Motion Sensor Problems

Discussion in 'C-Bus Wired Hardware' started by mormj001, Oct 25, 2011.

  1. mormj001

    mormj001

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    I am having troubles with an 'Occupancy Sensor 5751L' unit detecting movement when there is no movement. This indoor unit has actually been installed outdoors in my porch area to trigger the porch light. There are no trees, webs or anything triggering it but I have heard rumours that heat/ultraviolet light/wind etc can trigger this movement. This does seem to be the case as on windy days the unit triggers more often.

    Can someone help confirm:
    1. If I need to replace this unit with the proper outdoor Occupancy Sensor 5750WPL OR
    2. Can I adjust the settings of the indoor unit to eliminate the false triggering

    Your help will be much appreciated. I am pretty comfortable adjusting the settings in the Toolkit if need be but I just need to know what the settings should be.

    Thanks
    Michael
     
    mormj001, Oct 25, 2011
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  2. mormj001

    Newman

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    The indoor motion sensors are not sealed like the outdoor model is, so they are susceptible to the strong air pressure changes occur when it is windy. They can also get bugs inside them. The plastics of the 5751L are also not of a suitable grade for regular exposure to high levels of UV, like you find outdoors. If you're going to use the 5751L outdoors, choose your location wisely!

    Whilst the 5751L does not have a dedicated sensitivity adjustment, you can sometimes reduce the effective sensitivity sufficiently by adjusting the Time Threshold parameter on the Global tab of the Toolkit UI. By default it will be 96ms but you can try increasing this to larger values which will reduce the sensitivity.

    Give it a shot and let us know how you go.
     
    Newman, Oct 25, 2011
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  3. mormj001

    Don

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    A common source of problems with the 5751 is due to air pressure differences on either side of the mounting surface. If you have the sensor mounted under the eaves, make sure the hole that the wiring goes through is sealed, or use surface wiring and avoid a hole entirely (not so attractive though).

    I suppose silicone would be a suitable sealant. I would avoid acid cure formulations to keep corrosion problems to a minimum on nearby connectors.
     
    Don, Oct 28, 2011
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  4. mormj001

    mormj001

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    Thanks for the advice guys.
    I did some tests on increasing the threshold and it seems 7-800 was working ok but still triggering every now and then (i.e. 3-4 times an hour). I have set it to the MAX threshold and doesn't trigger anymore but requires a lot of movement (i.e. more than just walking past, you must jump around a bit) to trigger the sensor.

    I did notice a 10cm size hole in the roof lining to get the wires through which I will silicon up and report back if this helps to get the threshold down to a more manageable level. It would make sense as there would be a bit of a vaccum going on that could trigger the sensor.
     
    mormj001, Oct 31, 2011
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