How to use a clamp-on ammeter for AC current measurement
Clamp ammeter use, selection and pre-use inspection
1. Use: It can measure the AC current on the low-voltage line without interrupting the load operation.
2. Selection: Its accuracy and maximum range should meet the needs of the test.
3. Pre-use inspection:
(1) Appearance check: all parts should be intact; clamp handle operation should be flexible; jaw core should be free of rust, closure should be tight; core insulation sheath should be intact; the pointer should be able to swing freely; gear change should be flexible, hand sensing obvious;
(2) Adjustment: lay the table flat, the pointer should point at zero, otherwise adjust to zero.
Measurement
1. Select the appropriate gear. The principle of gear selection is:
(1) when the range of measured current is known: choose the gear that is larger than the measured value but closest to it.
(2) do not know the range of current being measured: can be placed in the first current of the highest level of test (or according to the cross-section of the wire, and estimate the safety of its current-carrying capacity, the appropriate selection of gears), according to the test situation to determine whether the need to downgrade the measurement. In short, the deflection angle of the needle should be as large as possible.
2. The test person should wear gloves, the flat end of the table, open the jaws, so that the measured wire into the jaws and then close the jaws.
3. Reading: According to the gear used, take the reading on the corresponding scale. (Note! Gear value is the full bias value).
4. If measured in the lowest gear, the needle deflection angle is still very small (needle deflection angle is small, meaning that the relative error of its measurement is large), allowing the wire in the jaws of the core winding a few turns, close the jaws and take a reading. The current value on the wire = reading ÷ number of turns (turns of the calculation: the inside of the jaws of a few lines, counted as a few turns).
Measurement should pay attention to the safety issues
1. Check the meter fully before measurement and select the gear correctly.
2. Test should wear gloves (insulated gloves or clean and dry gloves), if necessary, should be set up into the guardianship.
3. Need to change gear when measuring, should be the first wire from the jaws of the exit, change gear and then clamp into the wire measurement.
4. Can not measure the current on the bare conductor.
5. Measurement, pay attention to maintain a safe distance from the nearby charged body. And should be careful not to cause a short circuit between phases and relative to ground short circuit.
6. After use, it should be placed in the highest current level, and when there is a meter set, it should be placed in the meter set and stored in a dry, dust-free, non-corrosive gas and vibration-free place.
Current knowledge
1. The line current is equal to the phase current in the star connection circuit.
2. Triangular connection current line current is equal to times the phase current.
3. Calculate the rated current according to the power of the equipment P size; three-phase motor 1KW ≈ 2A single-phase electricity 1KW ≈ 4.5A
