ABSTRACT
This chapter introduces the most common current sensors. An isolated current sensor is free of any metallic connection to the circuit being measured. It is also essentially free of capacitive coupling so that it is safe to use with grounded amplifiers and other equipment. By far, the simplest current-to-voltage converter is the resistor. In current-measuring service, it is called a shunt even though it is typically placed in series with the load. Magnetic materials that are also electric conductors have free carriers, which are affected by alternating magnetic fields. As they move back and forth, they encounter electric resistance and dissipate energy in the form of heat. Galvanic isolation of current-measuring schemes becomes more and more important when there is no human observer looking at a meter that might be running at a high voltage. The current transformer remains a popular way to accomplish isolation for alternating current systems.
