What is a Current Clamp?

Clamp type ammeter is a kind of ammeter, used to measure the current value in the circuit, referred to as current clamp. In electrical and electronic engineering, current clamps (or current probes) are two clampable probes that can be opened to clamp electrical conductors around electrical equipment, and the probes do not need to contact the conductive parts of the equipment, that is, they do not need to be disconnected Device wires are used for probe insertion to measure the properties of the current in the conductor. Current clamps are commonly used to measure sine wave currents (alternating current (AC)). With more advanced detection instruments, phase and waveform can also be tested. Generally speaking, very high AC current (above 1000A) is easy to measure, while DC current and very low AC current (milliamp level) are difficult to measure accurate values.

The clamp current is a very common measuring instrument. The technology is more and more mature and the accuracy is getting higher and higher. From simple AC to current AC and DC, from analog to digital. The basic principle of a clamp ammeter is equivalent to a current transformer, and the measured wire passing through the jaw is equivalent to the primary side of the transformer. When there is current on the primary side, the secondary side will induce a voltage and generate a current. Then add a variety of current measurement circuits to form a clamp ammeter. The biggest advantage of clamp current is that it is a hand-held instrument without wiring, online detection, and convenient measurement. It is widely used in power, energy, transportation, elevator and other industries.

Normally used

(1) The clamp ammeter has a wide range, from a few amps to several thousand amps, and an appropriate range should be selected. You cannot use a small range to measure a large current, otherwise the meter will burn out, and you cannot use a large number of programs to measure a small current, otherwise a large measurement error will occur.

(2) Is the function of the clamp ammeter purely AC or AC and DC? Does it have other functions, such as voltage, resistance, and low current functions? Can it meet our needs.

(3) Whether the accuracy of the clamp ammeter can meet the needs of our current measurement accuracy.

(4) The rated voltage of the clamp ammeter is higher than the voltage of the line we need to measure.

(5) The clamp jaw size of the clamp ammeter. If a thick wire is measured, the clamp ammeter should be larger. ^[1]

Because clamp ammeters are devices that measure large currents, we need to consider both accuracy and safety. You should always check more and find out

Digital clamp ammeter is mainly composed of transformer-type clamp or Hall-type clamp (including fixed jaw, movable jaw and Hall magnetic sensor), jaw trigger, function range selection switch, measurement circuit and digital voltage. Table (DVM) and other components.

(1) Transformer-type clamp head: Its structure, principle, and function are the same as those of the pointer-type clamp ammeter. See the previous chapter for related content. This clamp can only detect AC current.

(2) Hall-type clamp head: The clamp-type magnetic core is made into a tensioned structure, and the Hall magnetic sensor (based on the Hall effect as its working basis can detect the magnetic field and its changes) is placed on the clamp-type cold-rolled silicon steel sheet In the gap, the clamp core is clamped outside the conductor through which the measured current flows. When a current flows through the conductor, a magnetic field is generated in the clamp core. Its magnitude is proportional to the number of ampere turns of the current flowing through the wire. This magnetic field acts on the Hall element and induces the corresponding Hall potential to measure the current flowing in it. This clamp can both detect AC current. DC current can also be detected.

(3) Measurement circuit: It includes various function converters, and its task is to convert various electrical parameters to be measured into tiny DC voltage signals that can be accepted by digital voltage basic meters. ^[2]