A basic inductive speed sensor, also known as a magnetic speed sensor or an inductive proximity sensor, is a device used to detect the speed of rotating equipment. It operates on the principle of electromagnetic induction to sense the presence and frequency of a rotating target. Here's how it works:
Sensor Construction: The basic inductive speed sensor consists of a coil wound around a magnetic core. The coil is connected to an oscillator circuit.
Magnetic Field: When power is supplied to the sensor, the oscillator generates an alternating magnetic field around the coil.
Target Wheel: The rotating equipment that needs its speed measured is equipped with a target wheel or gear. This wheel or gear has specially designed teeth or slots that interrupt the magnetic field as they pass in front of the sensor.
Inductive Effect: As the teeth or slots on the target wheel move in front of the inductive sensor, they disturb the magnetic field. This disturbance induces voltage changes in the coil based on the speed and frequency of the interruptions.
Frequency Detection: The induced voltage changes result in a frequency output from the sensor. The frequency of the output signal is directly proportional to the speed of the rotating equipment.
Signal Processing: The output signal from the inductive sensor is then processed by a signal conditioning circuit or microcontroller to convert the frequency into speed units (e.g., revolutions per minute - RPM).
Speed Measurement: The processed speed information can be displayed on a screen, recorded for data logging purposes, or used for control and feedback systems.
Inductive speed sensors are commonly used in various applications such as automotive speedometers, industrial machinery, conveyor systems, and more. They are reliable, cost-effective, and provide accurate speed measurements for rotating equipment. However, they do have some limitations, such as the need for close proximity to the target and vulnerability to certain environmental factors like temperature and moisture. In specialized applications or under harsh conditions, other types of speed sensors like Hall effect sensors or optical encoders may be used instead.