Correct use of clamp ammeter to measure AC current
Application, selection and inspection before use of clamp ammeter
1. Purpose: It can measure the AC current on the low-voltage line without interrupting the load operation (without disconnecting the current-carrying wire). (Below 50HZ 500V)
2. Type selection: its accuracy and maximum range should meet the needs of the test.
3. Check before use:
(1) Appearance inspection: all parts should be in good condition; the clamping handle should be flexible; the iron core of the jaws should be free from corrosion and tightly closed; the insulation sheath of the iron core should be intact; the pointer should be able to swing freely; ;
(2) Adjustment: put the meter flat, the pointer should point to zero, otherwise adjust to zero.
Measurement
1. Select the appropriate gear. The principle of gear selection is:
(1) When the measured current range is known: select a gear that is larger than but close to the measured value.
(2) When the current range to be measured is unknown: it can be placed in the current test first (or according to the cross section of the wire, and its safe current carrying capacity is estimated, appropriately selected), and whether downshift measurement Whether it needs to be determined according to the test situation. In short, the deflection angle of the hand should be as large as possible.
2. The tester should wear gloves, flatten the end of the instrument, open the jaws, and close the jaws after the wire under test enters the jaws.
3. The wire to be tested should be located in the center of the jaw space, and the jaws should be tightly closed;
4. After measuring a large current, before measuring a small current, the jaws should be opened and closed several times to demagnetize;
5. When measuring small currents, if the deflection angle of the needle is still small when measuring the gear (the deflection angle of the needle is small, which means that the relative error of its measurement is large), it is allowed to wind the wire on the jaw iron core Go around a few times and take a reading after closing the jaws. At this time, the current value on the wire = reading ÷ the number of turns (the calculation of the number of turns: how many wires are in the jaw, calculated by how many turns);
6. Reading: According to the gear used, read the reading on the corresponding scale line. (Note! The gear value is the full offset value);
7. After use, the gear should be set to current.
