A basic inductive speed sensor, also known as a proximity sensor or an inductive proximity sensor, is a type of sensor used to detect the speed of rotating equipment. It operates on the principle of electromagnetic induction and is commonly employed in various industrial applications, such as monitoring the speed of motors, conveyor belts, and other rotating machinery. Here's how it works:
Inductive Principle: The sensor generates an electromagnetic field around its active sensing face. When a conductive target, such as a metal gear tooth or a ferrous metal part, enters this electromagnetic field, it induces eddy currents in the target. These eddy currents, in turn, create their own magnetic field, opposing the original field generated by the sensor.
Change in Inductance: As the target rotates, its presence causes fluctuations in the magnetic field and induces changes in the sensor's inductance. The rate of these changes corresponds to the speed of the rotating equipment.
Detection Circuitry: The inductive sensor is connected to electronic detection circuitry that monitors the inductance changes caused by the rotating target. The circuitry converts these changes into electrical signals, typically pulses, which are proportional to the speed of the rotating equipment.
Signal Processing: The electrical pulses generated by the sensor can be further processed by other electronic components or microcontrollers to derive the actual speed value. Depending on the application, additional circuitry may be used to count the pulses over a specific time interval to calculate the rotational speed in rotations per minute (RPM) or revolutions per second (RPS).
Output: The speed information can be used for various purposes, such as speed control, safety monitoring, or data logging.
Inductive speed sensors are popular in industrial settings due to their simplicity, durability, and resistance to environmental factors such as dust, dirt, and moisture. However, they are primarily suited for detecting metallic targets at relatively short sensing distances, typically a few millimeters to a few centimeters. If non-metallic targets or longer sensing distances are required, alternative sensor technologies like optical encoders or hall effect sensors may be more suitable.