Motion Sensor to Actuate a Relay

[professor]

Hello,
I would like to connect a motion sensor to a relay to trigger a device. I purchased a replacement motion sensor at Lowe's (Secure Home form Heath/Zenith). This motion sensor is intended to switch incandescent lights up to 500 Watts. In the instructions it mentions not for use with florescent lights. So my concern is will the motions sensor work to actuate a relay or will the relay load just damage the sensor?
Thanks,
Paul

[Al_The_Man]

I don't see a small relay being a problem, They must have a Triac or similar device that is switching the load, and often Florescent lights are not recommended because of the ballast and nature of the load.
Al.

[vanjast]

As mentioned it sounds like a light dimmer, configured for on/off operation.
Flourescent lights/ballasts change the supply voltage and current phases - This cooks the triac protection circuit, then possibly the triac.

You can get these incandescent dimmers to work with a flourescent light, but the triac protection can be made for one specific ballast type only, and it'll only work properly in on/off mode. This is too much effort so you don't see them around.

An alternative might be a bulkier sensor unit with a traditional relay, or you can attach a traditional AC relay to the current sensor triac output - this would work with anything.

I would think the relay coil inductance is not high enough to mess with the triac protection - play around a bit.

[Linghunt]

Not to beat a dead horse,

But in general relay is good way to isolate digital signals. Protect expensive devices and add reliabilty to a design. Lots of different relays out there.
(1) Contact Amp rating,
(2) Isolation of contacts to coil voltage (Don't worry about this one, bite me in the butt the other day, over 1000V contact voltage)
(3) Coil voltage and holding voltage.
(4) and others....

Opto isolators are one of the best, design in isolation is better than troubleshooting.