Sensor

In technology, a sensor or probe is a component that reacts in a typical way to a certain physical or chemical variable. This reaction is output as an electrical signal that is transmitted, evaluated and can then be displayed, transmitted or stored as a measurement result. A sensor can be used, for example, to detect dangerous gases or to measure temperatures, forces, vibrations or other variables. The sensor and the evaluation unit must be coordinated to each other so that the evaluation unit can correctly assign the signal generated by the sensor to the measured variable.

Depending on the application, the ready-configured measuring devices or measuring systems with sensor or sensors and display unit can be used, or the individual components that can be matched to each other. Pre-configured systems are available with both internal and external sensors. Among the measuring devices with an external sensor, there are some, where the sensor can only be exchanged for another of the same type. In the other devices, also suitable sensors of other types can be connected. The evaluation unit of these devices recognises the connected sensor or it can be adjusted to it.

When deciding on a particular sensor, various aspects matter. One of the most important conditions that must be met is that this sensor must be able to detect the desired measured variable at the intended location with sufficient accuracy. In addition, the sensor must be suitable in its design for the conditions prevailing at the measuring point and must be able to transmit the measured value as a signal in the desired form to the intended transducer or display unit.

Here is a short list of the most important selection criteria for the sensor:

Display units for sensors
Not always the measurement results can or should be displayed directly at the measurement location. Moreover, for other tasks, the measurement data of several sensors should be displayed and evaluated together. This requires individual components that must be coordinated with each other. In order for the sensor and the display unit to be able to communicate, it must be possible to establish a corresponding connection and the sensor must provide the output signal in the format in which it is expected by the display unit. When selecting a display unit, however, many other points must also be taken into account:

Display
- Should only values from one sensor or from several be displayed?
- How far must the display be readable?
- Are the measured values sufficient or should additional calculations and evaluations or notes also be displayed?
- Should coloured info or warning lights light up for certain states or measured values?

Inputs for the measurement signal from the sensor
- How many signal inputs are required?
- Which signal types should the display unit process?

Outputs
- How many signal outputs are needed?
- Which signal types are to be passed on via the outputs?

Operability
- Can the unit be configured by the user?
- How complex are the settings?

Power supply
- With which operating voltage can the display unit be operated?
- Should the sensor be supplied with voltage via the display unit?

Dimensions and design
- Should the display unit be installed in a control panel or housing?
- From where should the interfaces and connections be accessible?

Memory
- Is storage of measurement and calculation data intended?
- Is data to be stored on an internal memory or a removable data carrier?

Data interface
- Should the current or stored data be transferred via an interface?
- Which interface types are available?

Classification of the sensors available at PCE Instruments according to the measured variable
Sensors combined with suitable dispalays or controllers can be used for a wide variety of applications for condition and process monitoring or for automatic process control. To select a sensor, the measurand and measuring range should be determined first, followed by the other requirements. PCE Instruments offers in its product range among others: