Current sensing

In electrical engineering, current sensing is any one of several techniques used to measure electric current. The measurement of current ranges from picoamps to tens of thousands of amperes. The selection of a current sensing method depends on requirements such as magnitude, accuracy, bandwidth, robustness, cost, isolation or size. The current value may be directly displayed by an instrument, or converted to digital form for use by a monitoring or control system. Current sensing techniques include shunt resistor, current transformers and Rogowski coils, magnetic-field based transducers and others. A current sensor is a device that detects electric current in a wire and generates a signal proportional to that current. The generated signal could be analog voltage or current or a digital output. The generated signal can be then used to display the measured current in an ammeter, or can be stored for further analysis in a data acquisition system, or can be used for the purpose of control. The sensed current and the output signal can be: Alternating current input, analog output, which duplicates the wave shape of the sensed current. bipolar output, which duplicates the wave shape of the sensed current. unipolar output, which is proportional to the average or RMS value of the sensed current. Direct current input, unipolar, with a unipolar output, which duplicates the wave shape of the sensed current digital output, which switches when the sensed current exceeds a certain threshold Current sensing technologies must fulfill various requirements, for various applications. Generally, the common requirements are: High sensitivity High accuracy and linearity Wide bandwidth DC and AC measurement Low temperature drift Interference rejection IC packaging Low power consumption Low price The measurement of the electric current can be classified depending upon the underlying fundamental physical principles such as, Faraday's Law of Induction Magnetic field sensors Faraday Effect Hall effect sensor.