How to use clamp ammeter and precautions

       Clamp-type ammeter (referred to as clamp meter) is a meter that integrates current transformer and ammeter. Its working principle is the same as that of current measurement by current transformer. The clamp meter is a combination of a current transformer and an ammeter. The core of the current transformer can be opened when the wrench is tightened, and the wire through which the current is measured can pass through the open gap of the core without cutting. When the wrench is released, the core is closed. The wire of the circuit under test that passes through the core becomes the primary coil of the current transformer, and the current is induced in the secondary coil by passing the current. Therefore, the ammeter connected to the secondary coil has an indication-the current of the circuit under test is measured.
　　Clamp-type ammeters are divided into high and low voltage, which are used to directly measure the current in the line without disconnecting the line. It is used as follows:
　　1. When using a high-voltage clamp meter, pay attention to the voltage level of the clamp-type ammeter. It is strictly prohibited to use a low-voltage clamp meter to measure the current of the high-voltage circuit. When measuring with a high-voltage clamp meter, it should be operated by two people. Non-duty personnel should also fill in the second type of work ticket. During the measurement, they should wear insulating gloves and stand on insulating mats. They must not touch other equipment to prevent short circuits or grounding. 2. When one phase of the cable is grounded, measurement is strictly prohibited. Prevent the danger of personal safety caused by the low level of insulation of the cable head due to the breakdown of the ground. 3. After the clamp ammeter measurement is completed, pull the switch to the maximum range to avoid accidental overcurrent when it is used next time; and it should be stored in a dry room. 4. Watch the meter, pay special attention to maintaining a safe distance between the head and the charged part. The distance between any part of the human body and the charged body must not be less than the entire length of the clamp meter. 5. When measuring on a high-voltage circuit, it is forbidden to use a wire to measure from another 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 should be more than 300mm, and the insulation should be good. Only when the measurement is considered convenient, can it be performed. 6. When measuring low-voltage fusible fuses or horizontally arranged low-voltage bus currents, each phase of the fusible fuse or the bus should be protected and insulated with insulating materials before measurement to avoid short-circuits between phases.