How to measure leakage with a digital multimeter
The battery inside the multimeter is 9v to 15v. The resistance and voltage files can only determine the short circuit, and roughly judge whether there is leakage.
There are three ways to check leakage with a multimeter:
1. Power-off measurement: turn off and disconnect all electrical appliances, use a multimeter with RX10K gear, one test lead is connected to the live wire, and the other test lead is grounded (or faucet). It should show infinite resistance, otherwise there will be leakage.
2. Live measurement: Use a multimeter with a 250-volt AC voltage range to measure the metal shell of the electrical appliance that is suspected of leakage. One test lead is connected to the shell, and the other test lead is grounded (or the faucet). When the pointer shows a voltage higher than 30-50 volts, replace it Use AC 50 volts. If the power supply is confirmed to be higher than 30 volts, it is a leakage, and lower than 30 volts is normal. Then swap the zero and fire power supply plug wires and measure again to confirm.
3. Leakage measurement between live wire and neutral wire (or live wire and live wire): turn off and disconnect all electrical appliances, measure the resistance between live wire and neutral wire, it should be infinite, otherwise it is leakage.
Check the leakage method with a digital multimeter as follows:
1. Use the ohm gear of the multimeter (R×10k or R×1k grade, depending on the capacity of the capacitor), when the two test leads touch the two lead wires of the container, the hands of the meter first face clockwise (to the right) Swing, and then slowly return to the left near the ∞ position, this process is the charging process of the capacitor.
2. The resistance value pointed to when the needle is stationary is the leakage resistance (R) of the capacitor. If the watch needle is far away from infinity during the measurement, it indicates that the capacitor has serious leakage and cannot be used. When measuring the leakage resistance of some capacitors, when the pointer returns to the infinity position, it swings clockwise again, which indicates that the leakage of the capacitor is more serious. It is generally required that the leakage resistance R≥500k, otherwise it cannot be used. 3. Note: For capacitors with capacitance less than 5000pF, the multimeter cannot measure its leakage resistance.
Multimeters, also known as multimeters, multimeters, three-meters, multimeters, etc., are indispensable measuring instruments in power electronics and other departments. Generally, the main purpose is to measure voltage, current and resistance. Multimeters are divided into pointer multimeters and digital multimeters according to the display mode. It is a multi-functional and multi-range measuring instrument. Generally, the multimeter can measure DC current, DC voltage, AC current, AC voltage, resistance and audio level, etc., and some can also measure AC current, capacitance, inductance and semiconductor. Some parameters (such as β) and so on.
Basic function
The multimeter can be used not only to measure the resistance of the measured object, but also to measure the DC voltage. Some multimeters can even measure the main parameters of transistors and the capacitance of capacitors. It is one of the most basic skills of electronic technology to be fully proficient in the use of multimeters.
Common multimeters include pointer multimeters and digital multimeters. The pointer multimeter is a multi-functional measuring instrument with the meter head as the core component, and the measured value is read by the pointer of the meter head. The measured value of the digital multimeter is directly displayed in digital form by the liquid crystal display, which is easy to read, and some also have a voice prompt function. A multimeter is a meter that combines a voltmeter, an ammeter and an ohmmeter in one head.
The DC current file of the multimeter is a multi-range DC voltmeter. The voltage range can be expanded by connecting the closed-circuit voltage dividing resistor in parallel with the meter head. The DC voltage file of the multimeter is a multi-range DC voltmeter. Connecting the voltage dividing resistor in series with the meter head can expand its voltage range. Different voltage dividing resistors have different corresponding measuring ranges. The meter head of the multimeter is a magnetoelectric system measurement device, which can only pass through direct current, and use diodes to change alternating current into direct current, thereby realizing the measurement of alternating current.
