FAQ | Feb 18,2023
The “direct” measurement method of current sensors works without any additional logic circuits. The more common method in this sensor measurement is to use a shunt resistor and then connect it to the circuit under test in series.
Shunt resistors are very low resistors precisely predetermined by the manufacturer. A shunt resistor works by connecting it to a circuit in series and measuring the voltage across the resistor as a current flows through it. According to Ohm’s law, the voltage is proportional to the current flowing because we know the exact resistance of the shunt. Choosing a shunt with high accuracy is critical because it will actually define the accuracy of the measurement itself.
Using this method, you can measure AC or DC, but there are some considerations. First, the stated current of the shunt should not be exceeded, as this may burn out the resistor. Second, if the maximum declared current flows through the shunt for a long period of time, the shunt will heat up and eventually overheat. The shunt resistance varies with temperature and can change permanently if the shunt overheats. As a result, diverters typically use only about 60% of their stated current level.
Sometimes it is not possible to interrupt the conductor to connect the adapter for the current we wish to measure. Flow current can also be measured with current sensors. This is possible because the flowing current creates a magnetic field around the conductor, and current sensors measure the strength of the magnetic field around the conductor in a number of different ways, and current sensors are also current-isolated.
A quick overview of sensors and how they measure current through magnetic fields. These types of sensors are isolated from conductors, which means easier, faster, and safer measurements. This type of measurement is safer for both measuring instruments because current isolation eliminates the possibility of high common-mode voltages when using shunt resistors to measure high voltage currents.
We must keep in mind that these types of sensors have a phase shift to the output voltage compared to the measured current. The degree of phase shift depends on the type of current sensor and the frequency measured. Using high-precision current sensors, the phase shift is almost zero; With cheaper sensors, the phase shift may exceed 10° at the fundamental frequency and even more at higher
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