Advantages of PIR sensor | disadvantages of PIR sensor

This page covers advantages and disadvantages of PIR sensor (Passive Infrared Sensor) including its working. It mentions PIR sensor advantages or benefits and PIR sensor disadvantages or drawbacks.

What is PIR sensor ? | Passive Infrared Sensor

PIR sensor is used as occupancy sensor. PIR sensor is passive sensor as it senses infrared signal emitted by various objects including human body. They are used as alternative to microwave sensors.

PIR sensor houses pyro-electric sensor as shown in the figure-2. PIR sensor generates energy when exposed to heat. Human or animal body radiates energy in the form of infrared radiation. Hence when human/animal come in the range of PIR motion sensor, it receives thermal energy and hence motion is detected by the sensor.

Benefits or advantages of PIR sensor

Following are the benefits or advantages of PIR sensor:
➨Detects motion reliably in indoors as well as in day or dark.
➨It consumes less energy (0.8W to 1.0W) compare to microwave sensor.
➨They are cheaper compare to microwave sensors.
➨They are good for electrical applications used in smaller and compact premises.

Drawbacks or disadvantages of PIR sensor

Following are the drawbacks or disadvantages of PIR sensor:
➨They have lower sensitivity and less coverage compare to microwave sensors.
➨It does not operate greater than 35 degree C.
➨It works effectively in LOS (Line of Sight) and will have problems in the corner regions.
➨It is insensitive to very slow motion of the objects.
➨Since PIR sensors sense heat signatures in room, they are not very sensitive if the room itself is warm. Hence PIR sensors are not able to detect human beings in the summer in some countries like INDIA.
➨Snoozing is another problem with PIR sensors. PIR sensors may turn off even if there is very little movement in occupied floors.
➨Thieves may find it easy to fool PIR detection range as they have slotted detection zone and not continuous one like microwave sensor.

Also refer advantages and disadvantages of motion sensor >> and difference between active motion sensor and passive motion sensor >>.

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