Contactor chatter using motion sensor to pull in.

[steve66]

I think the motion sensor is pulling in the relay just fine. Otherwise, it wouldn't chatter.

Do you have a lot of voltage drop on this circuit (maybe a lot of lights?) Maybe when the lights come on, the voltage at the motion sensor drops so much that it stops working. Then, the lights go off, the voltage goes back up, the motion sensor pulls the relay in, and over and over.

Steve

 

[engy]

Some triac's need a "snubber" to drive non-resistive circuits.
Depends on the triac and the load. It could be the problem.

A "snubber" is basically a resistor and capacitor in series across the gozinta and the goezoutta of the triac. (Based on a triac cut-sheet I happen to have)

 

[sparkyrick]

the gozinta and the goezoutta...

I don't remember seeing that on my Masters test, but i'm gonna remember it!

As far as vontage drop, that's not an issue. When I use the by-pass switch (in parallel with the sensor), the contactor pulls in like normal.

 

[LarryFine]

. . . the gozinta and the goezoutta . . .

I don't remember seeing that on my Masters test, but i'm gonna remember it!

The gozinta's, I remember: 1 gozinta 2, 2 gozinta 4, 3 gozinta 6, 4 gozinta 8, etc.

 

[steve66]

I don't remember seeing that on my Masters test, but i'm gonna remember it!

As far as vontage drop, that's not an issue. When I use the by-pass switch (in parallel with the sensor), the contactor pulls in like normal.

Yes, but maybe the voltage drops too low for the motion sensor to work, but is still high enough to pull the relay in with the sensor bypassed.

Now that I think about it, I think there is an additional voltage drop across the motion sensor, and it is probably higher when the lights turn on. It may be that the motion sensor and relay just aren't compatible.

I would suggest measuring the voltage on the input and output of the motion sensor. But I don't know how you will get any useable reading on the output since the motion sensor is apparently cycling on and off.

Steve

 

[sparkyrick]

Just to rule out the voltage drop thought, I'm gonna wire the sensor and contactor to it's own breaker and the lights to it's own breaker. Honestly, I'm not to optimistic...I have a feeling the sensor simply won't function without a resistive load.

 

[hbiss]

Many motion detectors use a triac to control the load much like a dimmer. Like dimmers, they don't like inductive loads unless they are designed for it. I don't think that there is a problem with your relay or the amount of current it's coil draws, it HAS to be much less than the motion detector rating- it just doesn't like the waveform.

I think the proper way around this is to find a motion detector that uses a relay rather than a solid state device.

-Hal