Photoelectric Sensors

If your target is not metal, or if your target is not suitable for capacitive switching, or if your target distance is greater than a few millimeters, or a combination thereof, you can't use a prox switch. Plants are full of applications that can be solved by using inductive or capacitive prox sensors, but for those jobs that don't meet the requirements of using proximity switches, you must turn to photo eyes. Photoelectrics offer the greatest variety of products to choose from by far. They also present the greatest challenges for sensors. We'll look at the variety of photoelectric devices to choose from, and we'll explore the pros and cons of each. First, however, there are a couple of terminologies you need to be familiar with.

Excess Gain:

Excess gain is easy to understand; it's pretty much what it sounds like. Excess gain is the amount of light directed into the receiver lens over and beyond the minimum amount of light needed to trigger an output.
Excess gain is GOOD! The more the merrier. There is a chart in the Banner book, by each sensor, that is easy to read. It gives you the excess gain rating of that sensor. High excess gain helps the sensor operate in smoky, dusty or dirty environments, as shown at left.

Effective Beam

Effective Beam is covered in the following slide.