How is a clamp ammeter a measuring instrument
A clamp type ammeter consists of a current transformer and an ammeter. It is an instrument used to measure the current level of an operating electrical circuit, and can measure AC current without interruption.
Clamp type ammeters are mainly used to measure the magnitude of current in running electrical circuits (some clamp type ammeters can also measure voltage). Below, we will take clamp type ammeters as an example to understand the usage method of clamp type ammeters.
When measuring current with a clamp type ammeter, clamp the running wire to be tested into the iron core window of the clamp type ammeter, and then read the reading of the pointer on the meter head. When measuring for the first time, estimate the maximum current level first, and then shift to the appropriate range for formal measurement readings. During each range change, the jaws must be opened and the range switch must be switched. The jaws of the clamp type ammeter must be kept clean and dry.
If a small current is measured using the minimum current gear and the pointer deflection is less than 1/2 of the range, making it difficult to read, the wire to be measured can be wound a few turns in the clamp, and the reading can be divided by the number of turns of the wire to be wound to obtain the current value to be measured.
When the wire is clamped into the clamp, if vibration or impact sound is found on the clamp ammeter, the handle of the clamp ammeter should be turned a few times or the clamp should be reopened and closed once until there is no noise before reading the current value.
Note that the voltage of the circuit to be tested should not be higher than the rated voltage of the clamp ammeter, and be careful during operation.
The principle of clamp ammeter
The iron core of the transformer is made into a movable opening and formed into a clamp shape. The movable part is connected to the handle 6. When the handle is tightly grasped, the iron core of the current transformer opens, and the tested wire 4 can be placed in the clamp. The current carrying wire becomes the primary winding of the current transformer, and the clamp is closed. Alternating magnetic flux passes through the iron core of the current transformer, and induced current is generated in the secondary winding 5 of the transformer. The ammeter is connected to both ends of the secondary winding, The current indicated by its pointer is directly proportional to the working current of the clamped current carrying wire, and the measured current value can be directly read from the dial. The clamp current meter is essentially composed of a current transformer, clamp wrench, and a rectifier magnetoelectric reaction force instrument.
