It is very easy to use a multimeter to measure a short circuit. Using a multimeter to measure ground is not very accurate. In fact, it makes the most sense to use an oscillating meter,how to test pcb board with a multimeter and here's how to use a multimeter to check a circuit for a short or a leak.

A word to you about short circuits:

As we know, a short circuit in a line is a connection between phases and between phases and between phases and ground outside of the normal operation of a power system;

So the grounding of the phase wires is also considered a short circuit of sorts, and the zero wire will develop a leakage current and trip the leakage protector if the system is not grounded.

How to detect a short circuit in a line with a multimeter;

When detecting a short circuit in a technical line with a multimeter, we teachers first disconnect the power supply, disconnect all work loads, and then analyze and detect them;

When the multimeter detects a short circuit in the line, the black needle terminals are connected to the COM hole, and the red needle terminals are connected to the VΩ hole, open the digital multimeter, we have to choose to measure the diode that is, the line conduction that gear;

The method is to use the black needle to contact the fire line, and the red needle to contact the zero line. If the multimeter buzzes or indicator flashes, it means that the line is through, that is, short circuit, and vice versa. Measure the ground and earth with the same operation, showing the same as above.

Measure the line leakage with a multimeter:

Measuring line leakage with a multimeter is not very accurate, but it can be measured;

Multimeter to detect leakage in the technical line, the black meter needle terminals connected to the COM hole, the red meter needle terminals connected to the VΩ hole, open a digital multimeter, we have to choose to pass the measurement of the system line as well as the resistance of that gear;

If the measured value is greater than 0.5 megohm or display to infinity, the line insulation is not a problem, that is, there is no leakage; if the measured value is less than 0.5 megohm, the line insulation is not qualified, there is a leak.

Many electricians will tell you to cut off all the power, with the minimum resistance file (or diode file) to measure the resistance between the two wires to see if it is close to 0 ohms (or diode file shows 0). If it's close to 0, you can basically tell that the two wires are shorted together. Similarly, measure the distance from this wire to ground and see if the same thing happens. If it is proved that this wire is grounded, this method is certainly feasible, but the actual work of many places power outage is not convenient.

1. Suppose you want to measure for a short circuit between wires A and B. The voltage between wires A and B may be zero (e.g., 220 volts). The potentials on these wires are A and B. The first thing that comes to mind is that if you measure directly with a resistor, you must disconnect the power to A and B before measuring them. There is nothing wrong with this idea, but it is too conservative.

2, directly dial the multimeter to AC voltage range, select the highest range, such as AC1000 volts, and then use the AC voltage range of the multimeter to measure the A line and B line, if there is a relatively high voltage between the two lines (for example, 200 volts), it can be proved that the A potential and the B potential is not equal, that is, there is a voltage difference between the A potential and the B potential, the potential of the two lines is not equal, not together with a short connection! .

3, if the line A and line B use to carry out AC work voltage file measurement technology does not have a voltage, in order to be able to ensure safety, and then choose the DC system voltage file, such as 1000 volts to measure as well as between their development, to confirm that they do not have DC voltage, this kind of research can be proved that the potential of A and the potential of B are equal, pay attention to equal does not mean that they are on the zero line N did not get the voltage, oh, for example, line A and line B on the zero line N are 220 volts, but for the voltage between their countries at the same time is 0 volts, this problem when, you can use the smallest resistance gear to measure the resistance between the two lines management, if we approach 0 ohms, that the two lines are shorted together.

For the measurement of grounding, simple can also use the above measurement method, the idea is to understand the ground as a common line. However, the general measurement of whether the contact with the ground, you can use a shaker to measure the insulation resistance (generally insulated for 5 megohms) , which requires the measurement of the power off.

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