A basic inductive speed sensor, also known as a proximity sensor or an inductive proximity sensor, is a type of non-contact sensor used to detect the speed of rotating equipment. It operates on the principle of electromagnetic induction and is commonly used in industrial applications to monitor the rotational speed of machines, motors, and other rotating equipment.
Here's how a basic inductive speed sensor works:
Principle of Induction: The sensor contains a coil of wire that is energized with an alternating current (AC). When AC current flows through the coil, it generates a magnetic field around it.
Target Object: The rotating equipment to be monitored must have a metallic target (such as a gear tooth, a bolt head, or a metal disk) attached to its rotating shaft. This target object should be made of a conductive material (e.g., steel) to interact with the sensor's magnetic field.
Magnetic Field Interaction: As the metallic target on the rotating equipment passes near the sensor, it enters the magnetic field generated by the coil. This interaction induces eddy currents in the target metal.
Change in Inductance: The presence of eddy currents in the metallic target causes a change in the inductance of the sensor's coil. The rate at which the inductance changes is directly proportional to the speed at which the target rotates. As the target moves faster, the rate of change in inductance increases.
Signal Output: The sensor's circuitry detects the change in inductance and converts it into an electrical signal, typically a voltage or a frequency signal. The frequency or voltage output corresponds to the speed of the rotating equipment.
Signal Processing: In many cases, the output signal from the inductive speed sensor is processed further by a control system or a microcontroller to display, record, or control the equipment's speed as required for the specific application.
It's important to note that inductive speed sensors require metallic targets to operate effectively, and the distance between the sensor and the target must be within the sensor's specified sensing range for accurate speed detection. Also, the speed range and resolution of the sensor depend on its design and application-specific requirements. Inductive speed sensors are widely used due to their robustness, non-contact operation, and ability to work in harsh environments with dust, dirt, and moisture. However, they may not be suitable for all types of materials or speed ranges, as some materials may not interact strongly with the magnetic field, leading to decreased sensitivity or accuracy.