A basic inductive speed sensor, also known as an inductive proximity sensor or proximity switch, is a type of sensor used to detect the speed of rotating equipment. It operates on the principle of electromagnetic induction and is commonly used in industrial applications for monitoring and controlling rotating machinery. Here's how it works:
Inductive Principle: The sensor consists of a coil of wire that is wound around a core. When alternating current (AC) flows through this coil, it generates an electromagnetic field around the sensor.
Target Object: The rotating equipment (e.g., a gear, shaft, or wheel) needs to have a metal component for the inductive speed sensor to work effectively. As the metal component rotates, it interacts with the sensor's electromagnetic field.
Eddy Currents: As the metal target moves through the electromagnetic field, it induces eddy currents in the metal. Eddy currents are circular currents that flow within the metal and create their own magnetic fields.
Induced Voltage: The presence of eddy currents in the metal target causes a change in the sensor's electromagnetic field. This change induces a voltage in the coil of the sensor.
Frequency Detection: The speed of the rotating equipment is directly proportional to the frequency of the induced voltage in the coil. The higher the rotational speed, the higher the frequency of the induced voltage.
Signal Processing: The induced voltage signal is then processed by electronic circuitry within the inductive speed sensor to provide a usable output. This output can be a digital signal or an analog signal, depending on the specific sensor's design.
Speed Measurement: The frequency of the induced voltage is converted into a speed measurement, allowing the sensor to determine the rotational speed of the target object.
The inductive speed sensor can provide a real-time measurement of the speed of rotating equipment, making it valuable for various applications, such as monitoring conveyor belt speeds, motor RPMs, and other industrial processes. It is commonly used due to its non-contact nature, robustness, and ability to function in harsh environments where other types of sensors might be unsuitable.