Industrial Sensors and Proximity Detection

Sensor

An element that acquires a quantitative physical property and converts it to an electrical signal.

Transducer / Sensing Element

The active element within a sensor.

Switches vs. Gauges

Switches provide electronic control signals; gauges are mechanical measuring devices.

Underlying Principles of Sensors

Sensors and transducers are always based on applications of physics or chemistry.

Range (Static Characteristic)

The minimum to maximum allowable value that can be measured by a sensor.

Span

The difference between the max and min values

Accuracy (Static Characteristic)

The difference between true and actual measured value, commonly expressed as a percentage of full-scale.

Sensitivity (Static Characteristic)

The minimum magnitude of input signal required to produce a specified output signal.

Resolution (Static Characteristic)

The smallest change in input value that produces an observable change in the output.

Hysteresis (Static Characteristic)

Maximum output difference for the same input based on whether the input was increasing or decreasing.

Repeatability (Dynamic Characteristic)

Error in output value for repeated application of the same input value (precision).

Rise Time (Dynamic Characteristic)

Time for the output to change from 10% to 90% of the final steady-state value.

Time Constant (Dynamic Characteristic)

Time it takes the output to reach 63.2% of the final output value.

Settling Time (Dynamic Characteristic)

Time it takes the output to reach within a certain percentage of the final steady-state value.

Industrial Detection Sensor

A specialized device used in automated systems to detect absence, presence, or distance of an object.

Mechanical Limit Switch

Converts mechanical motion into electrical signals using electrical contacts and an actuating mechanism.

Inductive Proximity Sensor

Detects the presence of ferrous or nonferrous metallic materials at close range.

Capacitive Proximity Sensor

Detects both metal and non-metal objects, even through insulating materials like wood or plastic.

Magnetic Proximity / Hall-Effect Sensor

Detects the presence of a magnetic field for non-contact object detection.

Ultrasonic Proximity Sensor

Emits a high-frequency sound impulse and measures echo elapsed time to detect objects.

Photoelectric Sensor

Uses a light source and light sensor to detect the absence or presence of an object.