The Principle of Current Measurement with Clamp Meters and Current Clamps
In daily work, for most engineers, multimeters are used to measure electrical signals such as voltage, low current, and resistance. However, when testing high currents, clamp ammeters are generally preferred. The clamp gauge is as important a tool as a multimeter in the minds of engineers.
Principle of clamp ammeter
Clamp gauges can be divided into single AC clamp gauges and AC/DC clamp gauges, and their principles are different.
Single cross current clamp: The clamp head adopts an electromagnetic current transformer. Through a coil with a certain turns ratio, AC electricity can generate electromagnetic induction in the clamp head coil, obtaining a current proportional to AC electricity. Then, through conversion, the electrical signal is converted into a digital signal.
AC/DC clamp meter: The clamp head adopts Hall active current clamp. Active components can not only induce electromagnetic fields of alternating current, but also convert magnetic field signals into electrical signals, outputting a voltage signal proportional to the measured current. By relying on Hall elements for measurement and amplification, direct current signals can be tested.
As is well known, a multimeter can only measure small currents (usually within 10A, and 20A can last for several seconds), and it is necessary to disconnect the tested circuit and connect the multimeter in series to the circuit. There is no clamp meter to measure current conveniently and efficiently. Many industrial sites use a combination of current clamps and multimeters to test high currents, maximizing the value of the multimeter.
When using a single AC clamp meter, AC/DC clamp meter, and multimeter in combination, there are differences in operation
Precautions for using a combination of a single AC clamp meter and a multimeter: As the output signal of a single AC clamp meter is generally converted from mA to A, it is necessary to set the multimeter to the milliampere mA position.
Precautions for the combination of AC/DC clamp meter and multimeter: The output signal of the AC/DC clamp meter is generally converted from mV to A, so it is necessary to set the multimeter to the mV position.
