Daylight Harvesting / PIR Control

I need some help with a small project I am working on at the moment. What I need to achieve is as follows. I have a room with 10 fluro lights. There is natural light entering the room from either end. I plan to put a light level sensor in the middle (I was thinking the 5753PEIRL Mulit Function) & I also need the function for the lights to switch off after 20mins of no movement in the room (i am not sure if I need an additional PIR or if I can utilize the 5753PEIRL). I will also be installing a Key switch for the on / off operation and a 12 Chan DSI Dimmer. There might also be a need for dimming manually at the key switch but I am not sure if this is possible due to the light level sensor taking over after the dimming sequence has been pressed?

 

Yep, you can use the 5753PEIRL to do both the light level regulation and the movement detection stuff.

All good so far.

If you just dim the light level of the room with the key switch the 5753PEIRL will take over again and put the light level back where it wants it.

To be able to manually set the level of the lights the Light Level Maintenance feature of the 5753PEIRL needs to be disabled. This is possible from a second button on your key switch. On the Light Level tab of the 5753PEIRL UI an Enable group can be specified. Put the same group in here as on a second button on your key switch. When you want to disable automatic light level regulation in the 5753PEIRL, press that button on the switch to disable it. You can then dim the lights from the other button on the key switch without the 5753PEIRL overriding you.

Or, another way...
It's been my observation that unless the room is flooded with ambient light, most people seem to want the lights on at maximum brightness once they're more than a few metres away from the windows, so you might get a better overall lighting effect by only performing Light Level Maintenance on the few tubes at the ends of the room.

If it is a very long room, and you can live without manual dimming, you might be better off dividing up your fluoros into three separate circuits and putting 2 x 5753PEIRL's in, one in the middle of each of the end clusters of lights. I can imagine that the level of light coming in from each end of the room will be quite different at different times of day. To compensate, you could have the centre 4 (or 2) lights on with simple on-off control and the banks of 3 (or 4) at either end could have their own light level regulation. You could perform Light Level Maintenance of the middle cluster by just adding a 3rd 5753PEIRL if you wanted to.

Each 5753PEIRL could be configured to turn on and off all 3 banks of lights in response to motion, and still perform the light level maintenance function on their local cluster of lights.