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. The sensor is non-contact and works by detecting changes in magnetic fields caused by the moving target, such as a gear, shaft, or any other metallic object.
Here's how it typically works:
Sensor Construction: The inductive speed sensor consists of a coil of wire wound around a ferromagnetic core. This coil generates an electromagnetic field when an alternating current (AC) is passed through it.
Moving Target: The target equipment, which may be a gear, shaft, or any metallic object, needs to have some ferromagnetic properties or be made of a material that can interact with the magnetic field.
Magnetic Interaction: As the target equipment rotates, it passes by the inductive speed sensor, causing changes in the magnetic field around the sensor. When the metal target approaches the sensor, it causes an increase in the magnetic flux passing through the sensor's coil. When the target moves away from the sensor, the magnetic flux decreases.
Induced Voltage: The changing magnetic field induces a voltage in the coil of the sensor, which generates an alternating current (AC) signal.
Signal Processing: The induced AC signal is then processed by the sensor's electronics to determine the speed of the rotating equipment. The sensor electronics may include a signal conditioner or a frequency-to-voltage converter to convert the AC signal into a more usable form.
Output: The output of the inductive speed sensor is typically a voltage, frequency, or pulse signal that corresponds to the speed of the rotating equipment.
Advantages of inductive speed sensors include their non-contact operation, which means they do not physically touch the moving parts, leading to minimal wear and tear and reduced maintenance requirements. Additionally, they can work in harsh environments with dirt, dust, and other contaminants. However, it's essential to ensure that the sensor is appropriately positioned and adjusted to achieve accurate speed measurements.