Current sensors are devices used to measure the current in a circuit, and they can also be referred to as current sensors or current sensing transformers. They can be used to measure various types of AC and DC currents, including Hall effect, Roche coils, and transformers.Small current sensorThere is no direct electrical connection between the current being monitored, so the measurement circuit can be isolated by current.

Current sensors operate in open or closed-loop circuits. Open loop sensor circuits are usually cheaper than closed-loop alternatives, but have lower accuracy. Open loop sensors directly obtain current by detecting voltage. This may lead to errors caused by nonlinearity, saturation effects, and temperature drift in the sensor. A closed-loop sensor utilizes the detection voltage from the primary coil to provide reverse current to the secondary coil wound on the same iron core. Adjust the current through feedback loop to balance the magnetic flux generated by the primary circuit current. This balance eliminates the effects of temperature drift and saturation, and allows for more accurate measurements by monitoring the secondary current. The increased complexity leads to higher costs. Closed loop detectors are also known as zero flux sensors or zero detectors.

The Hall effect sensor detects the magnetic flux caused by the current in the measured conductor and generates current in the induction coil. The device is placed in the gap between the induction coil core and outputs a Hall voltage proportional to the coil current, with the following relationship:

Vh=Rh*（I/t*B）

Among them:

VH is the Hall voltage, measured in volts

RH is the Hall effect coefficient

I is the current through the sensor, measured in amperes

T is the thickness of the sensor, measured in millimeters

B is the magnetic flux density, measured in Tesla

The output signal of a linear (analog) sensor comes directly from the output of the operational amplifier connected to the sensor. The open-loop system uses Hall effect voltage output to directly measure current. The closed-loop system will convert Hall effect voltage into current, drive the secondary coil, and form magnetic flux balance, as mentioned earlier.

Around a spiral coil, around a special coil, around a coil, around a spiral coil. The induced voltage at both ends of the integrated wire is generated by current. They are a low-cost AC measurement method that can measure high-speed current pulses due to their low inductance. They can also measure high currents because there is no core, otherwise it would saturate. The integrator provides a special ADC to measure this value. Roche coil sensors are applied in high-performance welding systems, short-circuit testing, and high current measurement. Parallel resistors can be connected in series with a power source to induce current. The current flowing through the shunt will generate a voltage potential proportional to the product of the current and the shunt resistance. This can be tapped and measured by an analog-to-digital converter (ADC). Special precision, low impedance (mOhms) parallel resistors can be used for this function. Transformer current sensors (also known as current clamp instruments) are used to detect and measure alternating current. They are commonly used in applications such as testing equipment, where split ferrite or soft iron rings are wrapped around the conductor of the current being measured. The wire is wound around the core material to form a current transformer, with only one wire around it. They are very good for high currents, but not very good for measuring small AC currents.