How to use a clamp ammeter to measure AC current
The purpose, selection, and pre use inspection of clamp type ammeters
1. Purpose: It can measure AC current on low-voltage lines without interrupting load operation.
2. Selection: Its accuracy and maximum range should meet the needs of testing.
3. Pre use inspection:
(1) Appearance inspection: All parts should be intact and undamaged; The grip operation should be flexible; The clamp iron core should be rust free and tightly closed; The insulation sheath of the iron core should be intact; The pointer should be able to swing freely; The gear change should be flexible and have clear hand sensing;
(2) Adjustment: Place the table flat, with the pointer pointing to the zero position, otherwise adjust to the zero position.
measure
1. Select the appropriate gear. The principle of gear selection is:
(1) When the range of the measured current is known: choose the gear that is greater than the measured value but closest to it.
(2) When the range of the measured current is unknown: it can be tested at the highest current level first (or based on the wire cross-section, estimate its safe current carrying capacity, and select an appropriate gear), and decide whether to downshift the measurement according to the test results. In short, the deflection angle of the watch needle should be kept as large as possible.
2. The tester should wear gloves, flatten the watch, open the jaws, and allow the tested wire to enter the jaws before closing the jaws.
3. Reading: Take a reading on the corresponding scale line based on the gear used. (Attention! The gear value is the full offset value).
4. If the deflection angle of the watch needle is still very small when measured at the lowest gear (the small deflection angle of the watch needle means that the relative error of its measurement is large), it is allowed to wrap the wire several turns on the clamp iron core, close the clamp, and take the reading. At this point, the current value on the wire=reading ÷ number of turns (calculation of turns: how many wires are inside the clamp, even if it is a few turns).
Safety issues to be noted in measurement
1. Before measuring, thoroughly check the meter and select the correct gear.
2. Gloves (insulated gloves or clean and dry wire gloves) should be worn during testing, and guardianship should be set up if necessary.
When shifting gears for measurement, the wire should be removed from the jaws first, and then clamped in for measurement after shifting gears.
4. It is not possible to measure the current on bare conductors.
5. When measuring, pay attention to maintaining a safe distance from nearby charged objects. And attention should be paid not to cause phase to phase short circuits and phase to ground short circuits.
6. After use, the gear should be placed in the highest current range. If there is a watch cover, it should be placed in the cover and stored in a dry, dust-free, corrosion-free gas free, and vibration free place.
