Watersavers Supply a Range of PIR Motion Sensor Switches
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Passive InfraRed sensors (PIRs) or (PIR motion sensor) are electronic devices which are used in all types of gadgets to detect motion of an infrared emitting source, usually a human body.
How Do PIR Motion Sensors Work
The PIR motion sensor switch itself has two slots in it, each slot is made of a special material that is sensitive to Infrared (IR). The PIR switch is made up of two slots. When the PIR sensor is idle, both slots detect the same amount of Infrared, the ambient amount radiated from the room or walls or outdoors. When a warm body like a human or animal passes by, it first intercepts one half of the PIR motion sensor, which causes a positive differential change between the two halves. When the warm body leaves the sensing area, the reverse happens, whereby the PIR sensor generates a negative differential change. These change pulses are what is detected. PIR sensors are more complicated than many of the other sensors, there are multiple variables that affect the sensors input and output.
PIR Motion Sensors for Alarms
In the case of a security alarm, an intruder entering the protected area is detected when the infrared energy emitted from the intruder’s body is focused by a Fresnel lens or a mirror segment on the PIR switch and overlaps a section on the chip which had previously been looking at some much cooler part of the protected area. That portion of the chip is now much warmer than when the intruder wasn’t there. As the intruder moves, so does the hot spot on the surface of the chip of the PIR switch. This moving hot spot causes the electronics on the PIR sensor connected to the chip to de-energize the relay, operating its contacts, thereby activating the detection input on the alarm control panel of the PIR motion sensor.
PIR Motion Sensors to Save Energy and Water
A PIR sensor at Watersavers can be used for controlling water shut off valves, These PIR switches can control multiple solenoid shut off valves wired in parallel. Several PIR switches may be wired in parallel to cover larger areas if required. Watersavers supply a range of PIR switches to turn on water, lighting, heating, ventilation or air-conditioning loads when an area is occupied and switch off supplies when the area is vacated or unoccupied. PIR motion sensors can be fitted onto walls or ceilings and are used to save water and energy, ideal for high occupancy establishments such a schools or care homes, where if a tap is left on or vandalised, large amounts of water could be lost.
Overview of the PIR Switch
All objects, living or not, whose temperature is anything above absolute zero emit infrared radiation. This radiation (energy) is invisible to the human eye but can be detected by electronic devices designed for such a purpose.
The term ‘passive’ in this instance means the PIR switch does not emit any energy of any type but merely sits ‘passive’ accepting infrared energy through the ‘window’ in its housing.
PIR switches or PIR sensors as they are also known, allow you to sense motion, almost always used to detect whether a human has moved in or out of the PIR sensor’s range. They are small, inexpensive, low-power, easy to use and don’t wear out. For that reason they are commonly found in appliances and gadgets used in homes or businesses. They are often referred to as PIR motion sensors, “Passive Infrared”, Pyroelectric”, or “IR motion” sensors.
PIR sensors are basically made of a pyroelectric sensor, a round metal can with a rectangular crystal in the center which can detect levels of infrared radiation. Everything emits some low level radiation, and the hotter something is, the more radiation is emitted, the easier it is for a PIR sensor to detect.