What is a motion sensor of flood light, high bay light?
Motion sensor lighting detects human movement over large areas using a variety of different technologies. They used to predominantly be utilised in burglar alarms and other security systems. But now it is more widely used to reduce unnecessary energy consumption by turning off the lights when there are no moving objects such as people and cars. When you get home late at night, the LED flood light in the front door will automatically light up.Infrared light isn’t visible to humans, but we perceive it as heat. All objects you can think of, including living beings, emit IR radiation. Our bodies have a skin temperature of about 34 degrees C (or 93 degrees F). This means we radiate infrared energy at a wavelength of 9 to 10 micrometers.
PIR sensors have no radiation, good concealment, and low power consumption, but their signal amplitude is easily affected by various heat sources and light sources.
Many types of motion sensor lighting use more than one technology to improve accuracy and reduce false alarms. For instance, it’s quite common to combine PIR and microwave technology in one system.
Both sensors need to trip for the system to activate. In the example above, that means the PIR sensor must detect a temperature change and the microwave sensor must sense a disturbance in the radiation waves. That means a rapid change in temperature won’t trigger the lights if it doesn’t detect any motion. Likewise, an object falling also won’t trigger the system without the required heat.
It’s pretty useful in providing more accurate lighting. There’s no wasted energy.
A downside to it, however, is if one learns how to avoid triggering one, the lights won’t turn on even if the other sensor detects motion. For this reason, some people use two types of technology separately, instead. You can, for example, equip your house with both a PIR sensor and a microwave one. However, this is more useful for security systems.