Instrumentation Systems - Essay Example

A typical digitised process control instrumentation system is as follows: 2. Sensors and Transducers: Strictly speaking, a sensor is a device that receives a signal or stimulus and responds with an electrical signal, while a transducer is a converter of one type of energy into another. In practice, however, the terms are often used interchangeably. Sensors and their associated circuits are used to measure various physical properties such as temperature, force, pressure, flow, position, light intensity, etc.

These properties act as the stimulus to the sensor, and the sensor output is conditioned and processed to provide the corresponding measurement of the physical property such as temperature, pressure, level, etc. (Kester 12) (a) Temperature Sensors: Measurement of temperature is critical in modern electronic devices, especially expensive laptop computers and other portable devices with densely packed circuits which dissipate considerable power in the form of heat. Knowledge of system temperature can also be used to control battery charging as well as prevent damage to expensive microprocessors.

Compact high power portable equipment often has fan cooling to maintain junction temperatures at proper levels. In order to conserve battery life, the fan should only operate when necessary. Accurate control of the fan requires knowledge of critical temperatures from the appropriate temperature sensor. (Kester 174) The various types of temperature sensors are: Thermocouples are small, rugged, relatively inexpensive, and operate over the widest range of all temperature sensors. They are especially useful for making measurements at extremely high temperatures (up to +2300°C) in hostile environments.

They produce only millivolts of output, however, and require precision amplification for further processing. They also require cold-junction compensation (CJC) techniques.