Three-wire sensors are used in various applications from detecting parts to locating position of the actual machine. They can come in all different technologies such as inductive, photoelectric and capacitive, just to list a few. Although the sensor technology may differ, all 3-wire sensors are wired the same.A three-wire sensor has 3 wires present. Two power wires and one load wire. The power wires will connect to a power supply and the remaining wire to some type of load. The load is a device that is being controlled by the sensor. The most common type of load would be a PLC (programmable logic controller) DC input. Other examples of a load could be a relay or machine alarm, just make sure the load rating of the sensor is not exceeded. A typical 3-wire DC sensor’s output has a rating of 100mA to 200mA.