The working principle and usage precautions of clamp ammeters
A clamp type ammeter is made based on the principle of a current transformer, and its appearance is like a clamp. When the wrench of the clamp type ammeter is tightly held, the iron core of the current transformer can be opened, and the wire of the measured current enters the clamp as the primary winding of the current transformer. When the wrench is relaxed and the iron core is closed, an induced current is generated on the secondary winding according to the principle of the current transformer, and the ammeter pointer deflects to indicate the measured current value.
The correct use and precautions of clamp ammeters
(1) Clamp type ammeters generally use a conversion switch to change the current limit, which has four levels: 5A, 1OA, 50A, and 250A; There are two voltage limits: 300V and 600V. When the measured current is less than 5A, in order to obtain a more accurate reading, if conditions permit, the wire can be wound a few more times and placed in the clamp for measurement. The actual current value is the instrument reading divided by the number of wires placed in the clamp.
(2) When measuring AC current, place the measuring wire in the middle of the clamp and tightly close the clamp.
(3) The clamp ammeter should be stored in a dry room and wiped clean before use.
(4) Two people should perform the measurement, one person for measurement and one person for supervision.
(5) The voltage of the tested circuit should not exceed the specified value indicated on the clamp ammeter, otherwise due to insufficient insulation strength of the meter, it is easy to cause grounding accidents or electric shock hazards.
(6) When measuring, wear insulated gloves, stand on an insulated mat, and do not touch other equipment to prevent short circuits or grounding. Observe the timing of the watch and pay attention to maintaining a safe distance between the head and the live parts.
(7) Do not switch the current limit switch during the current measurement process to avoid damaging the instrument; If necessary, the clamp ammeter should be removed from the wire for testing.
(8) Only one wire can be clamped in each measurement, and two or three wires cannot be clamped in simultaneously.
