How to measure AC current using a clamp ammeter
The purpose, selection and pre-use inspection of clamp ammeter
1. Purpose: It can measure the AC current on low-voltage lines without interrupting load operation.
2. Selection: Its accuracy and maximum range should meet the needs of the test.
3. Check before use:
(1) Appearance inspection: All parts should be intact; the operation of the pliers should be flexible; the core of the jaws should be rust-free and tightly closed; the core insulation sheath should be intact; the pointer should be able to swing freely; the gear change should be flexible and hand-sensitive. obvious;
(2) Adjustment: Place the watch flat, and the pointer should point at the zero position, otherwise adjust it to the zero position.
Measurement
1. Select the appropriate gear. The principles for file selection are:
(1) When the measured current range is known: select the range that is larger than the measured value but closest to it.
(2) When the range of the current to be measured is not known: you can first test the highest current level (or select the appropriate gear according to the cross section of the conductor and estimate its safe current carrying capacity), and decide whether to downgrade the measurement based on the test conditions. In short, the deflection angle of the watch hand should be as large as possible.
2. The tester should wear gloves, hold the flat end of the meter, open the jaws, let the wire under test enter the jaws, and then close the jaws.
3. Reading: According to the gear used, read the reading on the corresponding scale line. (Note! The gear value is the full offset value).
4. If measuring at the lowest gear, the deflection angle of the meter needle is still very small (the deflection angle of the meter needle is small, which means that the relative error of the measurement is large), it is allowed to wind the wire around the jaw core for a few turns, and after closing the jaws Take readings. At this time, the current value on the wire = reading ÷ number of turns (calculation of the number of turns: the number of wires inside the jaw is counted as the number of turns).
Safety issues that should be paid attention to during measurement
1. Fully check the meter before measuring and select the gear correctly.
2. Gloves (insulating gloves or clean and dry wire gloves) should be worn during testing, and a monitor should be installed if necessary.
3． When it is necessary to change gears for measurement, the wire should be withdrawn from the jaws first, and then clamped in for measurement after changing gears.
4. Current on bare conductors cannot be measured.
5. When measuring, be sure to keep a safe distance from nearby charged objects. And care should be taken not to cause phase-to-phase short circuit and phase-to-ground short circuit.
6. After use, the gear should be set to the highest current level. If there is a watch case, put it into the watch case and store it in a dry, dust-free, corrosive gas-free and vibration-free place.
