What is the difference is between Presence and Absence detection?
Presence detectors
Presence detectors sense moving infra red heat and then switch on their loads starting a timer. When there is no movement in the area the time elapses and the unit switches off the load. The timer runs down from the last movement detected and will stay on as long as there is movement across the zones of detection. In other words Auto ON: Auto OFF
Absense detector
Absence detectors are operated by a switch as normal but when the person leaves the room they turn off the load after a pre determined timed period. Upon returning the switch must be operated to reactivate the load. In other words Manual ON Auto off
At Elkay we prefer to use prescence detection because it can easily be turned into an absence detector in the diagram below.
In order to make this similar to an absence detector then use the live and switch live wires going to the original or existing switch and make them both switch lives as shown in the diagram. It is easy to repurpose the switch lines.
As you can see when someone switches the switch on or off this does not interrupt the supply to the PIR sensor. The sensor can carry on doing its job whether the switch is on or off. For energy conscious staff who already turn off their lights they will see no change and require no re-educating of how the light works. For those who leave a room with the load still on then the unit will turn off after the pre selected time period set on the sensor.
The mains powered direct controls
Although we are illustrating the mains powered direct controls here, Elkay also offer DALI control via easyDALI with both presence and absence detection combined in the same detector.
For more information call Elkay Technical
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Contact us today, and we can guarantee you get the appropriate partners and part numbers. This ensures the installation of compliant and safe Elmex connectors or Elkay's time switches and sensors.
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Danny GladdishGeneral Manager – Elkay & Elmex |
Richard BarnesSpecification and Distribution Manager |
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Karl GrantSpecification and Distribution Manager |
Francesca GrahamOrders |
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Steve AndersonTechnical Manager |