Motion detector

A motion detector is an electronic sensor that detects movement in its surroundings and acts as a switch. There are different types, including PIR sensors, microwave and ultrasonic sensors. PIR sensors (pyroelectric infrared sensors) are the most common and respond to changes in temperature, such as when a person walks past. These sensors are often combined with a twilight switch to activate lighting only when it is dark. The settings include switch-on time, ambient brightness and detection range. Microwave motion detectors work optimally at changing distances and ultrasonic sensors are less common due to the complex technology involved. There are two-pole and three-pole motion detectors. Two-pole sensors do not require their own neutral conductor, but are only suitable for incandescent lamps. Three-pole motion detectors have their own neutral conductor connection and are more versatile. Presence detectors recognise even the smallest movements, ideal for quiet activities. They often have two switching channels to control lighting and other devices independently of each other. Specialised motion detectors are available for intruder alarm systems, which minimise false alarms by combining different sensors. Some models offer animal immunity and cover monitoring. Applications range from lighting control and intruder alarms to video surveillance and traffic control. PIR sensors are often used on traffic lights and motorways for traffic control.