Analyzing the working principle of clamp Ammeter from its internal structure
The clamp meter is mainly composed of an electromagnetic Ammeter and a through core current transformer. The secondary winding of the through core current transformer is wound on the iron core and connected with the AC Ammeter. Its primary winding is the measured conductor passing through the center of the transformer. When measuring the current, press the wrench, open the jaw, and place the measured current carrying conductor in the middle of the through core current transformer. When there is alternating current in the measured conductor, the magnetic flux of the alternating current induces the current in the secondary winding of the transformer. This current passes through the coil of the electromagnetic Ammeter, causing the pointer to deflect, and indicating the measured current value on the dial scale. The clamp Ammeter must be connected in series with the circuit under test.
In actual operation, it is obviously inconvenient to disconnect the circuit. The clamp Ammeter is a portable instrument that can directly measure the AC current of the circuit without disconnecting the circuit. It is very convenient to use in electrical maintenance and is widely used.
The clamp type meter knob is actually a range selection switch, and the function of the wrench is to open and close the movable part of the core of the through core transformer, so as to clamp it onto the measured wire.
Precautions for use of clamp Ammeter are as follows:
(1) Before measuring with clamp type meter, set the Ammeter to zero. Check the opening and closing of the jaws, and ensure that the movable parts of the jaws open and close freely, and that the joint surfaces of the jaws on both sides are in close contact. When measuring, it is important to ensure that the jaws are tightly engaged to reduce magnetic flux leakage and improve measurement accuracy. Clamp type gauges
(2) When measuring, the measured wire should be placed in the center position of the clamp to reduce measurement error. The range selection knob should be placed in an appropriate position to make the pointer exceed the middle scale during measurement to reduce measurement error. If the current of the measured circuit is not known beforehand, the range selection knob can be placed in the high gear first, and then adjusted to the appropriate position based on the pointer deflection.
(3) When the current of the circuit being tested is too small, even when the deviation angle of the pointer is not large in the low range range range, in order to improve measurement accuracy, the current carrying wire being measured can be wrapped around the iron core column of the clamp part for several turns before measurement. The actual measured current value is obtained by dividing the number of wires inserted into the clamp by the number of wires indicated by the pointer.
(4) When the clamp type meter is not in use, the range selection knob should be turned to the high range position to avoid accidentally damaging the instrument in the next use. If there are oil stains and debris on the jaws, they should be cleaned with solvent; If there are rust spots, they should be gently wiped off
