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Current Sensors

Current Sensors

What's the Current Sensors?

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.
  • 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

Requirements in current measurement

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

Techniques

  • 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.
    • Transformer or current clamp meter, (suitable for AC current only).
    • Fluxgate sensor, (suitable for AC or DC current).
    • Shunt resistor, whose voltage is directly proportional to the current through it.
    • Fiber optic current sensor, using an interferometer to measure the phase change in the light produced by a magnetic field.
    • Rogowski coil, electrical device for measuring alternating current (AC) or high speed current pulses.
    • Giant Magnetoresistance(GMR): Magnetic field sensor suitable for AC & DC Current with higher accuracy than Hall Effect. Placed parallel to the magnetic field.

    The Hall Effect current sensor is a type of current sensor which is based on the Hall Effect phenomenon discovered by Edwin Hall in 1879. Hall Effect current sensors can measure AC, DC, or pulsating current.