AC proximity sensor

[rguimond]

Having an issue with these: http://www.automationdirect.com/stat...inductivev.pdf

Using them to sense whether doors are opened or closed. Blue lead is AC hot, brown connected to input on a Zelio programmable relay.

With no object in sensing distance, I get a bleed-through of between 80 and 85 volts, which is above the threshold of the input. Thus, the input is always on.

I have a tech support opened with AD, but won't get an answer until sometime tomorrow. I was hoping someone will have a solution. I'm suspecting it'll be a series resistance...

[bernie_carlton]

Two wire devices have to have enough current to function to decide when to turn all the way on. That's the leakage current. They aren't mechanical switches or magnetic switches being moved by something external. These are active electronic circuits looking at the amount of disturbance in the field of an inductor. They need current to operate.

Assuming you REALLY want to use these it will take a bypass resistor (this will be in parallel to the input of the Zelio, not in series) to allow that "waiting to decide to turn on" function to operate.

We'll need the turn-on voltage and current of the input to help calculate the proper bypass resistor.

[OkiePC]

Depending on the off-state leakage current, interposing relays may help you. I have had to add 1 watt resistors in a similar situation, but they tended to get hot for the 15 seconds that the prox switch was in the on state. Just make sure your choice of resistor is accurately calculated and sized for the right wattage if you go that route. If you choose interposing relays (my preference) make sure the relay coil requires considerably more power that the off state leakage to prevent it from overheating or false triggering.

Probably the best thing to do would be use a prox switch with built in contacts or less off-state leakage.