rotated at an average speed of 120 revolutions.

In the absence of leakage, all the current flowing out of the live wire at the power supply inlet line returns to the neutral line. When leakage occurs, the amount of current coming back is different. Due to the long service life of electrical circuits, it will cause insulation aging, insulator damage, moisture or wear of the insulation layer, etc., and leakage on the road.

At this time, connect an ammeter on the main knife switch, remove the load, and turn on the load switch.

1. If the pointer of the ammeter swings, it means that the line is leaking. cut the neutral line;

2. If the pointer of the ammeter remains unchanged, it means that there is leakage between the live wire and the earth;

3. If the pointer of the ammeter returns to zero, it means that there is leakage between the live wire and the neutral line;

Judging whether the wire is leaking is actually very simple, the old electrician will detect it in kind, and you will learn it.

First of all, the wire is in the conduit in the wall, how do you know that the wire has leaked?

Generally, the wire is in the protective tube, and there will be no leakage, and it will only leak after being damaged by external force.

Therefore, if there is no external force to damage, the wire leakage, other reasons should be investigated.