The clamp ammeter is an instrument that integrates the current transformer with the ammeter. Its working principle is the same as the current measurement principle of current transformer. The clamp meter is a combination of a current transformer and a current meter. After tightening the wrench, the core of the current transformer can be opened, and the wire to measure the current can pass through the opening gap of the core without being cut off. When the wrench is released, the core closes. The conductor of the circuit under test through the core wire becomes the primary coil of the ct, and the current is induced in the secondary coil through the current. Thus, an ammeter connected to a secondary coil has an indicator - to measure the current in the circuit under test.

The clamp ammeter is divided into high voltage and low voltage and is used to directly measure the current in the line without breaking the line. It is used as follows:

1. When using a high voltage clamp ammeter, please note the voltage level of the clamp ammeter. It is strictly forbidden to use the low-voltage clamp meter to measure the current in the high-voltage circuit. When using a high pressure clamp meter for measurement, two people should operate it. Non-duty personnel should also fill in the second type of work ticket. They should wear insulating gloves and stand on an insulating mat during the measurement. They must not touch other equipment to prevent short-circuiting or grounding.

2. When the cables are connected to the ground, it is strictly prohibited to measure, so as to avoid the danger of personal safety caused by the low insulation level of the cable head caused by the ground fault.

3. After the measurement of the clamp ammeter is completed, pull the switch to the maximum range so as to avoid accidental overcurrent in the next use. And should be stored in a dry room.

4. Observe the electricity meter and pay special attention to maintain a safe distance between the head of the machine and the charged part. The distance between any part of the body and the charged body shall not be less than the entire length of the clamp gauge.

5. When making measurements on the high voltage circuit, do not use wires to make measurements from the other meter of the clamp ammeter. When measuring the current of each phase of the high-voltage cable, the distance between the cable head and the wire shall be more than 300mm, and the insulation shall be good. Only when the measurement is considered convenient can it be performed.

6. When measuring the current of the low-voltage fuse or the horizontally arranged low-voltage bus, each phase of the fuse or bus shall be protected and insulated with insulating material before measurement, so as to avoid short circuit between phases.