Capacitive Proximity Sensors, Recap:

Some applications are difficult for photo eyes.

The example in the previous slides was a fill or no fill application. If the bottle is clear, photo eyes could be used to "burn through" the bottles when they do not contain product. The problem is, bottles are not always clear, and even when they are clear, they might have labels. Capacitive switches are a better choice for applications of this nature.

Sensitivity Adjustment:

Physical Adjustment (moving the sensor towards or away from the target) is the preferred method of adjusting sensitivity when the sensor is not in direct contact with the target. This allows materials to be moved into or out of range while leaving the sensor at the factory setting.

Capacitive switches can be mounted in contact with the target.

In high-low level fill applications on big vats, for example, it is commonplace to tap into the container and mount the switch in contact with the material inside. Turck has a series of teflon wells which provide a positive seal on the tank. The capacitive switches are mounted inside the wells.

Turning the potentiometer, of course, is the second method of sensitivity adjustment. Turning the pot in a clockwise direction increases the sensitivity of the sensor. Try to adjust it in increments of a quarter turn.