INTRODUCTION
Sensors are crucial when it comes to controlability, reliability and last
but not least to profitability of a process.
Why are sensors so important?
Sensors provide the connection between the "real" world and the world of process
control and computers. The sensors' accuracy determines the overall accuracy and reliability of the control system. The most
sophisticated analyzer or computer system with cannot correct for faulty measurements.
Both fed-batch and continuous cultures depend heavily on good sensors and
accurate measurement for good performance.
What are the general properties of a good sensor:
- optimum measurement accuracy (not as good as possible, but as good and as
accurate as necessary)
- durability
- ease of calibration and reconditioning
- sensitivity and good resolution
- selectivity
- provision of reproducable measurements
- long term stability
- fast response (important for control)
- continuous operation
- insensitivity to electrical and other environmental interference
- low operation and maintenance cost
- acceptance by users
- meet safety requirements
Fig 1: Placement of a sensor in a control system
If the sensor and the control unit are a considerable distance apart, the
sensor should be equipped with an amplifier
Use "BACK" button to get to the MAIN MENU