How to use a multimeter to check line breaks and short circuits
First of all, connect the pen, the choice of multimeter can be a pointer can also be a digital display, the red pen inserted into the VΩ file, the black pen inserted in the COM terminal, to ensure that the multimeter is normal; rotate the multimeter gears, measurement of short circuits or circuit breaks should use resistance gear, such as 200Ω file; will be connected to the line both ends of the pen, the multimeter does not show (show 1) for the circuit break, show 0 point a few of the small number for the short circuit.
Leakage should not be measured with a multimeter, multimeter power supply is generally a 9V battery, low voltage does not leakage does not mean that 220 high-voltage does not leakage, to be measured with at least 500V shaking table, shaking table of the two collets connected to the line at the end of the 2, shaking the handle, the meter head pointer to the direction of the zero direction to run for the leakage.
The three elements of the circuit is the power supply, load, intermediate links. The power supply is the device to provide electrical energy to the load, the load is the device to obtain electrical energy, which is converted into other forms of energy, the intermediate links of the switch is to open or close the circuit, the wire is the transmission of electrical energy.
Simply put a short circuit is the lack of load, only the power supply, the intermediate link of the two elements. While a broken circuit is the lack of intermediate links, only the power supply and load two elements, such as the switch is not closed, the wire is disconnected. Leakage is charged equipment or devices due to the aging of the insulation or other reasons lead to current leakage, due to some reason connected to the earth after a certain potential difference between the earth, which is leakage. Therefore, leakage may occur in the power supply unit, may occur in the load, may also occur in the intermediate links.
Checking short-circuits, circuit breaks, and leakage with a multimeter
Check short-circuit and disconnection faults with the resistance check method or check short-circuit and disconnection faults with the buzzer gear.
When checking for short circuits and breaks with a multimeter and using the resistance check method, make sure that the power supply to the circuit is disconnected. When checking the load or line, select the appropriate resistance gear. Found that the multimeter reading is zero, the multimeter gear down, or the reading is still zero, there must be a short circuit. The reading shows the overflow symbol "1", adjust the resistance level upward, or show the overflow symbol "1", there must be a broken circuit. With the multimeter beeping gear to check short-circuit and disconnection, the premise is also to cut off the circuit power. If the multimeter beeps during the test, there must be a short circuit. If the display of the overflow symbol 1 is not necessarily disconnected, this time in the multimeter with a large resistance gear to continue to measure, if it still shows the overflow symbol 1, indicating the existence of disconnection.
Multimeter check leakage
According to the statement of leakage can be seen, due to the load, power supply units, intermediate links in the insulation layer aging or other reasons lead to current leakage, then the above three elements will be with the earth between the potential difference. If tested with a test pen, its neon tube will certainly glow continuously. When checking with a multimeter, one of the pens is connected to the metal casing of the power supply unit or equipment casing, etc., and the other pen is connected to the earth, and there is a voltage between them. The size of the multimeter reading indicates whether the leakage current leakage of one of the three elements, load, intermediate link, and power supply unit, is serious.
Among them, to measure the leakage of the best results. At this point, look for a good grounding point at the location being tested, such as a well pipe, damp earth, and other good grounding points. Then lap one of the pens of the multimeter to the shell of the electrically charged body being detected, and lap the other to the selected grounding point. In this way, the leakage effect of detection is more obvious.
