Current sensing devices
– Current sensor
– Detects electric current in a wire
– Generates a signal proportional to the current
– Signal can be analog voltage, analog current, or digital output
– Types of current sensors
– Alternating current input
– Analog output
– Bipolar output
– Unipolar output
– Hall effect sensor
– Transformer or current clamp meter
– Fluxgate sensor
– Shunt resistor
– Fiber optic current sensor
– Rogowski coil
– Giant Magnetoresistance (GMR) sensor
Shunt resistors for current sensing
– Ohm’s Law and shunt resistors
– Voltage drop across a resistor is proportional to the current
– Shunt resistor as a common approach to current sensing
– Voltage drop across the shunt is proportional to the current flow
– Advantages of shunt resistors
– Can measure both AC and DC currents
– Low-cost surface mounted devices (SMDs) preferred for small size and low prices
Current sensing using trace resistance
– Using intrinsic resistance of a conducting element (e.g., copper trace)
– No additional resistor required, resulting in a low-cost and space-saving configuration
– Challenges with trace resistance sensing
– Very low voltage drop, requiring a high gain amplifier for a useful signal
– Thermal drift and initial conditions affecting measurement accuracy
– Use of digital controllers for thermal drift compensation and calibration
Current sensing based on Faraday’s Law
– Faraday’s Law of induction in current sensing
– Current transformers (CTs) and Rogowski coils as major sensing devices
– Intrinsic electrical isolation between the current to be measured and the output signal
– CTs convert high primary current into smaller secondary current using a transformer principle
– Rogowski coils integrate the current to be measured based on Faraday’s Law of induction
Magnetic field sensors for current sensing
– Hall effect sensors
– Activated by an external magnetic field
– Senses the magnetic field produced by the magnetic system
– Provides electrical isolation between the current to be measured and the output signal
– Fluxgate sensors
– Work on the same measurement principle as Hall-effect-based current sensors
– Use saturable inductor instead of Hall-effect sensor in the air gap
– Advantages include high resolution, accuracy, low offset and gain drift, and large bandwidth
– Magneto-resistive current sensor
– Two-terminal device that changes its resistance with applied magnetic field
– Popular types include AMR, GMR, GMI, and TMR
– Higher sensitivity compared to Hall-effect sensors
Note: The content also includes a subtopic on Hall sensors, a brief mention of current sensing monitors, and a “See also” section that is not included in the grouping. Source: https://en.wikipedia.org/wiki/Current_sensing_techniques
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.
