Induction and leakage

Update date:2018-06-23 Source:MAXGE

Inductive charging is caused by the mutual induction of the line and the case inside the machine or the mutual induction between the line and the line, which is equivalent to the capacitance between the live part and the case. Leakage is due to the use of the machine for a long time or moisture and other reasons caused by the insulation of the internal line insulation or reduced insulation, making the machine shell charged. Some are caused by the deformation of the outer shell of the machine, causing the shell and the internal charged part to have direct contact with one or more places (in which case it is dangerous to re-use the machine).

Residual Current Operated Circuit Breaker

The judgment method

1, resistance measurement

Use a multimeter to measure the insulation resistance between the machine housing and the circuit. When the measured resistance is greater than 1M, it can be considered as a live induction. When the resistance of the measurement is several thousand ohms or less, it can be considered as a leakage, taking measures. Caixing. This is a simpler method than the most commonly used method, but this method is not very reliable and must be further determined by other methods.

2, the load judgment method

Disconnect the machine's neutral line (N line) and connect a 220V/15W light bulb between the breakpoint and the housing. After connecting well, turn on the power. If the light bulb is glowing, it indicates that the machine has leaked; if the light bulb does not shine, it indicates The machine is inductively charged. This is because the leakage current can be large enough to make the light bulb emit light, and the induced current is only a few tens of milliamps, which is not enough to make the light bulb shine. This method is more accurate.

Residual Current  Circuit Breaker

3, voltage measurement method (1)

With the multimeter's voltage block, first measure the voltage between the machine housing and the ground, then reverse the line (L line) and the neutral line (N line) of the machine, and then measure the voltage between the machine housing and the ground. If there is a large change in the voltage value between the previous and the next two times, the leakage is caused to a great extent; if there is no obvious change in the two measurement results, it means the induction is charged. This is because the leakage point occurred in the machine is often not in the middle of the normal charged body of the machine. If it happens to be exactly in the middle, an error will occur. The results of the two previous and subsequent measurements will be different. When the sensor is charged, the value does not change because it is independent of the measurement point.

4, voltage measurement method (2)

When the machine is running, use a multimeter to measure the voltage between the machine housing and the neutral wire (N line). Stop the machine, disconnect the neutral line (N line), connect the multimeter between the breakpoint and the machine shell, then connect the live line (L line) to the power supply only, measure the voltage again, compare it twice before and after, if the result is twice There are obvious changes, it shows that it is leakage; if there is not much change, in most cases it is caused by induction. This is because the voltage measured for the first time is the voltage between the leakage point and the neutral line (N line) (unless the leakage point is close to the line end and is approximately the supply voltage), the second measured voltage is basically the supply voltage; There are many differences between the two. There is no such change in value if it is inductively charged.

5, voltage measurement method (3)

Put the digital multimeter on the AC20V block, then hold one of the pens with one hand, and the other with the other pen near the machine case. When the distance is about 4-5cm, observe the multimeter. If the multimeter shows a voltage of several volts (V), it indicates that the leakage is caused by the leakage. If the multimeter does not display or the displayed value is very small, it indicates that the shell is charged because of induction. of.

Circuit Breaker

Judging from the above methods of judgment, some are simple and some are not very accurate.Residual Current Operated Circuit BreakerTherefore, when encountering a situation where the casing of the machine is live, several methods must be used in conjunction with each other to judge, in order to increase the reliability of the judgment, so as to take corresponding measures. Measures.


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