How to connect proximity sensor

[angeraer]

Hello, My father and I are currently building an elevator for our windturbine. Now I would like to have sensors indicating when the lift is at the top or at the bottom so the engine that operates the lift stops. I don't want to use a PLC for this. I got my hands on a few sensors like Omron E2E-X5ME1-G (NPN NO). Most sensors have 3 cables, 24v, 0v and the Output. Now is it possible to connect the Output directly to a relais? So when the lift nears the top, the sensor sees this and a relais that operates the engine disconnects the power from the engine so the lift stops. In the documentation they say that the sensor may not be connected directly to the power supply without 'load'. But what do they mean with 'load'? Thanks, Andy.

[Crossbow]

Depending in the wiring of the sensor, you can wire it to a relay. If it's a 3 wire PNP, then the output of the sensor should go to the + coil on the relay and the - coil directly to - of power supply. If it's NPN, do the opposite, wire the sensor output to - and wire + direct to power supply. If it's a two wire sensor you'll have to read the docs. Easier way might be just to buy some cheap limit switches and use the normally open or normally closed contacts just as you would the sensors, but you probably won't need the relays depending on the rating of the limit switch contacts.

[GerryM]

The 'Load' is the relay coil that you are using.

[gravitar]

I've had varying degrees of success with triggering relays directly from a prox. Some have worked flawlessly, some combinations wouldn't work at all, and I had one machine that was in a "grey area" that usually would work, but if the conditions were right, it would not close the contacts. Luckily, it did not create a hazardous situation when the circuit didn't close. The "smaller" the relay, the better your chances of success. Don't think you are going to pull in an A-B 700P with a prox switch :) If it were up to me, the limit switch idea is a better one I think. Especially since you do not want to use a PLC.

[gravitar]

I read that again and it sounds odd to me. I've never seen a 3-wire prox that wouldn't work with the signal wire not connected to a load. You just apply the supply voltage to the power leads, and it lights up when the switch makes. Now, a 2-wire prox wouldn't be very useful without a load.. You'd either have an open circuit or a short.. :)