These include output type, load current, leakage current, voltage drop, switching frequency and electrical protections. Since most sensors drive low load current PLCs, care must be taken to ensure load current compatibility. 2-wire DC and AC sensors are designed with a minimum load current in order to operate. If the load current is below the minimum requirement the sensor will not turn on. When calculating the cumulative voltage drop of a circuit, especially those containing 2-wire sensors, it is important to include the voltage drop across the load when it is energized.
Smaller sensors provide faster switching speeds.
Important in selecting sensors, yet not always considered, is the fact that actual switching frequency will depend on target size, distance from the sensing face, distance between targets, speed of the target and size of the switch. The distance must be enough for the switch to be able to turn off before being turned back on. For example, if the application involves the sensing of gear teeth, you must consider the gaps between the teeth, the depth of those gaps and the speed of the gear. The final electrical factor to consider in choosing a proximity sensor is electrical protections. To eliminate the potential of missing the target, its size should be at least equal to or greater than the standard target.